GaN thin film, and preparation method and application thereof

Abstract

The application discloses a GaN thin film and a preparation method and application thereof. The preparation method of the GaN thin film comprises the following steps: 1) taking an AlN ceramic target as raw material, and adopting a pulse laser deposition process to deposit an AlN thin film on a substrate; or, first depositing an AlN thin film on the substrate, and then taking metal Mo and sulfur powder as raw material, and adopting a magnetron sputtering process to deposit a MoS2 thin film on the AlN thin film; 2) taking trimethylgallium, trimethylaluminum and ammonia as raw material, and adopting an organic metal chemical vapor deposition process to deposit a GaN thin film on the AlN thin film or the MoS2 thin film. The GaN thin film is prepared by combining low-temperature PLD and high-temperature MOCVD, and has the advantages of simple operation, low cost, suitability for mass production and the like, and the prepared GaN thin film is smooth in surface, controllable in thickness, good in crystallization, uniform in growth, and suitable for large-scale application in the fields of photoelectronic and microelectronic.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a GaN thin film and a preparation method and application thereof. Background Art

[0002] Gallium nitride (GaN) is a wide bandgap semiconductor material with a bandgap of up to 3.4eV. Devices made from it have the advantages of large photocurrent, high sensitivity, high RF power density, and high UV / visible light suppression rate, and have broad application prospects in the fields of photodetectors and transistors. Therefore, it is of great significance to prepare GaN films with uniform growth, controllable thickness and good crystallization. At present, the common method for preparing GaN films is metal organic chemical vapor deposition (MOCVD). This method has the advantages of relatively simple equipment, fast growth rate and short growth cycle. However, it also has problems such as high production cost and high dislocation density of the grown GaN films (poor uniformity of GaN films), which seriously limit the practical application of GaN materials in the fields of optoelectronics and microelectronics.

[0003] Therefore, it is of great significance to develop a simple, easy-to-operate, and low-cost method for preparing GaN thin films, and to prepare GaN films with controllable thickness, good crystallization, and uniform growth. Summary of the Invention

[0004] The purpose of the present invention is to provide a GaN thin film and a preparation method and application thereof.

[0005] The technical solution adopted by the present invention is:

[0006] A method for preparing a GaN thin film comprises the following steps:

[0007] 1) Using AlN ceramic target as raw material, AlN thin film is deposited on substrate by pulsed laser deposition process;

[0008] Alternatively, an AlN ceramic target is used as a raw material to deposit an AlN film on a substrate using a pulsed laser deposition process, and then metallic Mo and sulfur powder are used as raw materials to deposit a MoS2 film on the AlN film using a magnetron sputtering process;

[0009] 2) Using trimethylgallium, trimethylaluminum and ammonia as raw materials, a GaN film is deposited on an AlN film or a MoS2 film using an organic metal chemical vapor deposition process.

[0010] Preferably, the substrate in step 1) is one of a Si substrate, an Al2O3 substrate, a SiO2 / Si substrate, and an InGaN substrate.

[0011] Preferably, the substrate in step 1) is cleaned and annealed before use.

[0012] Preferably, the specific operation of the cleaning includes: first cleaning the substrate with an H2SO4-H2O2 aqueous solution, and then cleaning the substrate with a 3% to 7% HF solution by mass. The purpose of cleaning the substrate is to remove contaminants on the substrate surface.

[0013] Preferably, the annealing treatment is performed at a temperature of 750° C. to 950° C. for 50 to 70 minutes. The annealing treatment is used to remove residual contaminants on the surface of the substrate.

[0014] Preferably, the operating parameters of the pulsed laser deposition process (PLD) in step 1) include: substrate temperature of 250°C to 450°C, background pressure of 1mTorr to 4mTorr, laser wavelength of 230nm to 270nm, laser energy of 200mJ to 1000mJ, and plasma generator power of 400W to 500W.

[0015] Preferably, the thickness of the AlN film in step 1) is 80 nm to 120 nm.

[0016] Preferably, the operating parameters of the magnetron sputtering process in step 1) include: a deposition temperature of 600°C to 700°C.

[0017] Preferably, the thickness of the MoS2 film in step 1) is 3 nm to 5 nm. By depositing MoS2 on the AlN film by magnetron sputtering, a surface with better lattice compatibility with the GaN can be obtained, alleviating the lattice mismatch problem and ultimately achieving higher uniformity of the GaN film prepared using the metal organic chemical vapor deposition process.

