Semiconductor donor substrates for laser-transfer printing

Abstract

A donor substrate and methods for fabricating same. The donor substrate consists of an inorganic semiconductor surface (ISS) having a controlled level of dopant atoms therein, the ISS disposed on a transparent substrate suitable for use in a direct laser-transfer printing process to print conducting patterns of semiconductors having variable electrical conductivity on a receiving substrate. The ISS may include at least one intrinsic inorganic material and one extrinsic inorganic material(s) (e.g., doped semiconductor material) formed as separate layers, or may be constructed of a single material layer comprising both the intrinsic and the extrinsic inorganic semiconductor materials. In some instances, the ISS may be a multilayered film made up of multiple layers of different undoped and / or doped inorganic semiconductor materials, and / or layers of the same inorganic semiconductor material, and / or mixed layers of doped semiconductor materials and undoped semiconductor materials.

Description

SEMICONDUCTOR DONOR SUBSTRATES FOR LASER-TRANSFER PRINTINGRELATED APPLICATIONS

[0001] This application claims the priority benefit of U.S. Provisional Application 63 / 579,324, filed 29 August 2023.FIELD OF THE INVENETION

[0002] The present invention generally relates to laser-induced material transfer processes and materials.BACKGROUND

[0003] The field of Printed Electronics (PE) is related to the ability to directly print electronic and optoelectronic devices and circuits on virtually any substrate (including non-planar substrates), thus making ordinarily printed objects - smart. PE is expected to allow the integration of electronic devices such as antennas, sensors, batteries, and signal (or information) processors with “ordinary” printing capabilities in 2D and in 3D on virtually any media (such as papers, plastics, fabrics, and more). In this respect, PE offers a simple and inexpensive alternative to advanced (but much more expensive) microelectronics fabrication technology, which is limited to planar crystalline semiconductor substrates. Applications of PE include (but are not limited to) solar energy harvesting and storing, flexible displays, radio-frequency identification (RFID), and more. Digital PE means using a digital source to print electronics and usually is exploited when small number of prototypes and / or custom-made electronic printing is required.

[0004] In order to digitally print basic electrical devices such as diodes, resistors, and transistors, PE requires the ability to print thin films of metals, insulators, and semiconductor materials. Generally speaking, metallic materials (including alloys and composites), insulators, polymers, plastics, and even bio-materials are all considered to be printable materials with established knowledge of how to print these materials. The ability to digitally printsemiconductors, particularly high quality inorganic semiconductors (such as Si, Ge, GaAs, InP, GaN, and their alloys) that are characterized by high electrical mobility (defined as the ratio between the velocity of the free charge carriers and the magnitude of an applied electric field), controllable concentration (e.g., volume density) of free carriers, and an ability to control the charge polarity of the carriers (e.g., either electrons or holes) are key factors for the realization of digital PE technology. At present, most reports concerning printable semiconductors for digital PE refer to printing (mainly by the inkjet printing technology) of organic semiconductors and metal-oxides that are characterized by a limited control of the carrier's density and typical electrical mobility in the range of 10'4- 10'2cm2 / V-s (with fewer reports about mobility up to about 0.1-1 cm2 / V-s). Also, organic semiconductors tend to degrade with time and require encapsulation. These characteristics of organic semiconductor technology, particularly the low-mobility of the free carriers, should be compared to that of inorganic semiconductors. For example, silicon (Si) is known to be one of the most advanced (inorganic) semiconductors with a mobility in the range of 500-1500 cm2 / V-s for / / -type and / / -type singlecrystalline Si respectively, and means to control and adjust the concentration of free carriers over several orders of magnitude (from 1013cm'3up to 1019cm'3and more). Yet, so far (and to our best knowledge) there are no reports concerning methods and techniques to digitally print inorganic semiconductors like silicon.SUMMARY OF THE INVENTION

[0005] Below are described various embodiments of the present invention. As will become apparent from this description, a donor substrate for a direct laser transfer process according to one embodiment of the invention includes a transparent substrate, at wavelengths of light used to irradiate the donor substrate to produce droplets of material in the direct laser transfer process, and a film including an inorganic semiconductor material containing an amount of dopant atoms acting as either electron donors (such as P, As in silicon and Si, Ge in GaAs) or electron acceptors (such as B, Al, Ga in silicon and Be in GaAs) disposed on one surface of the transparent substrate. The inorganic semiconductor material may be an extrinsic inorganic semiconductor material. And, the film may further include an intrinsic and / or extrinsic inorganic semiconductor material (for example, one of Si, Ge, GaAs, AlAs, InAs, InP, GaP, GaN, AIN, InN, CdS, PbSe, or an alloy of at least one of the foregoing). Thus, the film mayinclude one, two, or more layers of material and may be a deposited film of one of an amorphous, poly-crystalline, powder, or single-crystalline material. In general, the inorganic semiconductor material and the dopant atoms of the film may be selected for creating either a printed n-type semiconductor pattern, or a printed p-type semiconductor pattern, or a printed multi-layer semiconductor pattern (such as p-n, n-p-n, etc.), or another mixed printed semiconductor patterns on a receiving substrate from the donor substrate. The dopant atoms may be present in an amount of about 1 : 104(one dopant atom to ten thousand inorganic semiconductor material atoms / molecules) to about 1 : 109(one dopant atom to one billion inorganic semiconductor material atoms / molecules).

[0006] In a further embodiment, a donor substrate for a direct laser transfer process may be formed by depositing, to a surface region of a transparent substrate, at wavelengths of light used to irradiate the donor substrate to produce droplets of material in the direct laser transfer process, a film of at least one intrinsic inorganic semiconductor material and at least one extrinsic inorganic semiconductor material. Such deposition of at least one of the intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material may be by any of: chemical vapor deposition (CVD), LP-CVD (low pressure CVD), PECVD (plasma enhanced CVD), MO-CVD (metal organic CVD), ALD (atomic layer deposition), MBE (molecular beam epitaxy), LPD / LPE (liquid phase deposition / epitaxy), sputtering, CBD (chemical bath deposition), PVD (physical vapor deposition), spray pyrolysis, or electroplating. In various instances, the at least one intrinsic inorganic semiconductor material may be deposited together with the at least one extrinsic inorganic semiconductor material or separately from the at least one extrinsic inorganic semiconductor material. And the at least one intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material may be present in separate layers of the film.

[0007] In some cases, a metallic or a semi-metallic layer comprising a dopant material may also be deposited as part of the fabrication of the donor substrate. Such a metallic or semimetallic layer may be deposited between deposition of the at least one intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material, or the metallic or semi-metallic layer may be deposited directly on a surface of the transparent substrate. In either case, heating the metallic or semi-metallic layer causes ions to be injected into the at least one layer of the intrinsic inorganic semiconductor material.

[0008] Still a further embodiment provides a patterned inorganic semiconductor receiver surface having a variable profile of dopants, formed by direct laser-transfer printing of inorganic semiconductor material from a donor substrate that is irradiated by a laser. As noted above, the donor substrate may be a transparent substrate, at wavelengths of light used to irradiate the donor substrate to produce droplets of material in the direct laser-transfer printing, and may include a film having an inorganic semiconductor material that includes an amount of dopant atoms disposed on one surface of the transparent substrate. As a result of the direct laser-transfer printing, the patterned receiver surface may have disposed thereon any of an n- type semiconductor pattern, a -type semiconductor pattern, an intrinsic / -type semiconductor pattern, a p-n junction (a junction of opposite extrinsic inorganic semiconductor materials), a p- i-n junction (a junction of extrinsic and / or intrinsic inorganic semiconductor materials), an n-i-p junction of extrinsic and / or intrinsic inorganic semiconductor materials, a bipolar inorganic semiconductor multi-layer pattern as such n-p-n or p-n-p type (known as bipolar transistor structures). Each extrinsic inorganic semiconductor pattern may have a volume density of free carriers exceeding 1018cm'3(known as heavily doped semiconductor film) a pattern having a volume density of free carriers between 1015cm'3to 1018cm'3(known as lightly doped semiconductor film) or a pattern having a volume density of free carriers below 1015cm'3(known as an intrinsic or quasi-intrinsic semiconductor film).

[0009] These and many further embodiments of the invention are described in greater detail below.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention is illustrated by way of example, and not limitation, in the figures of the accompanying drawings, in which:

[0011] Fig. 1 illustrates a transparent donor substrate having a thin film of inorganic semiconductor surface (ISS) with controllable amount of impurity atoms (e.g., dopants) across the ISS.

[0012] Figs. 2A and 2B illustrate, in a schematic fashion, Chemical Vapor Deposition (CVD) - based systems, with Fig. 2A illustrating an example of a low-pressure CVD system and Fig. 2B illustrating an example of a plasma-enhanced CVD (PE-CVD) system.

