Method for doping two-dimensional semiconductor and application

Abstract

The invention discloses a method for doping a two-dimensional semiconductor and application. The method specifically comprises the following steps: preparing a patterned viscous polymer layer; adhering the pattern side of the patterned viscous polymer layer to another viscous polymer with a flat surface to form a patterned through hole; doping agents are dropped into the patterned through holes, and the doping agents flow along the patterned through holes; after the dopant is solidified, tearing off the patterned viscous polymer layer on the surface to form a patterned dopant with a viscous polymer; and transferring the patterned dopant with the viscous polymer to a two-dimensional semiconductor for doping. According to the method, the doping region, the doping concentration and the doping polarity can be accurately controlled, and then a logic circuit can be constructed.

Description

Technical Field

[0001] The present invention belongs to the field of electronic devices, and more specifically, mainly relates to a method for doping two-dimensional semiconductors and applications thereof. Technical Background

[0002] With the development of semiconductor technology, two-dimensional semiconductors have been widely used in electronic devices, optoelectronic devices, sensors and other fields due to their rich material types, controllable layer thickness, and excellent electrical and optical properties. Especially in ultra-thin, flexible electronic devices and low-power optoelectronic devices, it is believed that they are expected to continue or even break the limitations of Moore's Law. However, the practical application of two-dimensional semiconductors in these applications depends critically on the ability to precisely control their electrical properties through doping. In the field of two-dimensional semiconductors, doping faces important challenges because two-dimensional semiconductors are only a single atomic layer or a few atomic layers thick, making it difficult to dope using traditional ion implantation technology. Current doping methods for two-dimensional semiconductors have limitations in controlling the doping area, doping concentration, and doping polarity, which hinders the realization of precise and controllable doping.

[0003] In order to solve the doping problem of two-dimensional semiconductors, it is very important to develop a new doping method with simple process and controllable doping area, doping concentration and doping polarity. Summary of the invention

[0004] In order to avoid the deficiencies of the above-mentioned prior art, the present invention provides a method for doping two-dimensional semiconductors and its application, which can accurately control the doping area, doping concentration and doping polarity, and thus construct a logic circuit.

[0005] The present invention solves the technical problem by adopting the following technical solution:

[0006] A method for doping a two-dimensional semiconductor:

[0007] Step 1): preparing a patterned adhesive polymer layer;

[0008] Step 2): attaching the pattern side of the patterned adhesive polymer layer to another piece of adhesive polymer with a flat surface to form a patterned through hole;

[0009] Step 3): dripping a dopant into the patterned through hole, and the dopant flows along the patterned through hole;

[0010] Step 4): after the dopant solidifies, tear off the patterned sticky polymer layer on the surface to form a patterned dopant with a sticky polymer;

[0011] Step 5): transferring the patterned dopant with the sticky polymer to the two-dimensional semiconductor for doping.

[0012] Furthermore, the method of preparing the patterned viscous polymer layer includes: using standard photolithography technology to photolithograph patterns on a substrate, casting a viscous polymer onto the photolithographed substrate, and forming a patterned viscous polymer layer after curing.

[0013] Furthermore, there are a plurality of patterned through holes, and the plurality of patterned through holes are not interconnected.

[0014] Further, the transferring includes peeling off the adhesive polymer.

[0015] Furthermore, the adhesive polymer is polydimethylsiloxane (PDMS) or polypropylene carbonate (PPC) or a PDMS / PPC double-layer structure.

[0016] Application of the method for doping two-dimensional semiconductors in electronic devices.

[0017] In summary, compared with the prior art solutions, the above technical solutions provided by the present invention can achieve the following beneficial effects:

[0018] (1) The present invention provides a method for doping a two-dimensional semiconductor, which can use a viscous polymer template to prepare a patterned dopant layer, and the pattern of the dopant layer has a high degree of customization, and dopant layers of different shapes and sizes can be prepared.

[0019] (2) When preparing patterned dopants, the present invention can change the charge transfer between the dopant and the two-dimensional material by changing different doping materials and proportions, thereby showing different performances.

[0020] (3) The method for doping a two-dimensional semiconductor provided by the present invention can achieve regional doping by setting a plurality of non-connected through holes, and has low requirements on equipment and simple process. Therefore, it can be applied to building logic circuits, giving it a broad application prospect in the field of electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic flow chart of a method for doping a two-dimensional semiconductor in Embodiment 1 of the present invention;

[0022] Figure 2 A schematic diagram of the structure of a transfer-doped transistor in Example 2 of the present invention;

[0023] Figure 3 A transfer characteristic curve of a transistor subjected to transfer doping in Example 3 of the present invention;

[0024] Figure 4 A schematic diagram of the inverter circuit and a schematic diagram of the structure in Embodiment 4 of the present invention;

[0025] Figure 5 A functional relationship diagram between the input voltage and output voltage of the inverter in Example 4 of the present invention. DETAILED DESCRIPTION

