Array interconnected CsPbCl3 ultraviolet photodetector and preparation method thereof

Abstract

The present invention belongs to the field of micro-nano manufacturing and optoelectronic devices, and specifically discloses an array-interconnected CsPbCl3 ultraviolet photodetector and a preparation method thereof, comprising the steps of: S1 preparing a cross-type electrode array on a substrate; S2 using a photolithography overlay process to transfer a CsCl precursor mask pattern, and using a thin film deposition process to deposit a CsCl precursor pattern on a substrate, the CsCl precursor pattern being located in the cross-type electrode array and connected thereto; S3 using a thin film deposition process to deposit a precursor PbCl2 layer on the CsCl precursor pattern, annealing to diffuse and crystallize the CsPbCl3 perovskite, and obtaining a patterned CsPbCl3 perovskite film. The present invention overcomes the problem of incompatibility between the traditional solution method and the photolithography process, can reduce the pixel size, increase the pixel density, and reduce the electrode area ratio, improve the imaging device array density, and realize the miniaturization and integration of the detector.

Description

Technical Field

[0001] The present invention belongs to the field of micro-nano manufacturing and optoelectronic devices, and more specifically, relates to an array-interconnected CsPbCl3 ultraviolet photodetector and a preparation method thereof. Background Art

[0002] Image sensors have detection bands ranging from ultraviolet light, visible light to infrared light. They are an important branch of sensor technology devices, an indispensable peripheral for computer multimedia, and a core device in the Internet and intelligent control. Among them, ultraviolet photodetectors and ultraviolet image sensors have become a hot spot for research and development in countries around the world due to their great application value in military fields such as missile approach warning and ultraviolet imaging guidance, as well as in civilian fields such as corona monitoring and fire detection. However, today's ultraviolet photodetectors have problems such as large device size, high power consumption, poor band selectivity, and low response rate. For example, vacuum ultraviolet detectors require ultraviolet filters to work, while solid-state ultraviolet detectors require refrigeration devices to work. For this reason, the development of ultraviolet photodetectors based on new wide-bandgap optoelectronic materials has received widespread attention.

[0003] In recent years, perovskite materials represented by CsPbCl3 have gradually attracted attention and applications in the field of ultraviolet photodetection and ultraviolet image sensing due to their suitable photon bandgap and excellent optoelectronic properties. A large number of reports have been published on ultraviolet photodetectors based on wide-bandgap perovskite films, which have shown good performance and broad application prospects. However, there are few reports on ultraviolet image sensing array devices based on patterned wide-bandgap perovskite films. The devices prepared by some rare research institutes either focus on the preparation of the film itself, or the photosensitive layer film is not patterned, resulting in serious optical crosstalk problems, and the electrode array is not interconnected, and the pixel density is generally low, making it difficult to truly realize the ultraviolet imaging function.

[0004] The main reason for this phenomenon is that the solubility of wide-bandgap perovskite films such as CsPbCl3 film precursor CsCl in common solvents is too low, which limits the solution method preparation of high-quality films; perovskite films are easily soluble in solvents such as acetone, which will inevitably make the perovskite film preparation process incompatible with current microelectronics processes; film preparation and its patterning have become a dual problem for the preparation of miniaturized, integrated array-interconnected CsPbCl3-based perovskite ultraviolet photodetectors. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides an array-interconnected CsPbCl3 ultraviolet photodetector and a preparation method thereof, the purpose of which is to prepare a miniaturized and integrated array-interconnected CsPbCl3-based perovskite ultraviolet photodetector and achieve good ultraviolet imaging function.

[0006] To achieve the above object, according to one aspect of the present invention, a method for preparing an array-interconnected CsPbCl3 ultraviolet photodetector is proposed, comprising the following steps:

[0007] S1, preparing a cross-shaped electrode array on a substrate;

[0008] S2, using a photolithography process to transfer a CsCl precursor mask pattern, and using a thin film deposition process to deposit a CsCl precursor pattern on a substrate according to the CsCl precursor mask pattern, wherein the CsCl precursor pattern is located in a cross-type electrode array and connected thereto;

[0009] S3. A PbCl2 layer is deposited on the CsCl precursor pattern by a thin film deposition process, and then annealed to diffuse and crystallize the CsPbCl3 perovskite to obtain a patterned CsPbCl3 perovskite film, thereby completing the preparation of an array-interconnected CsPbCl3 ultraviolet photodetector.