[0013] Fig. 3 illustrates, schematically, the use of a laser beam to generate a droplet from the ISS, and the droplet crossing a gap to solidify on a receiver to form a volume pixel (voxel).

[0014] Fig. 4A is a plot showing how measured electron concentration, before and after sintering, varies with the ratio of impurity atoms-to-Si (P / Si) used to create an ISS of a donor substrates.

[0015] Fig. 4B is a plot showing corresponding measured electrical mobility of electrons, before and after sintering, for ratios of impurity atoms-to-Si (P / Si) used to create an ISS of a donor substrates.

[0016] Fig. 5 illustrates an example of a multi-layer ISS on top of a transparent donor substrate where only a segment of the ISS film is doped with impurity atoms.

[0017] Fig. 6 illustrates, schematically, how a multi-layer ISS defined by ion implantation into an intrinsic ISS, with the implanted ion profile (concentration) (e.g., either P or B in the case of SiS) being determined by the ion beam energy.

[0018] Fig. 7 illustrates an example of the laser-transfer method with the laser beam being absorbed in the ISS and generating molten (or semi-molten) semiconductor droplets containing impurity atoms.

[0019] Fig. 8 illustrates an example of a donor substrate with a thin film of a metallic coating to be used as a heater and / or a source of dopant ions to be injected into a top inorganic semiconductor film (either intrinsic or extrinsic).

[0020] Fig. 9 illustrates an example of a multi-layer donor substrate having a metallic coating with a doped dielectric, such (such as a doped glass), disposed thereunder, followed by a semiconductor film where doped ions (such as P and B) from the dielectric layer diffuse into the semiconductor film during the laser-transfer process.

[0021] Fig. 10 illustrates a sequence of steps involved in the laser-transfer process, where a first step involves local diffusion of dopant ions into a semiconductor film of a donor substrate, a second step involves local melting of the semiconductor film to create a droplet, and a third step involves detachment of the droplet from the donor substrate.

[0022] Fig. 11 is a schematic illustration of a laser induced forward transfer (LIFT) process using a pulsed laser source to generate a train of pulses that are focused on an SiS of a donor substrate to eject droplets that cross a gap and solidify on a receiver to create printed semiconductor voxels.

[0023] Fig. 12 is an optical image of LIFT-printed silicon droplets on top of a glass receiver.

[0024] Fig. 13 A is a schematic illustration of a receiving substrate having a set of four metal electrodes arranged in a Van der Pauw geometry, and a printed square pattern of doped silicon droplets at the center of the substrate.

[0025] Figure 13B illustrates partial overlap among nine printed droplets represented by circles.

[0026] Fig. 14A shows an example of LIFT printing of a p-n diode junction on top of an insulating receiver (glass in this example), where a printed / / -type semiconductor square has an overlap with a printed / / -type semiconductor square to create a junction.

[0027] Figure 14B is an optical image of an actual p-n diode junction having the arrangement illustrated in Fig. 14A, after printing and laser-sintering of both semiconductor squares.

[0028] Fig. 15 is a plot illustrating current-voltage characteristics of a LIFT-printed p-n diode.

[0029] Fig. 16 is a schematic illustration of a LIFT-printed p-i-n diode junction in which printed layers / films are made of Si.

[0030] Fig. 17 is a schematic illustration of a three-terminal, LIFT-printed n-p-n bipolar transistor in which printed layers / films are made of Si.DETAILED DESCRIPTION

[0031] In various embodiments, the present invention provides methods to digitally print inorganic semiconductors, such as silicon, on virtually any media. In one embodiment, methods for fabricating donor substrates consisting of inorganic semiconductor surfaces (ISS) and for using these donor substrates in "direct laser-transfer" printing techniques (sometime also called "laser forward transfer" printing) to print, on a receiving substrate (sometimes referred to as a “receiver”), conducting patterns of semiconductors having variable electrical conductivity similar to that of ordinary "bulk" semiconductors are provided. These digitally printed semiconductor patterns, together with metals and insulators, are the basis for the ability to print Metal-Insulator-Semiconductor (MIS) and bipolar semiconductor devices as well as integrated electronic circuits and / or optoelectronic circuits. Fig. 1 illustrates an example of a donor substrate 100. In this example, donor substrate 100 may be transparent, or nearly so, at wavelengths of light used to irradiate the substrate to produce droplets of material, as described further below. Atop donor substrate 100 is a thin film of inorganic semiconductor material with a controllable amount of impurity atoms (e.g., dopants). This film is referred to herein as an inorganic semiconductor surface (ISS) 102.

[0032] Embodiments of the invention combine various techniques to deposit thin films of inorganic semiconductor materials on top of donor substrates and to adjust and to control the level of impurity atoms in the deposited film. Similar techniques were previously used to control the amount of impurity atoms in bulk semiconductors such as single-crystalline semiconductor wafers (for example, Si, Ge, GaAs, InP, GaP, etc.). The present invention exploits these techniques to create unique and novel ISS on top of any donor substrate, which can be utilized as the analogs of ink (e.g., the material to be printed) and an ink-cartridge (e.g., the ink's carrier) during a direct laser-transfer printing process, thus allowing digital printing of electronic devices (for example, diodes, resistors, and transistors) and integrated electronic circuits.

[0033] As disclosed herein, donor substrates having an ISS disposed thereon are constructed of an optionally transparent substrate (for example, glass, sapphire, quartz, or transparent flexible substrates such as organic polymers and plastic materials) and the ISS is a thin film of an inorganic semiconductor material that is deposited on top of its surface. While various deposition techniques can be utilized for this purpose, the purity of the deposited film and theability to adjust, tune, and control the amount of intentional impurities (e.g., the "dopants") will typically govern which technique and conditions are to be used.

[0034] Without wishing to be bound by any one particular method of manufacturing, CVD (chemical vapor deposition)-based techniques, such as LP-CVD (low pressure CVD), PE-CVD (plasma enhanced CVD), MO-CVD (metal organic CVD), ALD (atomic layer deposition), inorganic semiconductor growth techniques such as MBE (molecular beam epitaxy), LPD / LPE (liquid phase deposition / epitaxy), sputtering, and any other dry deposition and growth techniques can be exploited for depositing the ISS film. In addition, wet chemical growth and synthesis methods such as CBD (chemical bath deposition), PVD (physical vapor deposition), spray pyrolysis techniques, and electroplating can also be considered as tools for the deposition of the ISS film on top of the donor substrate.

[0035] Thus, in one of its aspects, the invention provides a film of an inorganic semiconductor material, the film comprising at least one intrinsic inorganic material and an amount of at least one extrinsic inorganic material with impurities (e.g., dopants; thereby forming a doped inorganic material), the film formed on a donor substrate for a direct laser transfer technique. As used herein, the term “inorganic semiconductor material” or “inorganic semiconductor” or “inorganic material” means elemental semiconductor materials of group IV, binary (two- elements), ternary (three-elements) or multi -elements semiconductor materials of either group III-V, or group III-Nitride and / or group II- VI, or other semiconductor materials that are not oligomer or polymer chain molecules, such as polyaniline. Example of elemental inorganic semiconductors is Si and of binary inorganic semiconductors is GaAs. By “intrinsic” inorganic material (or intrinsic inorganic semiconductor material), we mean a material that is not intentionally doped, such as silicon that has not been intentionally doped with impurity atoms. An intrinsic inorganic material may contain naturally occurring dopants. By “extrinsic” inorganic material (or extrinsic inorganic semiconductor material), we mean an intentionally doped material, such as / / -type (usually doped with P) or / / -type (usually doped with B) doped silicon.

[0036] The invention also provides a donor surface when used in a direct laser transfer technique, the donor surface comprising at least one intrinsic inorganic semiconductor material and / or at least one extrinsic inorganic semiconductor material containing dopants, the donor surface thus being an inorganic semiconductor surface (ISS).

[0037] Also provided as an ISS, the ISS being in the form of a film comprising at least one doped inorganic material.

[0038] Further provided is a donor surface for use in a direct laser-transfer printing method, the donor surface comprising a surface coated on at least a region thereof with a doped inorganic semiconductor material.

[0039] Also provided is a donor surface for use in a specific direct laser-transfer printing method known as the "Laser Induced Forward Transfer" (LIFT) method, the donor surface being configured and operable for printing a conducting pattern of a semiconductor material on a receiving surface, resulting in a surface having variable electrical conductivity substantially similar to that of bulk semiconductors.

[0040] As used herein, donor surfaces and methods of the invention are adaptable and usable for printing semiconductors for forming a printed metal-insulator-semiconductor (MIS) and / or bipolar electronic devices, photovoltaics, optoelectronics, and integrated electronic circuits.

