Preparation Method and Application of Low-Dimensional AlN Material on MoS2

Abstract

The present invention discloses a preparation method and application of low-dimensional AlN materials on MoS2, which are applied in the field of photodetectors. By chemical vapor deposition, two-dimensional MoS2 material layers with different thicknesses are prepared on a silica layer. In electron beam evaporation, Al layers with different thicknesses are prepared. Using plasma chemical vapor deposition, low-dimensional AlN material layers with different thicknesses are grown. The two-dimensional MoS2 material layer and the low-dimensional AlN material layer form a high Schottky barrier and an internal built-in electric field. The present invention realizes the growth of low-dimensional AlN on two-dimensional MoS2, constructs a junction-type heterojunction, and exhibits a self-powered effect, a very high deep ultraviolet light responsivity, and a fast response ability.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly relates to a method for preparing low-dimensional AlN material on MoS2 and its application. Background Art

[0002] In recent years, low-dimensional materials have been proven to have great potential in the application of new-generation optoelectronic devices. Due to the unique physical and chemical properties of low-dimensional materials at the nanoscale, they have become a hot research topic in the scientific research community and the industrial community. AlN material has a direct bandgap of 6.2 eV, and has good physical and chemical stability, high electron mobility and high thermal conductivity, and is one of the preferred materials for preparing deep ultraviolet detectors. At present, the application of AlN bulk materials in photodetectors has been proven to have good deep ultraviolet selectivity. When AlN is only a few nanometers thick, it will form a structure similar to two-dimensional graphene. Due to the photogenerated carriers being confined in the low-dimensional space, the deep ultraviolet detection performance will be more excellent.

[0003] At present, two-dimensional heterojunctions are an emerging research direction. It utilizes the photovoltaic effect between heterojunction materials to generate photocurrent without an external power supply. Molybdenum disulfide (MoS2), as the most popular two-dimensional material, has a direct bandgap of 1.6 eV and has been proven to have excellent performance in photodetection. If a MoS2-based AlN detector is successfully prepared, it will have great development prospects and is expected to be applied in extreme fields such as space communication, deep sea exploration and geological exploration in the future. Nevertheless, AlN material is very easy to grow along the c-axis orientation, has a large lattice mismatch with the substrate, and is easy to form a three-dimensional island structure. This work is considered a worldwide problem. Summary of the Invention

[0004] In order to overcome the defects in the prior art that there is no MoS2-based AlN detector and the AlN material is easy to form a three-dimensional island structure with the substrate, the present invention provides a method for preparing low-dimensional AlN material on MoS2 and its application.

[0005] The present invention realizes the growth of low-dimensional AlN material on two-dimensional MoS2, and can form a deep ultraviolet photodetector with a low-dimensional AlN / MoS 2 Schottky heterojunction. This detector can work without an external power supply, solving the problem that commercially available deep ultraviolet detectors need to be additionally installed with a complex filter system. At the same time, the whole preparation process has no complex operations and no harmful by-products are generated, providing an effective solution for the next generation of self-powered, high-performance deep ultraviolet photodetectors.

[0006] The present invention adopts the following technical solutions:

[0007] A method for preparing low-dimensional AlN material on MoS2, comprising:

[0008] After cleaning the silica layer and the silicon substrate, two-dimensional MoS2 material layers with different thicknesses are prepared by chemical vapor deposition to obtain MoS2 / SiO2 / Si;

[0009] Transfer MoS2 / SiO2 / Si to electron beam evaporation, and deposit Al layers with different thicknesses to obtain Al / MoS2 / SiO2 / Si;

[0010] Transfer Al / MoS2 / SiO2 / Si to plasma enhanced chemical vapor deposition (PECVD), introduce nitrogen and ammonia, turn on the plasma radio frequency, and realize the growth of low-dimensional AlN material layers with different thicknesses;

[0011] Prepare Ti / Au electrodes with different thicknesses;

[0012] Place the structure with the prepared Ti / Au electrodes in an annealing furnace for annealing at different temperatures, so that the metal forms ohmic contacts with the low-dimensional AlN material layer and the two-dimensional MoS2 material layer.