[0010] As a further preferred embodiment, step S1 prepares a cross-type electrode array on a substrate, which specifically includes the following steps: using a photolithography process to transfer the metal electrode array and the dielectric layer mask pattern, and using a coating process to deposit a horizontal metal electrode, a dielectric film, and a vertical metal electrode on the substrate in sequence according to the metal electrode array and the dielectric layer mask pattern, wherein the horizontal metal electrode and the vertical metal electrode are vertically cross-distributed, and the dielectric film is located at the intersection of the horizontal metal electrode and the vertical metal electrode.

[0011] As a further preferred embodiment, the metal electrode array has m rows and n columns, wherein m and n are both integers between 25 and 500, and in the metal electrode array, the spacing between a pair of matched transverse electrodes and longitudinal electrode units is between 3 μm and 5 μm,

[0012] As a further preference, the thickness of the transverse metal electrode and the longitudinal metal electrode are both 30 nm to 50 nm.

[0013] As further preferred, the material of the dielectric film is Al2O3, SiO2, HfO2 or Si3N4, and its thickness is 10nm to 30nm.

[0014] As a further preferred embodiment, after the cross-shaped electrode array is prepared, it is subjected to recrystallization annealing, and the recrystallization annealing temperature is 0.4 to 0.7 times the melting point of the electrode metal material.

[0015] As a further preference, the electrode material is gold, the annealing temperature is 200° C. to 320° C., the time is 15 min to 30 min, and the heating rate is 10° C. / min to 15° C. / min.

[0016] As further preferred, the thickness of the CsCl precursor pattern and the precursor PbCl2 layer are both 100 nm to 200 nm, and the thickness ratio of the precursor PbCl2 layer to the CsCl precursor pattern layer is 165:200.

[0017] As further preferred, the thin film deposition process is dual-source co-evaporation or single-source continuous evaporation.

[0018] According to another aspect of the present invention, there is provided an array-interconnected CsPbCl3 ultraviolet photodetector, which is prepared by the above-mentioned preparation method.

[0019] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0020] 1. The present invention presents a patterned array distribution by combining photolithography overlay and perovskite film deposition process, and covers the surface of the cross-shaped metal electrode array, and realizes electrical connection by overlapping the perovskite part of the patterned array distribution. Finally, the detector uses the excellent selectivity of the perovskite photosensitive layer in the ultraviolet band and the unique metal electrode interconnection structure. Specifically, by improving the CsPbCl3 perovskite film prepared by the two-step process, combining the photolithography overlay process, the coating process and the stripping process, the CsPbCl3 ultraviolet detector array is prepared, and the effective preparation of the array-interconnected CsPbCl3 ultraviolet detector is realized, and the perovskite gas-phase assisted preparation process is combined with the photolithography process, so that the device pixel size is reduced and the pixel density is increased, and the photosensitive film patterning solves the optical crosstalk problem. At the same time, this method overcomes the problems of complex preparation process of the traditional solution method, difficulty in large-area preparation, and incompatibility with the traditional photolithography process. In addition, the present invention reduces the electrode area ratio, improves the array density of the imaging device, reduces the number of external electrode pins, improves the device's integration and data transmission efficiency, and realizes the miniaturization and integration of the detector by designing and preparing a cross-type metal electrode array structure.

[0021] 2. The CsPbCl3 perovskite thin film array in the present invention is prepared by an improved two-step process, that is, firstly, a CsCl precursor pattern is deposited in the electrode unit gap of the horizontal electrode array and the vertical metal electrode array by a photolithography overlay process combined with a perovskite thin film preparation process, and then a precursor PbCl2 layer is deposited on the entire surface by a vapor deposition process such as resistive thermal evaporation. The two precursor layers have a certain thickness ratio relationship so that the molar ratio in the film finally formed satisfies the stoichiometric ratio, and annealing is performed to diffuse and crystallize the CsPbCl3 perovskite to obtain a CsPbCl3 perovskite thin film array. The improved two-step perovskite thin film preparation process in the present invention solves the problems of complex solution method preparation process of CsPbCl3 perovskite thin film, poor process repeatability, and difficulty in preparing large-area thin film arrays.

[0022] 3. The cross-type array interconnected metal electrode array of the present invention is prepared by photolithography, coating and stripping processes, and its shape distribution can be pre-defined by the photolithography process. The horizontal metal electrodes and the vertical metal electrodes are vertically cross-distributed. At the same time, a dielectric film insulating partition is set at the intersection of the horizontal metal electrodes and the vertical metal electrodes to avoid mutual influence of the electrodes. The electrode structure designed in the present invention can reduce the electrode area and improve the array density, so as to realize the miniaturization and integration of the detector and realize high-resolution imaging of ultraviolet detection.