[0041] In one embodiment, the film of the invention comprises at least one intrinsic inorganic semiconductor material and one extrinsic inorganic semiconductor material(s) (e.g., doped semiconductor material(s)) formed on a surface of a substrate suitable for direct laser-transfer printing methods. The film may be constructed of a single material layer comprising both the intrinsic and the extrinsic inorganic materials or two or more individual layers (multilayer) that together form the film of the invention. Such a multilayered film may comprise multiple layers of different undoped and / or doped inorganic materials, and / or layers of the same inorganic material, and / or mixed layers of doped materials and undoped materials (the presence or absence of intentional dopants distinguishing the layers of extrinsic inorganic semiconductor material and intrinsic inorganic semiconductor material, respectively, from one another).

[0042] The intrinsic or bulk inorganic material may be selected amongst semiconductor materials such as Si, Ge, GaAs, AlAs, InAs, InP, GaP, GaN, AIN, InN, CdS, PbSe, and their alloys, as well as combinations and non-stoichiometric variants of the foregoing.

[0043] The phase of the deposited semiconductor film of the invention may be selected to be amorphous, poly-crystalline, powder, or single-crystalline material.

[0044] The dopants or impurities atoms may be selected as known in the art and may include B, Al, Ga, In, P, As, Sb, Bi, and / or Li in silicon, and Si and Be in GaAs.

[0045] As may be understood, any level of doping may be achieved. In some embodiments, the amount of impurity atoms presented in a film or an ISS of the invention ranges from about 1 : 104(one impurity atom to ten thousand of inorganic atoms / molecules) to about 1 : 109(one impurity atom to a billion of inorganic atoms / molecules).

[0046] In various embodiments of the invention, the ISS is constructed of a transparent donor substrate and a thin film (e.g., of thickness one micrometer or less) of a doped inorganic material, covering or patterning one of the donor substrate faces. A thin film of doped inorganic material in accordance with the invention may comprise regions (or layers) comprising one or more different impurity atoms selected to form either an / / -type semiconductor or a / / -type semiconductor or an z-type (intrinsic) semiconductor. The amount of impurities in each of the regions or layers may be different and may vary, inter alia, based on such factors as the type of impurities to be used, the effect to be achieved, the presence of other layer materials, and other factors. As stated, the amount of impurities may range from about 1 : 104(one impurity atom to ten thousand of semiconductor atoms) to about 1 : 109(one impurity atom to a billion of semiconductor atoms).

[0047] The invention further provides an / / -type semiconductor or a / -type semiconductor donor surface comprising an inorganic material doped with at least one impurity atom type, e.g., in some embodiments, in an amount ranging between about 1 : 104to about 1 : 109, for use in a laser-transfer printing method, such as LIFT printing.

[0048] Also provided is a laser-transfer printing apparatus comprising or making use of or adapted to receive a film or an ISS according to the invention.

[0049] The invention further provides an z-type (intrinsic) semiconductor donor surface comprising an inorganic material that is intentionally undoped or having less than L IO9(impurity atoms-to-Si ratio respectively) for use in a laser-transfer printing method, such as LIFT printing.

[0050] In some embodiments, in films and ISS of the invention the inorganic material is silicon. To achieve a / / -type ISS, the silicon film may be doped with an atom selected from B,Al, Ga, and / or In. To achieve an / / -type ISS, the silicon film may be doped with an atom selected from P, As, Sb, Bi, and / or Li.

[0051] In general, any of the growth and deposition techniques disclosed herein allow in situ introduction of impurity atoms into the inorganic material. For example, in a CVD-based process to deposit silicon on top of a donor substrate, which is based on a silane (SiHj) gas as a source for Si atoms, one can incorporate additional gases such as phosphine (PHa) and / or diborane (BaHe) to create either / / -type impurity atoms (P) or / / -type impurity atoms (B) or both, in the Si matrix, respectively.

[0052] Figs. 2A and 2B illustrate, in a schematic fashion, Chemical Vapor Deposition (CVD) - based systems, with Fig. 2A illustrating an example of a low-pressure CVD system 200 and Fig. 2B illustrating an example of a plasma-enhanced CVD (PECVD) system 210. In both systems, the gases (e.g., SiHj, PHa, BaHe) 202 are injected into the process chamber via a "gas inlet" 204 toward a donor substrate 206. Mass flow controllers (MFCs) 208 determine the impurity atoms-to-silicon ratio (for example, the P / Si and / or the B / Si ratios). However, as opposed to ordinary semiconductor fabrication processes where the impurity atoms are activated to produce free carriers (either electrons or holes), the ISS donors do not necessarily require activation. Instead, one might use a method wherein, during the laser-transfer printing process (such as LIFT), the laser pulses are absorbed in the ISS thin film (on top of the donor substrate) to create droplets of inorganic semiconductors that cross a gap between the donor substrate and the receiver (e.g., the receiving substrate), cool down, and solidify on the surface of the receiver to form a volume pixel (voxel) of a conducting inorganic semiconductor. This process may be used to activate the free carriers.

[0053] Fig. 3 illustrates, schematically, this use of a laser beam 302 to generate a droplet 304 from the ISS 102. The droplet crosses the gap 306 and solidifies on the receiver 308 to form a volume pixel (voxel) 310. The printing process of pixels (or voxels) of conducting inorganic semiconductors can be repeated to create continuous two-dimensional (2D) arrays of overlapping droplets or even three-dimensional (3D) objects such as wires, rods, etc. This printing process of the droplets may provide the necessary conditions to activate free charged carriers in the semiconductor material during the solidification on the receiver substrate.

[0054] Thus, deposition of ISS films can result in varying densities (concentrations) of impurity atoms on donor substrates, thereby allowing 3D printing of both / / -type, / -type, and p- type semiconducting films of inorganic semiconductors using direct laser-transfer printing techniques.

[0055] The invention also provides methods for forming films (e.g., ISS) which involve controlling the density (concentration) of impurity atoms in the ISS donors and, therefore, in the printed pixels of the semiconductor materials (after performing the printing process). Lasertransfer printing of conducting inorganic semiconductors requires high accuracy in controlling the density of impurity atoms. By way of example, Figs. 4A shows measurements of the concentration (volume density) of free carriers (electrons in this n-type example,) versus the relative amount of phosphorous (P) atoms in n-type silicon (Si) thin film, before and after sintering which was digitally printed by the LIFT technique. From these graphs, one concludes that a change of 10% in the phosphorous-to-silicon (P / Si) relative density of impurities (for example, from about l.OxlO'4to l. lxlO'4) gives rise to a change of about one order of magnitude in the concentration of free carriers (from 2xl017cm'3to 2xl018cm'3electrons in this example). This helps to illustrate the requirement for accurate control of the amount of intentional impurities in the process of fabricating ISS donor substrates. Fig. 4B shows the corresponding electrical mobility of the free carriers before and after sintering.

[0056] Methods of the invention that achieve accurate control of the amount of impurity atoms in the film or ISS to any level desired, e.g., from about LIO4(one impurity atom to ten thousand of inorganic atoms / molecules) to about L IO9(one impurity atom to a billion of inorganic atoms / molecules), involve any of the following: a. In situ control of the mass transfer ratio between the inorganic material to be deposited / grown and the impurity atoms (e.g., dopants). For example, in a CVD process involving deposition of Si, the mass transfer ratio of SilL and PFF (or BaHe) gases can be adjusted by controlling the flow rates of the gases introduced into the deposition chamber (e.g., using mass flow controllers such as 208 shown in Fig. 2). This provides a first level of control of the ratio of P / Si (and / or B / Si) as an example to the mass transfer ratio of impurity atoms-to-inorganic atoms / molecules.b. A second level of impurity atoms-to-inorganic atoms / molecules ratio control is achieved by using a multi-layer deposition technique where the impurity atoms are introduced into a segment (or a layer) of the entire ISS film while other segments (or layer / s) of the film do not contain impurity atoms (the "undoped" layer or layers). An example is shown in Fig. 5, where a multi-layer ISS 502 is located on top of transparent donor substrate 100 where only a segment 504 of the ISS film 502 is doped with impurity atoms and segments 506a, 506b on either side of the doped segment 504 remain undoped. Dilution of the amount of impurity atoms in the printed droplets is achieved during the formation of the droplets (see Fig. 3) where fast diffusion of the impurity atoms gives rise to averaging of the amount of impurity atoms (and a dilution according to the ratio of the thickness of the layers 504, 506a, 506b). c. Post processing of ion implantation and / or diffusion to control the amount of impurity atoms-to-inorganic atoms / molecules ratio in the deposited / grown ISS film. In this case, as illustrated in Fig. 6 (which shows, schematically, the postprocessing of ion implantation), an ISS film 602 is first deposited / grown on top of the donor substrate 100 without introducing impurity atoms. Next, using known techniques such as ion implantation and / or diffusion-based processes, one can introduce the impurity atoms 604 into the ISS film 602, either into the entire ISS films or into a portion of the films as in point (b) above. The formation of droplets during the laser-transfer printing process (see Fig. 3) is expected to average the amount of impurities across the entire droplet.