[0013] Furthermore, two-dimensional MoS2 material layers with different thicknesses are prepared by chemical vapor deposition to obtain Al / MoS2 / SiO2 / Si. Specifically:

[0014] Take 0.03 - 0.06 g of molybdenum oxide powder and 0.1 - 0.15 g of sulfur powder, the growth distance is 15 - 20 cm, the air pressure is maintained at atmospheric pressure, the growth time is 10 - 15 minutes, and the growth temperature is 700 - 750 °C.

[0015] Furthermore, during the growth of the AlN material layer: ammonia / nitrogen is 50 scmm / 100 sccm, the growth temperature is 800 - 900 °C, the plasma intensity is 100 - 150 W, the growth pressure is 10 - 100 kp, and the growth time is 20 - 30 minutes.

[0016] Preferably, in S1, the cleaning of the substrate includes ultrasonic cleaning with water, acetone, and ethanol in sequence for 5 - 10 minutes, and then drying with high-purity dry nitrogen.

[0017] Preferably, the growth process of MoS2 is as follows: take 0.03 - 0.06 g of molybdenum oxide powder and 0.1 - 0.15 g of sulfur powder, the growth distance is 15 - 20 cm, the air pressure is maintained at atmospheric pressure, the growth time is 10 - 15 minutes, and the growth temperature is 700 - 750 °C;

[0018] In addition, the growth temperature and plasma intensity of plasma enhanced chemical vapor deposition directly determine the quality and thickness of the AlN material layer; the growth pressure affects the growth rate of the AlN material, and thus affects the thickness of the AlN material;

[0019] Therefore, the ammonia / nitrogen is 50 scmm / 100 sccm, the growth temperature is 800 - 900 °C, the plasma intensity is 100 - 150 W, the growth pressure is 10 - 100 kp, and the growth time is 20 - 30 minutes.

[0020] Furthermore, the electrode preparation process is as follows: First, spin-coat positive photoresist for 50 - 60 s using a spin coater at a rotational speed of 4600 - 5000 rpm. After pre-baking (heat treatment at 75 - 95 °C for 4 - 5 min), expose it to deep ultraviolet light source for 15 - 20 s, develop (for 60 - 65 s), and perform reactive ion etching treatment using plasma for 3 - 5 min, dry it with hot nitrogen for 4 - 6 min. After evaporating the electrode, ultrasonically vibrate it in hot acetone for 8 - 10 minutes to remove the electrode in the photoresist area.

[0021] If the annealing temperature is too high, it is easy to cause the oxidation of MoS2, affecting the device performance. If the annealing temperature is too low, good ohmic contact cannot be achieved. Preferably, the annealing temperature is set at 550 - 600 °C.

[0022] The above preparation method is applied in a photodetector, and the obtained detector has the following structure:

[0023] It sequentially includes a silicon substrate, a silicon dioxide layer, a two-dimensional MoS2 material layer, and a low-dimensional AlN material layer from bottom to top. The two-dimensional MoS2 material layer is provided with a first metal electrode, the low-dimensional AlN material layer is provided with a second metal electrode, and the two-dimensional MoS2 material layer and the low-dimensional AlN material layer form a high Schottky barrier to form a built-in electric field.

[0024] Furthermore, the thickness of the silicon substrate is 300 - 400 μm, the crystal plane is (101), and the resistance is 0.01 - 0.1 Ω.

[0025] Furthermore, the low-dimensional AlN material layer covers three-quarters of the two-dimensional MoS2 material layer. According to actual processing needs, the coverage area can be adjusted according to the actual situation.

[0026] Furthermore, the thickness of the silicon dioxide is 150 - 200 nm.

[0027] Furthermore, the thickness of the low-dimensional AlN material layer is 5 - 15 nm.

[0028] Furthermore, the thickness of the MoS2 material layer is 1 - 5 nm.