[0023] 4. In the present invention, the spacing between the transverse electrode and the longitudinal electrode units is between 3 and 5 μm. If the spacing is too small, it will be difficult to remove the glue during electrode preparation, resulting in a short circuit between the electrodes. At the same time, compared with other materials, the carrier transmission distance of CsPbCl3 perovskite material is less than 100 nm. Therefore, if the electrode transmission spacing is too large, the carrier recombination during transmission will be serious and the external photoelectric response will be weak.

[0024] 5. The thickness of the metal electrode of the present invention is between 30 and 50 nm. If the thickness of the electrode is too small, it is easy to break during the degumming process; if the thickness of the electrode is too large, the photoresist will be denatured due to the high temperature during the electrode preparation process, and it cannot be removed, affecting the preparation of subsequent electrodes or perovskite films; and the horizontal and vertical electrodes present a vertical stacking structure. If the bottom electrode is too thick, the top electrode will be bridged, which will change the contact barrier between the electrode and the perovskite film and affect the current response characteristics. In addition, the thickness of the dielectric layer is between 10 and 30 nm. If the thickness is too small, the insulation is too weak, the tunneling voltage is small, and the bias voltage that can be applied to the device is limited; if the thickness is too large, the high temperature during the film formation process will denature the photoresist and it cannot be removed cleanly, affecting the preparation of subsequent electrodes and perovskite films; and the insulating layer is located in the center of the vertical stacking structure of the electrode. If the thickness is too thick, it will also cause the above-mentioned bridging problem.

[0025] 6. After preparing the cross-type electrode array, the present invention performs recrystallization annealing on it. This is because a photolithography process (including a complete set of photolithography, coating, and degumming) is required later. During this process, the electrode will easily fall off. After recrystallization, the adhesion to the substrate is enhanced, thereby improving the stability of the detector.

[0026] 7. The array interconnected metal electrodes in the present invention are made of gold, and the recrystallization annealing temperature, time and heating rate are optimized. Specifically, when the temperature is too low to reach the recrystallization temperature of gold, and when the temperature is too high, the gold electrode film will be isolated; if the annealing time is too short, the recrystallization will be incomplete; if the annealing time is too long, the surface characteristics of the silicon wafer will be changed, affecting the adhesion of the subsequent perovskite film; if the heating rate is too high, the quality of the recrystallized film will deteriorate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of an array-interconnected CsPbCl3 ultraviolet photodetector provided in an embodiment of the present invention;

[0028] Figure 2 yes Figure 1 Cross-sectional view (front view) of the CsPbCl3 UV photodetector device with interconnections in the array.

[0029] In all the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 11 - substrate, 12 - lateral metal electrode, 13 - dielectric film, 14 - vertical metal electrode, 15 - CsPbCl3 thin film UV-sensitive layer. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] An embodiment of the present invention provides an array of interconnected CsPbCl3 ultraviolet photodetectors, such as Figure 1 and Figure 2As shown, it includes a substrate 11, a cross-type electrode array and a CsPbCl3 thin film ultraviolet photosensitive layer 15, wherein the cross-type electrode array is arranged on the substrate, and includes a vertically cross-distributed transverse metal electrode 12 and a longitudinal metal electrode 14, and it is m rows and n columns (i.e., m rows of transverse metal electrodes, n columns of longitudinal metal electrodes), wherein m and n are integers between 25 and 500, and the spacing between a matching pair of transverse metal electrodes and longitudinal metal electrode units is between 3 and 5 μm; the cross-region of the transverse electrode and the longitudinal electrode is insulated and separated by a dielectric film 13; the CsPbCl3 thin film ultraviolet photosensitive layer includes a plurality of photosensitive units, each of which is located between the cross-type electrode array, and the two ends of the photosensitive unit are respectively connected to the transverse metal electrode and the longitudinal metal electrode.

[0032] The method for preparing the above-mentioned array interconnected CsPbCl3 ultraviolet photodetector comprises the following steps:

[0033] S1. Use photolithography to transfer the metal array electrode and the dielectric layer mask pattern. Combined with the coating process and wet stripping process, deposit the horizontal metal electrode, dielectric film, and vertical metal electrode on the substrate in sequence to complete the preparation of the cross-type electrode array.

[0034] Specifically, the substrate material can be a rigid substrate such as a silicon wafer, a quartz wafer, a sapphire wafer, or a flexible substrate such as PET, PI, and the substrate thickness is preferably between 20 and 50 nm; the coating process is magnetron sputtering, electron beam evaporation, atomic layer deposition or resistive thermal evaporation, etc.; the metal electrode material is Ti, Ni, Cr, Au, Ag, etc.