[0057] Thus, the invention further provides a method for forming a film or an ISS, the method comprising depositing to a surface region of a donor surface suitable for use in direct lasertransfer printing a film of at least one intrinsic inorganic material and at least one extrinsic inorganic material with dopants.

[0058] In some embodiments, the deposition method involves any one or more of CVD (chemical vapor deposition)-based techniques, such as LP-CVD (low pressure CVD), PE-CVD (plasma enhanced CVD), MO-CVD (metal organic CVD), ALD (atomic layer deposition), inorganic semiconductor growth techniques such as MBE (molecular beam epitaxy), LPD / LPE (liquid phase deposition / epitaxy), sputtering and other dry deposition and growth techniques;wet chemical growth methods such as CBD (chemical bath deposition), PVD (physical vapor deposition), spray pyrolysis techniques and electroplating.

[0059] In some embodiments, deposition of the inorganic material is achievable in a separate step from deposition of the doped material (extrinsic inorganic material).

[0060] In some embodiments, both the intrinsic inorganic material and the extrinsic inorganic material are deposited simultaneously.

[0061] In some embodiments, the method comprises a step of deposition of a layer of at least one inorganic material and a separate step of deposition of a metallic layer on the donor substrate, acting as a source of the dopant atoms. In some embodiments, the metallic layer is deposited directly on the surface of the donor substrate, and in other embodiments, the inorganic material (intrinsic and / or extrinsic) is deposited directly on the surface of the substrate.

[0062] The thickness of the layer may vary, depending, inter alia, on the existence of other layers, as disclosed hereinbelow. Generally speaking, the thickness of the semiconductor layer may vary from few hundred nanometers (nm) up to few microns (pm). In some embodiments, the thickness ranges from 10 nm to 2.5 pm or more

[0063] Where additional layers exist, as in multi-layer donor structures, the thickness of the semiconductor layer may range between 10 to 300 nm or more.

[0064] In some embodiments, the method comprises multiple (two or more) steps of deposition, wherein each step causes deposition of the same or different material (intrinsic and / or extrinsic inorganic film or ISS).

[0065] In some embodiments, the amount of dopant atoms in the inorganic material, which forms pixels on a receiving substrate during direct-laser-transfer printing process, is tuned and controlled by combining one, two, or three of the methods described above to allow variable electrical conductivity of the printed pattern.

[0066] The film or ISS may be formed on a surface region of any donor substrate. In some embodiments, the film or ISS is formed on top of a soft, transparent and flexible donor substrate such as high-temperature thermo-plastics and polymers. Non-limiting examplesinclude PEN (polyethylene naphthalate), PEI (polyetherimide), PAI (polyamide-imides), PES (polysulfones), PPS (polyphenyline sulfide) and others.

[0067] In some embodiments, the deposition step(s) is / are performed at a temperature that does not cause a damage to the donor substrate and its surface, e.g., polymeric donor surface. Such a temperature may be any temperature not exceeding 200-250°C. In some embodiments, the temperature is between room temperature (25-30°C) and 250°C.

[0068] In some embodiments, deposition is performed using low-temperature deposition techniques such as PECVD (and / or ICP PECVD) or LPE.

[0069] The ISS of the invention or the ISS deposited according to methods of the invention may or may not be in a crystalline (or poly-crystalline) phase. In some embodiments, the ISS may be in the amorphous phase, keeping the purity and the control of impurity atoms (e.g., the dopants) level as explained before.

[0070] Thus, flexible and soft rolls of ISS donors can be produced and integrated into the direct laser-transfer printer. Crystallization of the amorphous and / or quasi-crystalline phases and activation of the impurity atoms (dopants) may take place either during formation of the droplets at the printing stage, or during the propagation of the droplets across the gap, or during the solidification stage on the receiving substrate (see Fig. 3), or during a post-printing stage of laser-based activation / sintering (of the impurity atoms). This post-printing stage does not necessarily require high laser power and, therefore, avoids unwanted high temperature effects that might appear in ordinary laser-based sintering. As an example, the plot in Fig. 4 demonstrates additional measurements of the concentration and the mobility of the free charged carriers after laser-based activation / sintering using a low laser power (and a setup quite similar to that presented in Fig. 11, but without a donor substrate). The results show an increase of carrier mobility by about an order of magnitude without a substantial change in the concentration of the carriers.

[0071] Once the film is formed, the ISS may be used in a laser-transfer method. During the laser-transfer printing method, a pulsed laser beam generates radiation that passes through the back surface of the donor substrate and impinges the front surface of the donor substrate that is coated with the inorganic semiconductor donor film or ISS. As a result, an ejection of an inorganic semiconductor droplet of either molten or semi-molten (e.g., very soft material)occurs. The droplet crosses a gap between the surface of the donor substrate and the surface of a receiving substrate or a receiver, impinges the upper surface of the receiver, cools down and solidifies. Fig. 7 illustrates an example of the laser-transfer method with the laser beam 302 being absorbed in the ISS 102 and generating molten (or semi-molten) semiconductor droplets 304 containing impurity atoms. The droplet crosses the gap 306 and solidifies on the receiving substrate (receiver) 308. A train 702 of such droplets creates a continues pattern of the semiconductor material on receiver 308.

[0072] The printing process is designed so that any consecutive droplet from a train of droplets generated from a train of laser pulses either fully or partially overlaps the first or previous droplet, causing the colliding droplets to melt, cool down, solidify, and re-crystallize together to create a practically continuous pattern of the two or more droplets in a phase of either polycrystalline or amorphous material. This process can be repeated for as many droplets as needed to create a continuous pattern of the inorganic semiconductor material on the receiving substrate having the noted average density of impurity atoms (dopants) and minimizing the amount of defects and imperfections in the printed semiconducting medium. As noted above, further improvements in the electrical and mechanical properties of the printed patterns can be obtained by post- activation / sintering processes.

[0073] The ability to control the level of impurities in the ISS film can be used to print a variety of different semiconductor materials on a receiver substrate. Thus, the invention also provides printed patterns formed according to any printing method utilizing an ISS of the invention. These patterns may, for example, be: a. Heavily doped printed semiconductors films having a high level of either / / -type impurities or / / -type impurities. A typical concentration (volume density) of the free carriers may exceed 1018cm'3. In this case, the printed semiconductor material can be considered as a semi-metal. b. Lightly doped printed semiconductor films having mid-range of either kind of impurities ( / / -type or / -type) in the range of 1015cm'3up to 1018cm'3. In this case, the printed semiconductor material can be considered as semi-conducting.c. Intentionally undoped printed semiconductor films with impurity level less than 1015cm'3. This type of printed semiconductor material can be considered as semi-insulating.

[0074] As mentioned herein, a specific example of a printable inorganic material is silicon (Si), which allows introduction of a variety of impurities, wherein each type of impurity and the relative amount of each type of impurity endows the silicon film with a preselected property; thereby opening the door for the formation of doped and undoped semiconductor films of various properties. By switching from one type of donor film to another, or by using any other method for multi-material printing, one can create a variable profile of impurities (and / or impurities and semiconductor materials) in the printed film, such as p-n semiconductor junctions (e.g., / ?-type printed semiconductor on top of / / -type semiconductor or vice-versa), bipolar device profiles such as n-p-n and p-n-p bipolar transistors, and any other multiple profile of impurities in the printed semiconducting media. This printing process can also be used to form digitally -printed (on a given receiver) heterostructures of different semiconductor materials such as (either doped or undoped) GaAs together with AlGaAs.

[0075] According to other implementations of the present technology, the film of the doped inorganic semiconductor material may be provided in a form of a stacked or multilayered form, wherein one segment of the inorganic semiconductor material is provided either undoped on top of a surface region of a doped inorganic semiconductor material layer, or on top of a metallic layer, or a layer that comprises such a doped material. Upon thermal irradiation, e.g., by a pulsed laser beam, through the back surface of the donor substrate, a metallic layer or a heater film (composed of a material selected from either carbon nanotubes, graphene, metal films, metallic nanoparticles, or any other film that can act as a source of heat) is heated, causing an ejection of dopant ions into the inorganic semiconductor which transforms into a droplet of either molten or semi-molten material, as explained hereinabove.