[0029] Furthermore, both the first metal electrode and the second metal electrode are sequentially stacked Ti metal layer and Au metal layer from bottom to top; the thicknesses of the Ti metal layer and the Au metal layer are 40 - 80 nm and 80 - 110 nm respectively.

[0030] Furthermore, the thickness of the Al layer is 3 - 12 nm.

[0031] The thickness of the Al layer directly determines the thickness of the subsequent AlN layer. If the Al layer is too thick, the subsequently prepared AlN will also be very thick. If the Al layer is too thin, the AlN material will be discontinuous and not suitable for device preparation.

[0032] Furthermore, the lengths of the first metal electrode and the second metal electrode are both 140 - 170 μm, and the widths are both 110 - 130 μm; the distance between the first metal electrode and the second metal electrode is 90 - 110 μm.

[0033] Advantages of the present invention:

[0034] (1) The present invention can operate without an external power supply, and the device exhibits high deep ultraviolet detection performance, mainly due to the high Schottky barrier between AlN and MoS2, forming a strong built-in electric field.

[0035] (2) A two-dimensional heterojunction structure of low-dimensional material AlN and two-dimensional MoS2 is constructed, taking advantage of the huge specific surface area, quantum confinement effect, and high carrier mobility of two-dimensional materials. At the same time, there are no complex operations and other harmful by-products during the preparation process, providing an effective solution for the next generation of self-powered, high-performance deep ultraviolet photodetectors.

[0036] (3) The preparation method of the present invention is applied to deep ultraviolet photodetectors, and the obtained products have stable performance and can be applied to extreme fields such as space communication, deep sea exploration, and geological exploration, with considerable economic benefits. Description of the Drawings

[0037] Figure 1 is a schematic cross-sectional view of the structure obtained by the preparation method of the present invention;

[0038] Figure 2 is an OM image of the MoS2 thin film on SiO2 / Si of the present invention;

[0039] Figure 3 is a schematic diagram of the low-dimensional AlN material layer grown on the MoS2 thin film of the present invention;

[0040] Figure 4 is the I-V performance graph of the AlN / MoS2 Schottky-type deep ultraviolet photodetector under 280 nm ultraviolet light in Example 2 of the present invention;

[0041] Figure 5 is the I-T performance graph of the AlN / MoS2 Schottky-type deep ultraviolet photodetector under 280 nm ultraviolet light in Example 2 of the present invention. Detailed Embodiments

[0042] The present invention will be further described in detail below in conjunction with embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0043] Embodiment 1

[0044] A preparation method and application of low-dimensional AlN material on MoS2. The photodetector prepared by this preparation method is as Figures 1 - 3 shown, including a silicon substrate 1, a silicon dioxide layer 2, a two-dimensional MoS2 material layer 3 and a low-dimensional AlN material layer 4. The two-dimensional MoS2 material layer is provided with a first metal electrode 5, and the low-dimensional AlN material layer is provided with a second metal electrode 6. The two-dimensional MoS2 material layer and the low-dimensional AlN material layer form a high Schottky barrier to form a built-in electric field.

[0045] The preparation method includes the following steps:

[0046] Step 1: After cleaning 200nm SiO2 / (101)Si, by chemical vapor deposition (CVD), take 0.03g molybdenum oxide powder and 0.1g sulfur powder, the growth distance is 15cm, the air pressure is maintained at atmospheric pressure, the growth time is 10 minutes, and the growth temperature is 700 °C to obtain MoS2 / SiO2 / Si;

[0047] Step 2: Transfer the MoS2 / SiO2 / Si obtained in Step 1 to electron beam evaporation, and use its general process method to achieve evaporation coating of a 3nm Al layer to obtain Al / MoS2 / SiO2 / Si;

[0048] Step 3: Transfer the Al / MoS2 / SiO2 / Si in Step 2 to plasma enhanced chemical vapor deposition (PECVD), introduce ammonia / nitrogen at 50scmm / 100sccm, the growth temperature is 800 - 900 °C, the plasma intensity is 100W, the growth air pressure is 10kpa, and the growth time is 20 minutes to achieve the growth of low-dimensional AlN material layers with different thicknesses.