[0018] Preferably, the operating parameters of the metal organic chemical vapor deposition (MOCVD) process in step 2) include: a deposition temperature of 990° C. to 1090° C., and a deposition time of 25 min to 45 min.

[0019] Preferably, in step 2), the deposition rate of the GaN film is 3 μm / h to 20 μm / h.

[0020] Preferably, the thickness of the GaN film in step 2) is 1 μm to 5 μm.

[0021] A GaN thin film is produced by the above-mentioned production method.

[0022] Preferably, the GaN film is formed by stacking triangular GaN nanosheets.

[0023] Preferably, the GaN thin film is a continuous thin film.

[0024] Preferably, the GaN thin film is a single crystal thin film.

[0025] An electronic product comprising the GaN thin film.

[0026] Preferably, the electronic product is a field effect transistor.

[0027] The beneficial effects of the present invention are as follows: the present invention organically combines low-temperature PLD and high-temperature MOCVD to prepare GaN thin films, which has the advantages of being simple and easy to operate, low cost, and suitable for mass production. The prepared GaN thin films have a smooth surface, controllable thickness (the thickness can be adjusted within the range of 1μm to 5μm), good crystallization, and uniform growth (dislocation density is significantly reduced), and are suitable for large-scale application in the optoelectronics and microelectronics fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the pulsed laser deposition process in the embodiment.

[0029] Figure 2 Schematic diagram of the metal organic chemical vapor deposition process in the embodiment.

[0030] Figure 3 This is the XRD pattern of the GaN film in Example 1.

[0031] Figure 4 This is an AFM image of the GaN film in Example 1.

[0032] Figure 5 This is the SEM image of the GaN film in Example 1.

[0033] Figure 6 This is the XRD pattern of the GaN film in Example 2.

[0034] Figure 7 Schematic diagram of the magnetron sputtering process in Example 3.

[0035] Figure 8 Schematic diagram of the structure of the thin film grown on the Si substrate in Example 3.

[0036] Figure 9 This is the XRD pattern of the GaN film in Example 3.

[0037] Figure 10 This is the AFM image of the GaN film in Example 3.

[0038] Figure 11 This is the SEM image of the GaN film in Example 3.

[0039] Figure 12 This is the XRD pattern of the GaN film in Example 4.

[0040] Figure 13 This is the SEM image of the GaN film in Example 4. DETAILED DESCRIPTION

[0041] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0042] Example 1:

[0043] A GaN thin film, the preparation method of which is as follows:

[0044] 1) A Si substrate (square, 2 cm × 2 cm in size) was first cleaned with a H2SO4-H2O2 aqueous solution (the mass ratio of H2SO4, H2O2, and water was 3:1:1) for 3 min, then cleaned with a 5% HF solution for 3 min, and then placed in a pulsed laser deposition device and annealed at 750°C for 50 min. A radio frequency plasma generator was used to generate nitrogen plasma, and K r F excimer laser ablation sintering AlN ceramic target deposited AlN film with thickness of 100nm on substrate. The operating parameters of pulsed laser deposition process were: substrate temperature of 250℃, background pressure of 1mTorr, laser wavelength of 248nm, laser energy of 200mJ, and power of RF plasma generator of 400W (schematic diagram of pulsed laser deposition process is shown in Figure 2). Figure 1 shown);

[0045] 2) The Si substrates with AlN thin films deposited thereon obtained in step 1) (two substrates placed opposite each other) were placed in a heating furnace (model OTF-1200X, Hefei Kejing Materials Technology Co., Ltd.), and 0.2 g of trimethylgallium (TMGa) and 0.2 g of trimethylaluminum (TMAl) were placed in the heating furnace. The distance between trimethylgallium and trimethylaluminum and the Si substrate was L1, and the distance between the Si substrate and the edge of the heating furnace was L2. The parameters of the heating furnace were set as follows: reaction temperature T = 990°C; heating rate The rate is 20℃ / min; when the temperature in the heating furnace reaches 800℃, the gas is introduced, the reaction gas pressure p=1000Pa; the N2 flow rate is 15sccm; the NH3 flow rate is 30sccm; L1=12cm; L2=5.5cm; the reaction time is 35min; the substrate spacing d=60mm, the heating furnace is started, and a mixture of N2 and NH3 is introduced from the gas inlet on one side of the heating furnace to deposit a GaN film on the AlN film (the schematic diagram of the metal organic chemical vapor deposition process is shown in FIG). Figure 2 shown).