[0076] As demonstrated in Fig. 8, in one implementation, the donor substrate 100 is coated with a film 802 of a metallic material, on top of which a film 804 of the inorganic semiconductor material (intrinsic or extrinsic) is provided. Upon thermal irradiation, the metallic layer 802 heats up to a temperature below its metal melting point, causing a temperature increase in the inorganic semiconductor material and ejection of metal ions frommetallic layer 802 into film 804. A molten or semi-molten droplet of the inorganic semiconductor material (e.g., during printing) now comprises an amount of the doping material.

[0077] The amount of the impurity atoms may be varied by varying one or more of the following: (1) thickness of the metallic layer; (2) type of metal used; (3) laser beam profile (any one of power level, pulse duration, repetition rate, wavelength (in tunable lasers), and beam size).

[0078] Fig. 9 illustrates a further implementation. As shown, the donor surface 100 is coated with a heat film 902, e.g., such as a metallic film as in the above-described implementation, whereby a region of the heat film is coated or layered with a doped dielectric material layer 904. Examples are phosphosilicate glass (PSG) and boronsilicate glass (BSG). A layer 804 of the inorganic semiconductor material is provided on top of the doped dielectric material. Upon thermal irradiation, the heat film 902, e.g., the metallic layer, heats up, causing temperature increase in the doped dielectric material 904 and in the inorganic semiconductor material 804 and ejection of dopant ions from the layer of the dielectric material into the semiconductor material. A molten or semi-molten droplet of the inorganic semiconductor material now comprises an amount of the doping impurities.

[0079] The amount of the dopants may be varied by varying one or more of the following: (1) thickness of the heat film, e.g., metallic layer; (2) type of heat film or type of metal used; (3) thickness of the dielectric layer used; (4) type of dielectric material used; (5) concentration of the dopant material in the dielectric layer; (6) type of dopant used; (7) laser beam profile (any one of power level, pulse duration, repetition rate, wavelength in the case of using a tunable laser and beam size).

[0080] In accordance with these embodiments of the invention, the metallic layer 902 may be of a metal having a melting point higher than that of the at least one intrinsic semiconductor material, e.g., silicon. Such metal may be for example tungsten, titanium or chromium.

[0081] The dielectric material 904 doped with either / / -type or / / -type dopants may be doped glasses such as PSG or BSG or doped nitride materials such as SiN.

[0082] The layers may be patterned to allow, in the process of printing, a continues pattern of the inorganic semiconductor material on the receiving substrate wherein the pattern is formedof a single material (w-doped or / ?-doped) or may be patterned to provide spaced-apart regions, each of a different composition and characteristics.

[0083] Thus, the invention further provides a donor surface when used in a direct laser transfer technique, the donor surface comprising at least one metallic layer disposed on a surface and at least one layer of an intrinsic inorganic semiconductor material disposed on a surface region of the at least one metallic layer, wherein the at least one metallic layer is configured to eject metal ions into the at least one layer of the intrinsic inorganic semiconductor material upon heating.

[0084] The invention further provides a donor surface when used in a direct laser transfer technique, the donor surface comprising at least one heater film disposed on a surface, at least one doped dielectric material layer disposed on a surface region of said heater film and a layer of an intrinsic inorganic semiconductor material disposed on a surface region of the at least one doped dielectric material layer, wherein the at least one heater film is configured to thermally heat the at least one doped dielectric material layer and cause ejection of dopants into the at least one layer of the intrinsic inorganic semiconductor material upon heating.

[0085] The printing process involving thermal heating of a donor such as that depicted in Fig. 9 is illustrated in Fig. 10. A donor surface having at least one heater film 902 disposed on a surface 100, at least one doped dielectric material layer 904 disposed on a surface region of said heater film 902 and a layer of an intrinsic inorganic semiconductor material 804 disposed on a surface region of the at least one doped dielectric material layer 904, is exposed to a pulsed laser beam 302. As shown in a first step (1), by varying the processing conditions discussed above (thickness of metallic layer 902, type of dielectric material 904 used, concentration of the dopant material in the dielectric layer, laser beam 302 profile (any one of power level, pulse duration, repetition rate, wavelength, and beam size), etc.), it possible to control the diffusion of dopant ions 1002 (impurities) into the intrinsic semiconductor material 804. As laser irradiation continues in step 2, the laser power may be varied (increased) to cause melting of the intrinsic semiconductor material 804, e.g., silicon for example. As depicted in step 3, a molten or semimolten droplet 1004 made of the intrinsic semiconductor material, may be generated with a size and quality that depends on the factors mentioned above, e.g., time of laser exposure and thickness of the donor layers.

[0086] The invention thus provides three methodologies for obtaining patterned surfaces: a. utilizing a donor surface in which a doped inorganic semiconductor material is formed on a donor surface by deposition of dopants into the semiconductor material; b. utilizing a donor surface in which dopants are ejected from a heated metallic layer into the intrinsic inorganic semiconductor material layer forming a doped melted or semi-melted semiconductor material; and c. utilizing a donor surface in which dopants are ejected from a heated (wherein heating is provided by means of a heat film) dopant reservoir (in the form of a doped dielectric material layer) into the intrinsic inorganic semiconductor material layer, forming a doped melted or semi-melted semiconductor droplets.

[0087] Thus, the invention further provides means to print patterns on top of receiving substrates according to methods of the invention, the patterns being one or more of:(1) / / -type semiconductor patterns;(2) / / -type semiconductor patterns;(3) z-type (intrinsic) semiconductor patterns;(4) p-n (or ri-p) junctions;(5) p-i-n (or ri-i-p) junctions;(6) bipolar “transistor-like” (n-p-n or p-n-p type) and other multiplepattern structures;(7) patterns having a volume density of free carriers exceeding 1018cm' 3.5(8) patterns having a volume density of free carriers between 1015cm'3and to 1018cm'3; and(9) patterns having a volume density of free carriers below 1015cm'3.

[0088] The dopants or impurities atoms may be selected as known in the art. For example, to achieve a -type ISS, a silicon film may be doped with an atom selected from B, Al, Ga, and / or In. To achieve an / / -type ISS, a silicon film may be doped with an atom selected from P, As, Sb, Bi, and / or Li.

[0089] In another aspect of the invention, there is provided a method utilizing direct lasertransfer printing (such as LIFT) for digital printing of multi-component structures, particularly, structures combining inorganic semiconductors (using ISS donors), metals (using metallic donors), and insulators (using insulating donors). For example, a family of semiconductor devices, known as MIS (metal-insulator-semiconductor) devices, can directly be printed using a combination of the above donors. Examples include diodes, capacitors, transistors, switches, modulators, and more. In addition, one can integrate the above individual devices (in 2D and in 3D) to create printed electronic (PE) circuits. Methods to produce metallic donors and insulating donors for direct laser-transfer printing are known in the art, see for example Palla- Papavlu, Alexandra et al., “Microfabrication of polystyrene microbead arrays by laser induced forward transfer,” J. App. Phys. 108(3), 033111 (2010) for insulators (LIFT printing of polystyrene array).

[0090] Also, heavily doped printed inorganic semiconductor films, as above, can be used as semi-metals (instead of metals) while undoped films of inorganic semiconductors can be used as semi-insulators (instead of insulators). The present invention extends these printing capabilities (of the individual components) to a multi-component printing of a group of electronic devices and integrated electronic (PE) circuits.

[0091] In another aspect of the invention doped / undoped ISS might comprise light emitting semiconductor films such as GaAs, GaN and alloys made from similar groups of semiconductors (such as group III-V and group IILV-N semiconductor alloys). The invention further provides means to print light emitting patterns and / or devices having doping profiles similar to those described before (e.g., p-n. p-i-t n-p-n, p-n-p, etc.).

[0092] Example I: Silicon-based Donor Substrates for LIFT

[0093] A specific type of donor substrates containing ISS films for "direct laser transfer" printing is the case of a donor substrate having a silicon surface (SiS) and is used for LIFT printing. In this case, the SiS is deposited on one side of a glass / quartz substrate and a variableamount of dopant atoms was included in the Si S for use in a LIFT process to print single droplets of silicon and continuous patterns (in 2D) of conducting silicon. These patterns were used for measuring the electrical characteristics of the printed conducting silicon (see, e.g., Fig. 4).