[0035] S2. Placing the cross-shaped electrode array prepared above in an annealing furnace to recrystallize the electrode film. The recrystallization annealing temperature is 0.4 to 0.7 times the melting point of the electrode metal material.

[0036] S3. The CsCl precursor mask pattern transfer is completed by using a photolithography overlay process, and a patterned CsCl precursor film is prepared by combining a perovskite film deposition process and a wet stripping process. The pattern is contacted and interconnected with the cross-type electrode by partially overlapping.

[0037] Specifically, the shape, size, and position distribution of the CsCl precursor layer pattern prepared by the photolithography overlay process can be modified by adjusting the photolithography mask pattern; the perovskite thin film deposition process is a dual-source co-evaporation process or a single-source continuous evaporation process.

[0038] S4. Cover the precursor PbCl2 layer with a perovskite film deposition process, and diffuse and crystallize the CsPbCl3 perovskite through annealing to form a patterned CsPbCl3 perovskite film.

[0039] S5. Wire bonding and packaging the above samples.

[0040] The CsPbCl3 perovskite film preparation method in the present invention overcomes the problems of complex preparation process of traditional solution method, difficulty in large-area preparation, and incompatibility with traditional photolithography process, and innovatively proposes a two-step preparation process of CsPbCl3 perovskite film combined with photolithography, which can greatly reduce the pixel size and improve the pixel density compared with the traditional metal mask method or laser etching method, and at the same time overcomes the problem of optical crosstalk in array-interconnected perovskite photodetectors; the device structure in the present invention introduces a cross-type electrode array, which reduces the electrode area ratio, improves the array density of the imaging device, reduces the number of external electrode pins, and improves the device's integration and data transmission efficiency.

[0041] The following are specific embodiments:

[0042] Example 1

[0043] (1) 10 nm Cr and 20 nm Au were deposited in sequence by photolithography, electron beam evaporation, and resistive thermal evaporation, and then wet stripping was used to prepare lateral metal electrodes.

[0044] (2) Using photolithography combined with magnetron sputtering to deposit 30 nm Al2O3 on the surface of the cross section of the horizontal and vertical metal electrodes;

[0045] (3) Using photolithography, electron beam evaporation, and resistive thermal evaporation to deposit 10 nm Cr and 40 nm Au in sequence, combined with a wet stripping process, a vertical metal electrode was prepared. The horizontal and vertical electrodes formed a cross-type interconnected electrode array with a gap of 3 μm;

[0046] (4) placing the cross-interconnected electrode array in an annealing furnace for recrystallization annealing, heating from room temperature to 200°C at a rate of 15°C / min, and maintaining for 30 min;

[0047] (5) using photolithography overlay process and resistive thermal evaporation process to deposit 165nm CsCl, combined with wet stripping process, to prepare a patterned CsCl precursor layer;

[0048] (6) 200 nm PbCl2 was deposited by resistive thermal evaporation process, and annealed at 240°C for 30 min to form a CsPbCl3 crystal film in the patterned CsCl area, thereby preparing a patterned CsPbCl3 perovskite UV photodetector array;

[0049] (7) Encapsulating and wiring the prepared CsPbCl3 ultraviolet photodetector array.

[0050] Example 2

[0051] (1) 10 nm Cr and 20 nm Au were deposited in sequence by photolithography, electron beam evaporation, and resistive thermal evaporation, and then wet stripping was used to prepare lateral metal electrodes.

[0052] (2) Using photolithography combined with magnetron sputtering to deposit 30 nm Al2O3 on the surface of the cross section of the horizontal and vertical metal electrodes;

[0053] (3) Using photolithography, electron beam evaporation, and resistive thermal evaporation to deposit 10 nm Cr and 40 nm Au in sequence, combined with a wet stripping process, a vertical metal electrode was prepared. The horizontal and vertical electrodes formed a cross-type interconnected electrode array with a gap of 5 μm;

[0054] (4) placing the cross-interconnected electrode array in an annealing furnace for recrystallization annealing, heating from room temperature to 250°C at a rate of 10°C / min, and maintaining for 25 min;

[0055] (5) using photolithography overlay process and resistive thermal evaporation process to deposit 165nm CsCl, combined with wet stripping process, to prepare a patterned CsCl precursor layer;

[0056] (6) Depositing 200 nm PbCl2 by solution spin coating process, annealing at 240°C for 30 min, forming a CsPbCl3 crystal film in the patterned CsCl area, thereby preparing a patterned CsPbCl3 ultraviolet photodetector array;

[0057] (7) Encapsulating and wiring the prepared CsPbCl3 ultraviolet photodetector array.