[0049] Step 4: First, spin-coat positive photoresist for 50s with a spin coater at a speed of 4600rpm rpm, perform pre-baking (heat treatment at 75 °C for 4min), expose with a deep ultraviolet light source for 15s, develop (time is 60s), and perform reactive ion etching treatment with plasma for 3min, dry with hot nitrogen for 4min. After evaporating the electrodes, ultrasonically vibrate in hot acetone for 8 minutes to remove the electrodes in the photoresist area.

[0050] Step 5: Put the sample into an annealing furnace, set the annealing temperature to 550 °C, and the time to 10 minutes to obtain the detector.

[0051] Embodiment 2

[0052] A method for preparing low-dimensional AlN material on MoS2, comprising the following steps:

[0053] Step 1: After cleaning 200nm SiO2 / (101)Si, by chemical vapor deposition (CVD), take 0.04g molybdenum oxide powder and 0.12g sulfur powder, the growth distance is 18cm, the air pressure is maintained at atmospheric pressure, the growth time is 12 minutes, and the growth temperature is 720°C to obtain MoS2 / SiO2 / Si;

[0054] Step 2: Transfer the MoS2 / SiO2 / Si in Step 1 to electron beam evaporation, and use its general process method to achieve an Al layer evaporation of 6nm to obtain Al / MoS2 / SiO2 / Si;

[0055] Step 3: Transfer the Al / MoS2 / SiO2 / Si in Step 2 to plasma enhanced chemical vapor deposition (PECVD), introduce ammonia / nitrogen at 50scmm / 100sccm, the growth temperature is 800 - 900°C, the plasma intensity is 120W, the growth pressure is 50kpa, and the growth time is 25 minutes.

[0056] Step 4: First, spin-coat positive photoresist for 55s with a rotation speed of 4800rpm, perform pre-baking (heat treatment at 85°C for 5min), expose with deep ultraviolet light source for 17s, develop (time is 62s), and perform reactive ion etching treatment with plasma for 4min, dry with hot nitrogen for 5min. After evaporating the electrode, ultrasonically vibrate in hot acetone for 9 minutes to remove the electrode in the photoresist area.

[0057] Step 5: Put the sample into an annealing furnace, set the annealing temperature to 570°C, and the time is 12 minutes.

[0058] Example 3

[0059] A method for preparing low-dimensional AlN material on MoS2 and its application, comprising the following steps:

[0060] Step 1: After cleaning 200nm SiO2 / (101)Si, by chemical vapor deposition (CVD), take 0.06g molybdenum oxide powder and 0.15g sulfur powder, the growth distance is 20cm, the air pressure is maintained at atmospheric pressure, the growth time is 15 minutes, and the growth temperature is 750°C to obtain MoS2 / SiO2 / Si;

[0061] Step 2: Transfer the MoS2 / SiO2 / Si obtained in Step 1 to electron beam evaporation, and use its general process method to achieve an Al layer evaporation of 12nm to obtain Al / MoS2 / SiO2 / Si;

[0062] Step 3: Transfer the Al / MoS2 / SiO2 / Si in Step 2 to plasma enhanced chemical vapor deposition (PECVD), introduce ammonia / nitrogen at 50 scmm / 100 sccm, with a growth temperature of 900 °C, a plasma intensity of 150 W, a growth pressure of 100 kPa, and a growth time of 30 minutes.

[0063] Step 4: First, spin-coat a positive photoresist for 60 s using a spin coater at a rotation speed of 5000 rpm. After pre-baking (heat treatment at 95 °C for 5 min), deep ultraviolet light source exposure for 20 s, development (time of 65 s), and reactive ion etching treatment using plasma for 5 min, followed by drying with hot nitrogen for 6 min. After evaporating the electrodes, ultrasonically oscillate in hot acetone for 10 minutes to remove the electrodes in the photoresist area.