[0094] Phosphorous (P) impurity atoms creating n-type dopants in silicon can be introduced into the Si S by the first technique (see Fig. 2) in-situ control of the mass transfer ratio (as discussed above) using PFF gas, diluted in H2 to about 1 : 104(e.g., 0.01% of PFF in H2 gas). The ratio of phosphorous to silicon atoms (P / Si) can be monitored by adjusting the flow rate of the PH3 and the SiFL gases using mass flow controllers that introduce the gases into a PECVD system. Boron atoms, acting as p-type dopants in silicon, can be introduced into the SiS by one of the alternative approaches described above, by first depositing a thin film of undoped silicon on top of a donor substrate, followed by boron (B) ion implantation (using a commercially available ion implanter). For example the ion energy can be chosen to be 11 keV and the dose according to the requested B / Si atoms ratio.

[0095] In a typical LIFT printing process, schematically illustrated in Fig. 11, a donor substrate 1102 with SiS 1104 facing toward a receiving substrate (receiver) 1106 is subject to pulses of laser radiation 1108 (e.g., produced by a pulsed laser 1112, various focusing optics 1114, mirrors 1116, and other optical elements, such as lens L) that pass through the transparent donor substrate 1102 and impinge the SiS 1104 to eject droplets 1110 containing the deposited doped silicon material. Printing is accomplished after the ejected droplet crosses the gap 1118 between the donor and the receiving substrate, cooling down and solidifies on the receiving substrate to create a single pixel (or voxel) 1120 of a printed doped silicon.

[0096] A continuous pattern 1122 of conducting doped silicon pixels / voxels is created by repeating the printing process of doped silicon pixels, keeping partial overlap among printed pixels to allow electrical current to flow from one conducting pixel to its neighbor and the formation of a printed conducting pattern in 2D and in 3D. An optical image of single silicon droplets, printed by LIFT, is shown in Fig. 12.

[0097] 2D arrays of partially overlapping doped silicon droplets have been printed on top of a special receiving substrate containing 4 (four) square metal (Cr / Al) electrodes in a Van der Pauw geometry. The receiving substrate 1302 with the metal electrodes 1304 is schematicallyshown in Fig. 13A, where the square 1306 at the center of the receiving substrate represents the printed Si pattern. The plot of Fig. 13B schematically shows the partial overlap of 9 (nine) droplets (represented by circles) that form a quasi-continues square of doped silicon.

[0098] A printed square, of about 300 x 300 pm2in area, has been used in this example for measuring the concentration (volume density) of free carriers (electrons for / / -type dopants (P) and holes for / / -type dopants (B)) using a Hall effect measuring setup, which allows measurement of the concentration of the carriers and their electrical mobility. As mentioned above, Fig. 4A shows the measured concentration of electrons versus the relative concentration of the impurity atoms (P / Si for electrons). The measured concentrations are in the range of 1013cm'3up to 1018cm'3. This is the range of semi-conducting silicon that is routinely utilized to fabricate semiconductor electrical devices such as diodes, resistors and transistors. Fig. 4A also shows the electron concentration for higher concentration of impurity atoms, up to 10'2(e.g., 1% of P atoms in silicon in this example). To achieve this level of impurity concentrations we used a much larger mass transfer ratio (about lOOx larger). In this case, we were able to demonstrate a printing of semi-metallic silicon having volume density in the range of 1018cm'3up to about IO20cm'3. Fig. 4B shows the corresponding electrical mobility of the free carriers prior to and after activation / sintering.

[0099] This specific example demonstrates another aspect of the invention in controlling the level of impurity atoms in Si S donor substrates and using these donors to digitally print semiconducting as well as semi-metallic silicon patterns.

[0100] Example II: LIFT Printing of a rectifying diode and a photovoltaic (PV) solar cell

[0101] Another aspect of the invention is the ability to print two-terminal electronic devices on virtually any substrate. A specific example includes printing of a p-n rectifying diode junction that is composed of a first printed film of a p-type semiconductor (using p-type ISS donor) followed by a second printed film of n-type semiconductor (a reverse order of printing can also be applied here). The two semiconductor films can be printed either one on top of the other or side by side (with an overlap).

[0102] Fig. 14A presents a specific example of creating a silicon-based p-n junction 1402 on top of insulating substrate (glass in this example) 1404 using a LIFT printer. The / -type film 1406 was printed first, followed by side printing an / / -type square 1408 having an overlap withthe / / -type pattern to create a p-n junction 1402. Fig. 14B shows a LIFT printed p-n diode junction after printing and laser-sintering of both semiconductor squares. Fig. 15 shows the current-voltage characteristics of the diode, demonstrating a rectification behavior that is typical to a diode junction (e.g., the junction conducts a current for a positive voltage while it does not allow a current flow across the junction for a negative polarity of the applied voltage).

[0103] A second example of a two-terminal electronic device 1602, which contains three printed films of semiconductors, is the p-i-n diode junction schematically illustrated in Fig. 16, which acts as a photovoltaic (PV) solar cell. In this case the structure is composed of (1) a bottom / / -type semiconductor ( / / -type Si in this example) 1604 printed on an insulating substrate 1610 (e.g., glass or plastic); (2) an intermediate printed film of semi-insulating semiconductor (Si having no intentionally doped impurity atoms in this example) 1606, and (3) a / / -type semiconductor film (p-type Si in this example) 1608. The entire printed structure 1602 creates a p-i-n diode that acts as a printed PV solar cell. Under dark conditions (e.g., no light) the diode does not support a current flow due to the insulating characteristics of the semiinsulating semiconductor film 1606. Under illumination, light is absorbed in the printed semiinsulating film 1606 to create pairs of electrons and holes that are swept toward the electrodes 1612a, 1612b, to generate a photo-current. Overall, the device converts optical energy (e.g., the absorbed light) into electrical energy (the generated electric current).

[0104] Example III: LIFT Printing of three terminal bipolar transistor

[0105] In another embodiment of the invention a three-terminal electronic device 1702 is printed on top of insulating substrate 1704 to create a transistor action. In the specific example shown in Fig. 17 the first printed film 1706 is made of / / -type semiconductor ( / / -type Si in this example), the second printed film 1708 is / -type semiconductor ( / / -type Si in this example), and the top (third) printed film 1710 is again / / -type semiconductor ( / / -type Si in this example). Ohmic contacts 1712 (usually made of metals or semi-metallic semiconductors) to each one of the films are defined to create a three-terminal structure of a bipolar transistor. In a n-p-n bipolar transistor, the intermediate / / -type film acts as the base of the transistor and the bottom and the top n-type semiconductor films act as emitter and collector respectively.

[0106] The transistor is a basic building block of integrated electronic circuits in general and particularly in printed electronics (PE). In a bipolar transistor, the base acts as a gate thatcontrols, switches, and / or modulates the current flow between the emitter and the collector of the transistor. As an example, for sufficient positive-voltage on the -type base, a current flow from the emitter to the collector is allowed while for sufficient negative-voltage on the base the current flow (from the emitter to the collector) is blocked. This is an example for a digital operation (on / off) of the printed n-p-n bipolar transistor. Similar action of a transistor can be achieved with the complementary device of a p-n-p bipolar transistor.

[0107] EMBODIMENTS

[0108] 1. A donor substrate for a direct laser transfer process, the donor substrate comprising a transparent substrate, said transparency being at wavelengths of light used to irradiate the donor substrate to produce droplets of material in the direct laser transfer process, and a film of an inorganic semiconductor material containing an amount of dopant atoms disposed on one surface of the transparent substrate.

[0109] 2 The donor substrate of embodiment 1, wherein the inorganic semiconductor material is an extrinsic inorganic semiconductor material.

[0110] 3. The donor substrate of embodiment 2, wherein the film further includes an intrinsic inorganic semiconductor material.

[0111] 4. The donor substrate of embodiment 1, wherein the inorganic semiconductor film is one of elemental semiconductor materials of group IV (such as Si and Ge), binary (two- elements) semiconductor materials of either group III-V, or group III-Nitride or group II- VI (such as GaAs, InP, GaN, CdS, ZnSe), ternary (three-elements) and multi-elements semiconductor materials of either group III-V, or group III-Nitride or group II- VI, or an alloy of at least one of the foregoing.

[0112] 5. The donor substrate of embodiment 1, wherein the film is a deposited film of one of an amorphous, poly-crystalline, powder, or single-crystalline material.

[0113] 6. The donor substrate of embodiment 1, wherein the dopant atoms are impurity atoms acting as either electron donors (such as P, As in silicon and Si, Ge in GaAs) or electron acceptors (such as B, Al, Ga in silicon and Be in GaAs).

[0114] 7 The donor substrate of embodiment 1, wherein the inorganic semiconductor material and the dopant atoms of the film are for creating a printed n-type semiconductor pattern on a receiving substrate from the donor substrate.

[0115] 8. The donor substrate of embodiment 1, wherein the inorganic semiconductor material and the dopant atoms of the film are for creating a printed p-type semiconductor pattern on a receiving substrate from the donor substrate.