[0026] In order to more clearly illustrate the purpose and advantages of the present invention, the following embodiments are combined with the accompanying drawings to further describe the present invention in detail. The specific embodiments described below are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Example 1

[0028] This embodiment uses Magic Blue (MB) dopant as an example to prepare a patterned dopant. The process of this method for doping a two-dimensional semiconductor can be found in Figure 1 The specific preparation method of Example 1 is as follows:

[0029] Step 1): preparing a patterned adhesive polymer layer;

[0030] Step 1.1) Photolithography of the trench pattern on the substrate using standard photolithography techniques:

[0031] Spin the photoresist onto the glass substrate at a speed of 5000 rpm on a spin coater, place it on a hot plate at 105°C after 30 seconds of spin coating, and perform photolithography after heating for 5 minutes. Weigh 2g of NaOH on a balance, pour it into a glass container, add 500ml of water, stir it thoroughly to make a developer, put the photolithographic glass substrate into the developer and let it stand for 25 seconds, and a photolithographic pattern is formed on the glass substrate.

[0032] Step 1.2) The viscous polymer is molded onto the photolithographic substrate, and after curing, a channel patterned viscous polymer layer is formed:

[0033] In the embodiment, the viscous polymer takes PDMS as an example. 20g of PDMS main agent is weighed in a beaker using a balance, and then 1g of curing agent is added thereto. A magnetic particle is added to the beaker, and the main agent and curing agent are fully mixed at room temperature for 30 minutes, and then allowed to stand for 30 minutes to eliminate bubbles; the PDMS after standing is poured onto a glass substrate with a photolithographic channel pattern, and is placed in an oven at 80°C, and kept warm for 4 hours to allow the PDMS to solidify. After solidification, the patterned PDMS is lifted along the edge to form a patterned PDMS layer.

[0034] Step 2): attaching the channel side of the patterned adhesive polymer layer to another piece of adhesive polymer with a flat surface to form a patterned through hole;

[0035] Step 3): dripping a dopant into the patterned through hole, and the dopant will flow along the patterned through hole;

[0036] MB was dissolved in acetonitrile solvent to form an organic dopant solution, and then the organic dopant solution was dropped on the contact edge of two PDMS sheets and allowed to stand at room temperature for 10 minutes to allow the solvent to enter the patterned through holes.

[0037] Step 4): after the dopant solidifies, tear off the patterned sticky polymer layer on the surface to form a patterned dopant with a sticky polymer;

[0038] The film was placed on a hot plate and heated at 60° C. for 2 min to evaporate excess solvent and solidify the organic dopant, and finally the upper patterned PDMS was slowly peeled off to obtain a patterned dopant with PDMS.

[0039] Step 5): Using a transfer platform, the patterned dopant with PDMS is transferred to the two-dimensional semiconductor for doping.

[0040] The transfer platform is aligned with the surface of the two-dimensional material and pressed into contact. After contact, it is heated at 100°C for 3 minutes, and then the PDMS is lifted up to complete the doping of the two-dimensional material.

[0041] Example 2

[0042] This embodiment provides a transistor preparation process using MoTe2 as a two-dimensional semiconductor. The transistor structure prepared by this method can be found in Figure 2 The specific preparation method of Example 2 is as follows:

[0043] Step 1: Prefabricate and functionalize the gold electrode;

[0044] A photolithography mask with a channel length of 30 μm was customized. After photolithography development, the SiO2 / Si substrate was placed in an evaporator to evaporate 50 nm thick gold. After evaporation, it was soaked in acetone for 10 minutes, the photoresist in the non-electrode area was washed off, and it was blown dry with nitrogen to obtain a gold electrode; the prepared gold electrode was placed in a sealed container, a small amount of ODTS was added to the bottom of the container, and the container was placed in an oven at 80°C for 4 hours to keep the electrode in the ODTS gas atmosphere for functionalization.

[0045] Step 2: Stripping the gold electrode;

[0046] Spin-coat 80 g / L PMMA on the surface of the functionalized gold electrode at a speed of 4000 rpm for 40 seconds and then place it on a constant temperature hot plate for heating at 150°C for 5 minutes to completely cover the gold electrode with PMMA. Then use PDMS to peel off the functionalized electrode from the substrate and adhere it to the PDMS surface in preparation for the transfer in step 4.

[0047] Step 3: Transferring the two-dimensional semiconductor to a substrate;

[0048] Another SiO2 / Si substrate was cleaned with ultrapure water, acetone, and isopropanol in an ultrasonic cleaner for 5 minutes each, dried with nitrogen, and irradiated in a UV ozone machine for 15 minutes. The layered MoTe2 was transferred to the SiO2 / Si substrate by mechanical exfoliation;

[0049] Step 4: Transferring the gold electrode to the two-dimensional semiconductor;

[0050] Use a transfer platform to transfer the gold electrode peeled off by PDMS in step 2 to the MoTe2 surface, heat at 120°C for 2 minutes, and then peel off the PDMS. Then spin-coat the chloroform solution on the surface of the MoTe2 device at a speed of 2000 rpm for 30 seconds to remove the residual polymer PMMA on the surface.