[0046] Performance testing:

[0047] The X-ray diffraction (XRD) pattern of the GaN film in this embodiment is shown in FIG. Figure 3As shown, the atomic force microscope (AFM) image of the GaN film in this embodiment is as follows Figure 4 As shown, the scanning electron microscope (SEM) image of the GaN film in this embodiment is as follows Figure 5 shown.

[0048] Depend on Figure 3 and Figure 4 It can be seen that a GaN thin film was indeed prepared in this embodiment, and the purity of the GaN thin film was relatively high.

[0049] Depend on Figure 5 It can be seen that the GaN film in this embodiment is a continuous single crystal film formed by stacking triangular GaN nanosheets. The film has a thickness of 2 μm, a roughness of 0.54 nm, and a half-height width of 159 arcsec.

[0050] Example 2:

[0051] A GaN thin film, the preparation method of which is as follows:

[0052] 1) A Si substrate (square, 2 cm × 2 cm in size) was first cleaned with an H2SO4-H2O2 aqueous solution (the mass ratio of H2SO4, H2O2, and water was 3:1:1) for 3 min, then cleaned with a 5% HF solution for 3 min, and then placed in a pulsed laser deposition apparatus (same as in Example 1) and annealed at 950°C for 70 min. A radio frequency plasma generator was then used to generate nitrogen plasma, and K r An AlN film with a thickness of 100 nm was deposited on a substrate by ablating and sintering an AlN ceramic target using an F excimer laser. The operating parameters of the pulsed laser deposition process were: substrate temperature of 450°C, background pressure of 2 mTorr, laser wavelength of 248 nm, laser energy of 300 mJ, and RF plasma generator power of 500 W.

[0053] 2) The Si substrate on which the AlN film was deposited obtained in step 1) was placed, and then 0.15 g of trimethylgallium (TMGa) and 0.15 g of trimethylaluminum (TMAl) were placed in a heating furnace (same as in Example 1), with the distance between the trimethylgallium and trimethylaluminum and the Si substrate being L1, and the distance between the Si substrate and the edge of the heating furnace being L2. The parameters of the heating furnace were set as follows: reaction temperature T = 1040°C; heating rate: 20°C / min; gas was introduced when the temperature in the heating furnace reached 800°C, reaction gas pressure p = 2000 Pa; N2 flow rate: 20 sccm; NH3 flow rate: 40 sccm; L1 = 15 cm; L2 = 4 cm; reaction time: 30 min; substrate spacing d = 80 mm, the heating furnace was started, and a mixture of N2 and NH3 was introduced from the gas inlet on one side of the heating furnace to deposit a GaN film on the AlN film.

[0054] Performance testing:

[0055] The XRD pattern of the GaN film in this embodiment is as follows: Figure 6 shown.

[0056] Depend on Figure 6 It can be seen that a GaN thin film was indeed prepared in this embodiment, and the purity of the GaN thin film was relatively high.

[0057] Furthermore, tests (using the same testing method as in Example 1) have shown that the GaN film in this embodiment is a continuous single crystal film formed by stacking triangular GaN nanosheets, with a thickness of 3 μm and a half-height width of 168 arcsec.

[0058] Example 3:

[0059] A GaN thin film, the preparation method of which is as follows:

[0060] 1) A Si substrate (square, 2 cm × 2 cm in size) was first cleaned with an H2SO4-H2O2 aqueous solution (the mass ratio of H2SO4, H2O2, and water was 3:1:1) for 3 min, then cleaned with a 5% HF solution for 3 min, and then placed in a pulsed laser deposition apparatus (same as in Example 1) and annealed at 800°C for 55 min. A radio frequency plasma generator was then used to generate nitrogen plasma, and K r An AlN film with a thickness of 100 nm was deposited on a substrate by ablating and sintering an AlN ceramic target using an F excimer laser. The operating parameters of the pulsed laser deposition process were: substrate temperature of 400°C, background pressure of 3 mTorr, laser wavelength of 248 nm, laser energy of 250 mJ, and power of the RF plasma generator of 500 W.