[0116] 9. The donor substrate of embodiment 1, wherein the inorganic semiconductor material and the dopant atoms of the film are for creating a printed / -type (intrinsic) semiconductor pattern on a receiving substrate from the donor substrate.

[0117] 10. The donor substrate of embodiment 1, wherein the film comprises two or more material layers.

[0118] 11. The donor substrate of embodiment 1, wherein the dopant atoms are present in an amount of about 1 : 104(one dopant atom to ten thousand inorganic semiconductor material atoms / molecules) to about 1 : 109(one dopant atom to one billion inorganic semiconductor material atoms / molecules).

[0119] 12. A method for forming a donor substrate for a direct laser transfer process, the method comprising depositing to a surface region of a transparent, at wavelengths of light used to irradiate the donor substrate to produce droplets of material in the direct laser transfer process, substrate a film of at least one intrinsic inorganic semiconductor material and at least one extrinsic inorganic semiconductor material, wherein the deposition of at least one of the intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material is by any of: chemical vapor deposition (CVD), LP-CVD (low pressure CVD), PECVD (plasma enhanced CVD), MO-CVD (metal organic CVD), ALD (atomic layer deposition), MBE (molecular beam epitaxy), LPD / LPE (liquid phase deposition / epitaxy), sputtering, CBD (chemical bath deposition), PVD (physical vapor deposition), spray pyrolysis, or electroplating.

[0120] 13. The method according to embodiment 12, wherein the at least one intrinsic inorganic semiconductor material is deposited together with the at least one extrinsic inorganic semiconductor material.

[0121] 14. The method according to embodiment 12, wherein the at least one intrinsic inorganic semiconductor material is deposited separately from the at least one extrinsic inorganic semiconductor material.

[0122] 15. The method according to embodiment 12, wherein the at least one intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material are present in separate layers of the film.

[0123] 16. The method according to embodiment 12, further comprising deposition of a metallic or a semi-metallic layer comprising a dopant material.

[0124] 17. The method according to embodiment 16, wherein the metallic or semi-metallic layer is deposited between deposition of the at least one intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material.

[0125] 18. The method according to embodiment 16, wherein the metallic or semi-metallic layer is deposited directly on a surface of the transparent substrate.

[0126] 19. The method according to embodiment 16, further comprising heating the metallic or semi-metallic layer to cause ions to be injected into the at least one layer of the intrinsic inorganic semiconductor material.

[0127] 20. The method according to embodiment 12, wherein either the intrinsic inorganic semiconductor material or the extrinsic inorganic semiconductor material is silicon.

[0128] 21. A patterned receiver surface formed by direct laser-transfer printing of inorganic semiconductor material from a donor substrate that is irradiated by a laser, the donor substrate comprising a transparent, at wavelengths of light used to irradiate the donor substrate to produce droplets of material in the direct laser-transfer printing, substrate and a film including an inorganic semiconductor material that includes an amount of dopant atoms disposed on one surface of the transparent substrate, the patterned receiver surface having disposed thereon, as a result of the direct laser-transfer printing, at least one of an / / -type semiconductor pattern, a p- type semiconductor pattern, an intrinsic / -type semiconductor pattern, a p-n junction (a junction of opposite extrinsic inorganic semiconductor materials), a p-i-n junction (a junction of extrinsic and / or intrinsic inorganic semiconductor materials), an n-i-p junction of extrinsic and / or intrinsic inorganic semiconductor materials, a bipolar inorganic semiconductor multi-layer pattern as such n-p-n or p-n-p type (known as bipolar transistor structures)., a pattern having a volume density of free carriers exceeding 1018cm'3, a pattern having a volume density of free carriers between 1015cm'3and to 1018cm'3, and a pattern having a volume density of free carriers below 1015cm'3.

[0129] 22. A film of an inorganic semiconductor material, the film comprising at least one intrinsic inorganic material and / or an amount of at least one extrinsic inorganic material containing impurity atoms (dopants), the film formed on a donor substrate for a direct laser transfer technique.

[0130] 23. A donor surface, when used in a direct laser transfer technique, the donor surface comprising at least one intrinsic inorganic semiconductor material and / or at least one extrinsic inorganic material containing impurity atoms (dopants).

[0131] 24. An inorganic semiconductor surface (ISS) in a form of a film comprising at least one doped intrinsic inorganic semiconductor material.

[0132] 25. A donor surface for use in a direct laser-transfer printing method, the donor surface comprising a surface coated on at least a region thereof with a doped extrinsic inorganic semiconductor material.

[0133] 26. A donor surface for use in a Laser Induced Forward Transfer method (LIFT), the donor surface being configured and operable for printing a conducting pattern of a semiconductor material on a receiving surface, the donor surface having a variable amount of impurity atoms (dopants) substantially similar to that of bulk semiconductors.

[0134] 27. The donor surface according to any one of embodiments 23 to 26 or the film according to claim 22, being in a form of a single material layer comprising both the inorganic semiconductor material and the dopant material for creating a printed n-type semiconductor pattern on a receiving substrate.

[0135] 28. The donor surface according to any one of embodiments 23 to 27 or the film according to claim 22, being in a form of a single material layer comprising both the inorganic semiconductor material and the dopant material for creating a printed p-type semiconductor pattern on a receiving substrate.

[0136] 29. The donor surface according to any one of embodiments 23 to 28 or the film according to claim 22, being in a form of a single material layer comprising both the inorganic semiconductor material and the dopant material for creating a printed intrinsic (undoped) semiconductor pattern on a receiving substrate.

[0137] 30. The donor surface according to any one of embodiments 23 to 27 or the film according to claim 22, being in a form of a single material layer comprising both the inorganic semiconductor material and the dopant material for creating a printed semi-metallic (either n+or p+type) semiconductor pattern on a receiving substrate.

[0138] 31. The donor surface according to any one of embodiments 23 to 27 or the film according to claim 21, being in a form of a single material layer comprising both the inorganic semiconductor material and the dopant material or in the form of a multilayer comprising two or more material layers.

[0139] 32. The donor surface according to any one of embodiments 23 to 31 or the film according to claim 1, wherein the intrinsic / extrinsic inorganic semiconductor material is selected from one of claim 4.

[0140] 33. The donor surface or film according to embodiments 27 to 30, wherein the intrinsic / extrinsic inorganic semiconductor material is silicon.

[0141] 34. The donor surface or film according to embodiment 32, being patterned with one or more type of impurity atoms.

[0142] 35. The donor surface according to any one of embodiments 23 to 34 or the film according to claim 22, wherein the intrinsic inorganic semiconductor material and / or the extrinsic inorganic semiconductor material being of a phase selected from amorphous, polycrystalline, powder and single-crystalline material.

[0143] 36. The donor surface according to any one of embodiments 23 to 35 or the film according to claim 22, wherein the impurity atoms or material doping being selected according to claim 6.

[0144] 37. The donor surface according to any one of embodiments 23 to 35 or the film according to claim 22, wherein the amount of impurity atoms present in the extrinsic inorganicsemiconductor material ranges from about 1 : 104(one impurity atom to ten thousand of inorganic atoms / molecules) to about 1 : 109(one impurity atom to a billion of inorganic atoms / molecules).

[0145] 38. The donor surface according to any one of embodiments 23 to 37 or the film according to claim 22, constructed of a transparent donor substrate and a film of the intrinsic inorganic semiconductor material and / or the extrinsic inorganic semiconductor material, patterning one or more regions of the donor substrate.

[0146] 39. The donor surface or film according to embodiments 38, wherein the one or more regions are continuous or spaced apart regions.

[0147] 40. The donor surface or film according to embodiments 37, wherein each of the spaced apart regions differ in at least one of type of impurity atoms and type of inorganic semiconductor material (either intrinsic or extrinsic).

[0148] 41. The donor surface or film according to embodiment 38, wherein at least one of the regions is an w-type semiconductor or a -type semiconductor or intrinsic (undoped) semiconductor and at least another of said regions is a -type semiconductor or an / / -type semiconductor or intrinsic (undoped) semiconductor.

[0149] 42. An / / -type or a / / -type or intrinsic-type semiconductor donor surface comprising an inorganic material doped with at least one impurity atom type in an amount ranging between about 1 : 104and about 1 : 109, for use in a laser-transfer printing method.

[0150] 43. An w+-type or a ?+-type semi-metallic donor surface comprising an inorganic semiconductor material doped with at least one impurity atom type in an amount ranging between about 1 : 104to about 1 : 102, for use in a laser-transfer printing method.

[0151] 44. A laser-transfer printing apparatus comprising or implementing a donor surface according to any one of embodiments 23 to 43.