[0051] Step 5: Doping the two-dimensional semiconductor.

[0052] The method of Example 1 is used to dope the channel of the MoTe2 device to form a transistor.

[0053] Example 3

[0054] This example provides a method for testing and processing the electrical performance of the two-dimensional material transistor after transfer doping obtained in Example 2. The instruments are a semiconductor parameter meter and a probe station, and the processing software is Origin. The specific steps are as follows:

[0055] Step 1: In a glove box filled with argon, fix the transistor in the center of the probe station and insert the probes on the source, drain and gate electrodes. Use a Keysight 2912A precision digital source meter to apply gate voltage and source-drain voltage to the transistor, with the drain electrode grounded;

[0056] Step 2: When testing the transfer characteristics, the source-drain voltage is a constant voltage of -1V, the gate voltage is scanned from -60V to 60V, and the step is 2V;

[0057] Step 3: Use Origin to process the data. The transfer characteristic curve of the transistor is shown in the attached figure. Figure 3 As shown in Figure 2, the original MoTe2 exhibits typical bipolar characteristics. When MB is transferred to the channel, the performance changes from bipolar characteristics to unipolar P-type, and the threshold voltage moves toward the positive gate voltage, indicating typical P-type doping behavior.

[0058] Example 4

[0059] This example provides a method for constructing an inverter using transistors that control the doping polarity of different regions. The transistor structure and circuit diagram prepared by this method can be found in Figure 4 , the specific steps are as follows:

[0060] Step 1: Dissolve MB and N-DMBI in acetonitrile and chlorobenzene solvents to form organic dopant solutions, then drop the two organic dopants into different through-holes formed by two PDMS sheets, and let stand at room temperature for 10 minutes to allow the solvent to enter the patterned through-holes. Then place it on a hot plate and heat it at 60°C for 2 minutes to evaporate the excess solvent. Finally, slowly peel off the upper patterned PDMS to obtain a patterned MB and N-DMBI dopant film with PDMS.

[0061] Step 2: Transfer the electrode prepared in Example 2 to the mechanically exfoliated MoTe2 surface, and then spin-coat the chloroform solution on the surface of the MoTe2 device at a speed of 2000 rpm for 30 seconds to remove PMMA;

[0062] Step 3: Use a transfer platform to transfer the patterned MB and N-DMBI dopant films to the MoTe2 device channel.

[0063] Step 4: Follow Figure 4 The circuit in the figure is connected with a probe, and a constant voltage is applied by the Keysight 2912A precision digital source meter. When a negative input voltage is applied, the P-FET is turned on and the device produces a large output voltage; conversely, when a positive input voltage is applied, the N-FET is turned on and the output voltage is zero, thereby realizing the function of the inverter and showing the voltage transfer characteristics of the uniform complementary inverter circuit under different power supply voltages. The results are shown in Figure 5 .

[0064] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. A person skilled in the art of the present invention may also make several simple deductions, modifications or substitutions based on the concept of the present invention. These deductions, modifications or substitutions also fall within the scope of the claims of the present invention.

Claims

1. A method for doping a two-dimensional semiconductor, characterized in that: Step 1): preparing a patterned adhesive polymer layer; Step 2): attaching the pattern side of the patterned adhesive polymer layer to another piece of adhesive polymer with a flat surface to form a patterned through hole; Step 3): dripping a dopant into the patterned through hole, and the dopant flows along the patterned through hole; Step 4): after the dopant solidifies, tear off the patterned sticky polymer layer on the surface to form a patterned dopant with a sticky polymer; Step 5): transferring the patterned dopant with the sticky polymer to the two-dimensional semiconductor for doping.

2. The method for doping a two-dimensional semiconductor according to claim 1, characterized in that: The method for preparing the patterned viscous polymer layer is as follows: using standard photolithography technology to photolithograph patterns on a substrate, casting a viscous polymer on the photolithographed substrate, and after curing, forming a patterned viscous polymer layer.

3. A method for doping a two-dimensional semiconductor according to any one of claims 1-2, characterized in that: There are a plurality of patterned through holes, and the plurality of patterned through holes are not interconnected.

4. A method for doping a two-dimensional semiconductor according to any one of claims 1 to 3, characterized in that: The transferring includes peeling off the adhesive polymer.

5. A method for doping a two-dimensional semiconductor according to any one of claims 1 to 4, characterized in that: The adhesive polymer is polydimethylsiloxane (PDMS) or polypropylene carbonate (PPC) or a PDMS / PPC double-layer structure.

6. Application of the method for doping a two-dimensional semiconductor as described in claims 1-5 in electronic devices.

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