[0058] Example 3

[0059] (1) 10 nm Cr and 20 nm Au were deposited in sequence by photolithography, electron beam evaporation, and resistive thermal evaporation, and then wet stripping was used to prepare lateral metal electrodes.

[0060] (2) Using photolithography combined with magnetron sputtering to deposit 10 nm Al2O3 on the surface of the cross section of the horizontal and vertical metal electrodes;

[0061] (3) Using photolithography, electron beam evaporation, and resistive thermal evaporation to deposit 10 nm Cr and 40 nm Au in sequence, combined with a wet stripping process, a vertical metal electrode was prepared. The horizontal and vertical electrodes formed a cross-type interconnected electrode array with a gap of 3 μm;

[0062] (4) placing the cross-interconnected electrode array in an annealing furnace for recrystallization annealing, heating from room temperature to 320°C at a rate of 15°C / min, and maintaining for 10 min;

[0063] (5) using photolithography overlay process and resistive thermal evaporation process to deposit 165nm CsCl, combined with wet stripping process, to prepare a patterned CsCl precursor layer;

[0064] (6) 200 nm PbCl2 was deposited by resistive thermal evaporation process, and annealed at 240°C for 30 min to form a CsPbCl3 crystal film in the patterned CsCl area, thereby preparing a patterned CsPbCl3 ultraviolet photodetector array;

[0065] (7) Encapsulating and wiring the prepared CsPbCl3 ultraviolet photodetector array.

[0066] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an array interconnected CsPbCl3 ultraviolet photodetector, characterized in that: The steps include: S1. Prepare a cross-shaped electrode array on a substrate; specifically, the steps include: using a photolithography process to transfer the metal electrode array and the dielectric layer mask pattern, and using a coating process to sequentially deposit a lateral metal electrode, a dielectric film, and a longitudinal metal electrode on the substrate according to the metal electrode array and the dielectric layer mask pattern, wherein the lateral metal electrode and the longitudinal metal electrode are vertically cross-distributed, and the dielectric film is located at the intersection of the lateral metal electrode and the longitudinal metal electrode; S2, using a photolithography process to transfer a CsCl precursor mask pattern, and using a thin film deposition process to deposit a CsCl precursor pattern on a substrate according to the CsCl precursor mask pattern, wherein the CsCl precursor pattern is located in a cross-type electrode array and connected thereto; S3, depositing a precursor PbCl2 layer on the CsCl precursor pattern by a thin film deposition process, and then annealing to diffuse and crystallize the CsPbCl3 perovskite to obtain a patterned CsPbCl3 perovskite film, thereby completing the preparation of an array-interconnected CsPbCl3 ultraviolet photodetector; The thin film deposition process is dual-source co-evaporation or single-source continuous evaporation.

2. The method for preparing an array interconnected CsPbCl3 ultraviolet photodetector according to claim 1, characterized in that: The metal electrode array has m rows and n columns, wherein m and n are both integers between 25 and 500. In the metal electrode array, the spacing between a pair of matching transverse electrodes and longitudinal electrode units is between 3 μm and 5 μm.

3. The method for preparing the array interconnected CsPbCl3 ultraviolet photodetector according to claim 1, characterized in that: The thickness of the transverse metal electrode and the longitudinal metal electrode are both 30nm to 50nm.

4. The method for preparing an array interconnected CsPbCl3 ultraviolet photodetector according to claim 1, characterized in that: The material of the dielectric film is Al2O3, SiO2, HfO2 or Si3N4, and the thickness thereof is 10nm-30nm.

5. The method for preparing an array interconnected CsPbCl3 ultraviolet photodetector according to claim 1, characterized in that: After the cross-shaped electrode array is prepared, it is subjected to recrystallization annealing, and the recrystallization annealing temperature is 0.4 to 0.7 times the melting point of the electrode metal material.

6. The method for preparing an array interconnected CsPbCl3 ultraviolet photodetector according to claim 5, characterized in that: The electrode material is gold, the annealing temperature is 200°C to 320°C, the time is 15min to 30min, and the heating rate is 10°C / min to 15°C / min.

7. The method for preparing an array interconnected CsPbCl3 ultraviolet photodetector according to claim 1, characterized in that: The thickness of the CsCl precursor pattern and the precursor PbCl2 layer are both 100nm to 200nm, and the thickness ratio of the precursor PbCl2 layer to the CsCl precursor pattern layer is 165:

200.

8. An array interconnected CsPbCl3 ultraviolet photodetector, characterized in that: The method is described in any one of claims 1 to 7.

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