[0152] 45. A method for forming a film according to any one of embodiments 22 to claim 28, the method comprising depositing to a surface region of a donor surface suitable for use in direct laser-transfer printing at least one intrinsic inorganic semiconductor material and / or at least one extrinsic inorganic semiconductor material.

[0153] 46. The method according to embodiment 45, wherein deposition comprises any one or more of chemical vapor deposition (CVD).

[0154] 47. The method according to embodiment 46, wherein CVD is one or more of LP-CVD (low pressure CVD), PECVD (plasma enhanced CVD), MO-CVD (metal organic CVD), and ALD (atomic layer deposition).

[0155] 48. The method according to embodiment 45, wherein deposition comprises MBE (molecular beam epitaxy), LPD / LPE (liquid phase deposition / epitaxy) or sputtering.

[0156] 49. The method according to embodiment 45, wherein deposition comprises CBD (chemical bath deposition), PVD (physical vapor deposition), spray pyrolysis and electroplating.

[0157] 50. The method according to embodiment 45, wherein the at least one intrinsic inorganic semiconductor material is deposited together with the at least one extrinsic inorganic semiconductor material (doped material).

[0158] 51. The method according to embodiment 45, wherein the at least one intrinsic inorganic semiconductor material is deposited separately from the at least one extrinsic inorganic semiconductor material.

[0159] 52. The method according to embodiment 45, wherein the at least one intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material (doped material) are present in separate layers.

[0160] 53. The method according to embodiment 45, comprising a step of deposition of a layer of the at least one intrinsic inorganic semiconductor material and a step of deposition of a metallic layer, being as a source of dopant atoms comprising a doped material of a layer at least one extrinsic inorganic semiconductor material, or a semi-metallic layer being a source of dopant atoms that diffuse into intrinsic and / or extrinsic inorganic semiconductor materials.

[0161] 54. The method according to embodiment 53, wherein the metallic layer is deposited directly on the surface of the substrate.

[0162] 55. The method according to any one of embodiments 45 to 54, wherein either the intrinsic inorganic semiconductor material or the extrinsic inorganic semiconductor material is silicon.

[0163] 56. The method according to any one of embodiments 45 to 55, wherein the donor substrate is a soft, transparent and / or flexible material, or glass.

[0164] 57. The method according to any one of embodiments 45 to 55, wherein the donor substrate is a high-temperature thermo-plastic or polymer.

[0165] 58. The method according to embodiment 57, wherein the high-temperature thermoplastic or polymer is selected from PEN (polyethylene naphthalate), PEI (polyetherimide), PAI (polyamide-imides), PES (polysulfones) and PPS (polyphenyline sulfide).

[0166] 59. A donor surface, when used in a direct laser transfer technique, the donor surface comprising at least one metallic layer disposed on a surface and at least one layer of an intrinsic / extrinsic inorganic semiconductor material disposed on a surface region of the at least one metallic layer, wherein the at least one metallic layer is configured to eject metal ions into the at least one layer of the intrinsic / extrinsic inorganic semiconductor material upon heating.

[0167] 60. A donor surface, when used in a direct laser transfer technique, the donor surface comprising at least one film heater disposed on a surface, at least one doped dielectric material layer disposed on a surface region of said film heater and a layer of an intrinsic inorganic semiconductor material disposed on a surface region of the at least one doped dielectric material layer, wherein the at least one film heater is configured to thermally heat the at least one doped dielectric material layer and cause ejection of dopants into the at least one layer of the intrinsic inorganic semiconductor material upon heating.

[0168] 61. A patterned receiver surface formed according to any one of embodiments 45 to 58, the pattern being selected from an w-type semiconductor patterns, a -type semiconductor patterns, an intrinsic / -type semiconductor pattern, a p-n junction (a junction of opposite extrinsic inorganic semiconductor materials), a p-i-n or n-i-p junction (a junction of extrinsic and / or intrinsic inorganic semiconductor materials), a bipolar inorganic semiconductor multilayer pattern as such n-p-n or p-n-p type (known as bipolar transistor structures).,, a pattern having a volume density of free carriers exceeding 1018cm'3, a pattern having a volume densityof free carriers between 1015cm'3and to 1018cm'3and a pattern having a volume density of free carriers below 1015cm'3.

[0169] 62. A patterned receiver surface formed according to any one of embodiments 45 to 58, having two, three, or more metallic or semi-metallic patterns of terminals to the extrinsic semiconductor patterns and / or films.

[0170] 63. A patterned receiver surface formed according to any one of embodiments 61 to 62, adaptable and usable for forming a printed metal-insulator-semiconductor (MIS) electronic device and integrated electronic circuits.

[0171] 64. A patterned receiver surface formed according to any one of embodiments 61 to 62, adaptable and usable for forming a printed photovoltaic (PV) solar cell, the pattern being selected from a p-ri (or ri-p) junction or a p-i-n (or a ri-i-p) junction of extrinsic and / or intrinsic inorganic semiconductor materials.

[0172] 65. A patterned receiver surface formed according to any one of embodiments 61 to 62, adaptable and usable for forming a printed bipolar transistor, the pattern being selected from a n-p-n or a p-n-p structure of extrinsic and / or intrinsic inorganic semiconductor materials.

[0173] Thus, semiconductor donor substrates for laser-transfer printing processes have been described.

Claims

CLAIMS:What is claimed is:

1. A donor substrate for a direct laser transfer process, the donor substrate comprising a transparent, at wavelengths of light used to irradiate the donor substrate to produce droplets of material in the direct laser transfer process, substrate and a film of an inorganic semiconductor material containing an amount of dopant atoms disposed on one surface of the transparent substrate.

2. The donor substrate of claim 1, wherein the inorganic semiconductor material is an extrinsic inorganic semiconductor material.

3. The donor substrate of claim 2, wherein the film further includes an intrinsic inorganic semiconductor material.

4. The donor substrate of claim 1, wherein the inorganic semiconductor film is one of elemental semiconductor materials of group IV, binary (two-elements) semiconductor materials of either group III-V, or group III-Nitride or group II- VI, ternary and multi-elements semiconductor materials of either group III-V or group III-Nitride or group II- VI, or an alloy of at least one of the foregoing.

5. The donor substrate of claim 1, wherein the film is a deposited film of one of an amorphous, poly-crystalline, powder, or single-crystalline material.

6. The donor substrate of claim 1, wherein the dopant atoms are impurity atoms acting as either electron donors or electron acceptors.

7. The donor substrate of claim 1, wherein the inorganic semiconductor material and the dopant atoms of the film are for creating one of: a printed n-type semiconductor pattern on a receiving substrate from the donor substrate, a printed p-type semiconductor pattern on a receiving substrate from the donor substrate, or a printed / -type (intrinsic) semiconductor pattern on a receiving substrate from the donor substrate.

8. The donor substrate of claim 1, wherein the film comprises two or more material layers.

9. The donor substrate of claim 1, wherein the dopant atoms are present in an amount of about 1 : 104(one dopant atom to ten thousand inorganic semiconductor material atoms / molecules) to about 1 : 109(one dopant atom to one billion inorganic semiconductor material atoms / molecules).

10. A method for forming a donor substrate for a direct laser transfer process, the method comprising depositing to a surface region of a transparent, at wavelengths of light used to irradiate the donor substrate to produce droplets of material in the direct laser transfer process, substrate a film of at least one intrinsic inorganic semiconductor material and at least one extrinsic inorganic semiconductor material, wherein the deposition of at least one of the intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material is by any of: chemical vapor deposition (CVD), LP-CVD (low pressure CVD), PECVD (plasma enhanced CVD), MO-CVD (metal organic CVD), ALD (atomic layer deposition), MBE (molecular beam epitaxy), LPD / LPE (liquid phase deposition / epitaxy), sputtering, CBD (chemical bath deposition), PVD (physical vapor deposition), spray pyrolysis, or electroplating.

11. The method according to claim 10, wherein the at least one intrinsic inorganic semiconductor material is deposited according to one of: together with the at least one extrinsic inorganic semiconductor material, or separately from the at least one extrinsic inorganic semiconductor material.

12. The method according to claim 10, wherein the at least one intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material are present in separate layers of the film.

13. The method according to claim 10, further comprising deposition of a metallic or a semimetallic layer comprising a dopant material.

14. The method according to claim 13, wherein the metallic or semi-metallic layer is deposited between deposition of the at least one intrinsic inorganic semiconductor material and the at least one extrinsic inorganic semiconductor material, or is deposited directly on a surface of the transparent substrate.

15. The method according to claim 14, further comprising heating the metallic or semi-metallic layer to cause ions to be injected into the at least one layer of the intrinsic inorganic semiconductor material.

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