[0064] Step 5: Place the sample in an annealing furnace, set the annealing temperature to 600 °C, and the time to 15 minutes to obtain the detector.

[0065] As Figure 4 and Figure 5 shown, the performance graph of the AlN / MoS2 Schottky type deep ultraviolet photodetector prepared in the embodiment of the present invention under 280 nm ultraviolet light shows a self-powered effect, a very high deep ultraviolet light responsivity, and a fast response ability.

[0066] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of low-dimensional AlN material on MoS2, characterized in that, it includes: growing a silicon dioxide layer on a silicon substrate; after cleaning the silicon dioxide layer and the silicon substrate, preparing two-dimensional MoS2 material layers with different thicknesses by chemical vapor deposition to obtain MoS2 / SiO2 / Si; transferring MoS2 / SiO2 / Si to electron beam evaporation, and depositing Al layers with different thicknesses to obtain Al / MoS2 / SiO2 / Si; transferring Al / MoS2 / SiO2 / Si to plasma enhanced chemical vapor deposition (PECVD), introducing nitrogen and ammonia, and turning on the plasma radio frequency to realize the growth of low-dimensional AlN material layers with different thicknesses, so that the two-dimensional MoS2 material layer and the low-dimensional AlN material layer form a high Schottky barrier and an internal built-in electric field; preparing Ti / Au electrodes with different thicknesses, the electrodes include a first metal electrode and a second metal electrode, the first metal electrode is provided on the two-dimensional MoS2 material layer, and the second metal electrode is provided on the low-dimensional AlN material layer; annealing the structure after preparing the Ti / Au electrodes at different temperatures in an annealing furnace, so that the metal forms an ohmic contact with the low-dimensional AlN material layer and the two-dimensional MoS2 material layer.

2. The preparation method of low-dimensional AlN material on MoS2 according to claim 1, characterized in that, preparing two-dimensional MoS2 material layers with different thicknesses by chemical vapor deposition to obtain MoS2 / SiO2 / Si, specifically: taking 0.03 - 0.06 g of molybdenum oxide powder and 0.1 - 0.15 g of sulfur powder, the growth distance is 15 - 20 cm, the air pressure is maintained at atmospheric pressure, the growth time is 10 - 15 minutes, and the growth temperature is 700 - 750 °C.

3. The preparation method of low-dimensional AlN material on MoS2 according to claim 1, characterized in that, the thickness of the Al layer is 3 - 12 nm.

4. The preparation method of low-dimensional AlN material on MoS2 according to claim 1, characterized in that, during the growth of the low-dimensional AlN material layer: ammonia / nitrogen is 50 scmm / 100 sccm, the growth temperature is 800 - 900 °C, the plasma intensity is 100 - 150 W, the growth pressure is 10 - 100 kp, and the growth time is 20 - 30 minutes.

5. The preparation method of low-dimensional AlN material on MoS2 according to claim 1, characterized in that, the low-dimensional AlN material layer covers three-quarters of the two-dimensional MoS2 material layer.

6. The preparation method of low-dimensional AlN material on MoS2 according to claim 1, characterized in that, the thickness of the silicon dioxide layer is 150 - 200 nm.

7. The preparation method of low-dimensional AlN material on MoS2 according to claim 1, characterized in that, the thickness of the low-dimensional AlN material layer is 5 - 15 nm.

8. The preparation method of low-dimensional AlN material on MoS2 according to claim 1, characterized in that, the thickness of the two-dimensional MoS2 material layer is 1 - 5 nm.

9. The preparation method of low-dimensional AlN material on MoS2 according to claim 1, characterized in that, The first metal electrode and the second metal electrode are both a Ti metal layer and an Au metal layer stacked in sequence from bottom to top; the thicknesses of the Ti metal layer and the Au metal layer are 40-80 nm and 80-110 nm respectively.

10. The preparation method according to any one of claims 1-9 is applied to a deep ultraviolet photodetector.

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