[0061] 2) The Si substrate with AlN film deposited thereon obtained in step 1) was placed in a CVD tube furnace, with metal Mo as target material and Ar gas as supply gas and the gas pressure maintained at 0.7 Pa, and magnetron sputtering was performed (the schematic diagram of the magnetron sputtering process is shown in FIG). Figure 7 The deposition of metallic Mo on non-polar a-plane GaN was carried out by the method shown in FIG. 2 , using sulfur powder (200 mg) as the S element source and N2 as the carrier gas. The S powder was converted into a gaseous precursor by heating in a CVD tube furnace, and 10 sccm of N2 was introduced to transfer the S gas to the surface of the AlN film. The film was then kept at 680°C for 1 hour to form a MoS2 film with a thickness of 4 nm.

[0062] 3) The Si substrate (two substrates placed opposite each other) on which the MoS2 film was deposited obtained in step 2) was placed in a heating furnace (same as in Example 1), and then 0.1 g of trimethylgallium (TMGa) and 0.1 g of trimethylaluminum (TMAl) were placed in the heating furnace, with the distance between trimethylgallium and trimethylaluminum and the Si substrate being L1, and the distance between the Si substrate and the edge of the heating furnace being L2. The parameters of the heating furnace were set as follows: reaction temperature T = 1000°C; heating rate of 20°C / min; gas was introduced when the temperature in the heating furnace reached 800°C, reaction gas pressure p = 5000 Pa; N2 flow rate of 12 sccm; NH3 flow rate of 20 sccm; L1 = 16 cm; L2 = 4.5 cm; reaction time of 25 min; substrate spacing d = 80 mm, the heating furnace was started, and a mixture of N2 and NH3 was introduced from the gas inlet on one side of the heating furnace to deposit a GaN film on the MoS2 film (the structural schematic diagram of the film grown on the Si substrate is shown in FIG. 2 ). Figure 8 shown).

[0063] Performance testing:

[0064] The XRD pattern of the GaN film in this embodiment is as follows: Figure 9 As shown, the AFM image of the GaN film in this embodiment is as follows Figure 10 As shown, the SEM image of the GaN film in this embodiment is as follows Figure 11 shown.

[0065] Depend on Figure 9 and Figure 10 It can be seen that a GaN thin film was indeed prepared in this embodiment, and the purity of the GaN thin film was relatively high.

[0066] Depend on Figure 11 It can be seen that the GaN film in this embodiment is a continuous single crystal film formed by stacking triangular GaN nanosheets. The film has a thickness of 5 μm, a roughness of 0.49 nm, and a half-height width of 205 arcsec.

[0067] Example 4:

[0068] A GaN thin film, the preparation method of which is as follows:

[0069] 1) A Si substrate (square, 2 cm × 2 cm in size) was first cleaned with an H2SO4-H2O2 aqueous solution (the mass ratio of H2SO4, H2O2, and water was 3:1:1) for 3 min, then cleaned with a 5% HF solution for 3 min, and then placed in a pulsed laser deposition apparatus (same as in Example 1), annealed at 850°C for 60 min, and then nitrogen plasma was generated using a radio frequency plasma generator. K rAn AlN film with a thickness of 100 nm was deposited on a substrate by ablating and sintering an AlN ceramic target using an F excimer laser. The operating parameters of the pulsed laser deposition process were: substrate temperature of 350°C, background pressure of 4 mTorr, laser wavelength of 248 nm, laser energy of 250 mJ, and RF plasma generator power of 500 W.

[0070] 2) The Si substrate with the AlN film deposited thereon obtained in step 1) was placed in a CVD tube furnace (same as in Example 3), and metallic Mo was used as a target. Ar gas was used as a supply gas and the gas pressure was maintained at 0.7 Pa. Metal Mo was deposited on the non-polar a-plane GaN by magnetron sputtering. Sulfur powder (200 mg) was used as the S element source and N2 was used as a carrier gas. The S powder was converted into a gaseous precursor by heating in a CVD tube furnace. 10 sccm of N2 was introduced to transfer the S gas to the surface of the AlN film, and then the film was kept at 680°C for 1 hour to form a MoS2 film with a thickness of 3 nm.

[0071] 3) The Si substrate (two substrates placed opposite each other) deposited with the MoS2 film obtained in step 2) is placed in a heating furnace (same as in Example 1), and then 0.1g of trimethylgallium (TMGa) and 0.1g of trimethylaluminum (TMAl) are placed in the heating furnace, the distance between trimethylgallium and trimethylaluminum and the Si substrate is L1, and the distance between the Si substrate and the edge of the heating furnace is L2. The parameters of the heating furnace are set: reaction temperature T = 1000°C; heating rate is 20°C / min; when the temperature in the heating furnace is 800°C, gas is started, reaction gas pressure p = 1000Pa; N2 flow rate is 12sccm; NH3 flow rate is 15sccm; L1 = 20cm; L2 = 5cm; reaction time is 30min; substrate spacing d = 80mm, start the heating furnace, and pass a mixed gas of N2 and NH3 from the gas inlet on one side of the heating furnace to deposit a GaN film on the MoS2 film.

[0072] Performance testing:

[0073] The XRD pattern of the GaN film in this embodiment is as follows: Figure 12 As shown, the SEM image of the GaN film in this embodiment is as follows Figure 13 shown.

[0074] Depend on Figure 12 It can be seen that a GaN thin film was indeed prepared in this embodiment, and the purity of the GaN thin film was relatively high.

[0075] Depend on Figure 13 It can be seen that the GaN film in this embodiment is a continuous single crystal film formed by stacking triangular GaN nanosheets. The thickness of the film is 4 μm and the half-height width is 189 arcsec.

[0076] Example 5:

[0077] A GaN thin film is prepared in the same manner as in Example 4 except that the substrate spacing d in step 3) is adjusted from 80 mm to 60 mm.

[0078] After testing (the testing method is the same as that of Example 1), the GaN film in this embodiment is a continuous single crystal film formed by stacking triangular GaN nanosheets together, and the thickness of the film is 3 μm.

[0079] Example 6:

[0080] A GaN thin film is prepared in the same manner as in Example 4 except that the substrate spacing d in step 3) is adjusted from "80 mm" to "85 mm".

[0081] After testing (the testing method is the same as that of Example 1), the GaN film in this embodiment is a continuous single crystal film formed by stacking triangular GaN nanosheets together, and the thickness of the film is 4 μm.

[0082] Example 7:

[0083] A GaN thin film is prepared in the same manner as in Example 4 except that the substrate spacing d in step 3) is adjusted from 80 mm to 100 mm.

[0084] After testing (the testing method is the same as that of Example 1), the GaN film in this embodiment is a continuous single crystal film formed by stacking triangular GaN nanosheets together, and the thickness of the film is 3 μm.

[0085] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a GaN thin film, characterized in that: The following steps are involved: 1) Using AlN ceramic target as raw material, AlN film is deposited on substrate by pulsed laser deposition process, and then Mo and sulfur powder are used as raw materials to deposit MoS2 film on AlN film by magnetron sputtering process; 2) Using trimethylgallium, trimethylaluminum and ammonia as raw materials, a GaN film is deposited on the MoS2 film using an organic metal chemical vapor deposition process; Step 1) The operating parameters of the magnetron sputtering process include: a deposition temperature of 600° C. to 700° C.; Step 1) The thickness of the MoS2 film is 3nm to 5nm; Step 2) The operating parameters of the metal organic chemical vapor deposition process include: a deposition temperature of 990° C. to 1090° C., and a deposition time of 25 min to 45 min; Step 2) The thickness of the GaN film is 1 μm to 5 μm.

2. The method for preparing a GaN thin film according to claim 1, wherein: Step 1) The substrate is one of a Si substrate, an Al2O3 substrate, a SiO2 / Si substrate, and an InGaN substrate.

3. The method for preparing a GaN thin film according to claim 1 or 2, wherein: Step 1) The operating parameters of the pulsed laser deposition process include: substrate temperature of 250° C. to 450° C., background pressure of 1 mTorr to 4 mTorr, laser wavelength of 230 nm to 270 nm, laser energy of 200 mJ to 1000 mJ, and plasma generator power of 400 W to 500 W.

4. The method for preparing a GaN thin film according to claim 1 or 2, wherein: Step 1) The thickness of the AlN film is 80 nm to 120 nm.

5. A GaN thin film, characterized in that: Prepared by the preparation method according to any one of claims 1 to 4.

6. An electronic product, characterized in that: Comprising the GaN thin film according to claim 5.

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