A method for doping a gallium oxide thin film with metal by laser induction

Abstract

The present invention discloses a method for doping a gallium oxide thin film with a metal by laser induction, comprising the following steps: (1) evaporating a Sn metal layer or sputtering a Nb metal layer on the gallium oxide thin film; (2) irradiating the gallium oxide thin film with laser microscopy focusing of different wavelengths; (3) soaking and washing away the metal layer on the gallium oxide thin film with hydrochloric acid or hydrofluoric acid according to the metal evaporated or sputtered on the surface of the gallium oxide thin film; (4) washing away hydrochloric acid or hydrofluoric acid with deionized water; (5) putting the gallium oxide thin film washed with hydrochloric acid or hydrofluoric acid into a beaker filled with deionized water and cleaning it in an ultrasonic cleaner; (6) taking out the gallium oxide thin film after ultrasonic cleaning and drying it with nitrogen. The advantage of the present invention is that the method for doping a gallium oxide thin film by laser induction is to dope the gallium oxide thin film after the growth of the gallium oxide thin film, and the doping concentration can be regulated by changing the laser irradiation parameters and irradiation time.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor thin films, and particularly relates to a method for doping metals in gallium oxide thin films by laser induction. Background Art

[0002] Gallium oxide is a semiconductor material with an ultra-wide bandgap and has received extensive attention in recent years. Among them, β-Ga2O3 has been widely studied and utilized due to its excellent chemical stability and thermal stability. Compared with silicon carbide (3.3 eV) and gallium nitride (3.4 eV), gallium oxide has a larger bandgap, approximately 4.9 eV. At the same time, gallium oxide has a higher breakdown voltage of 8 MV / cm and a larger Baliga figure of merit than silicon carbide and gallium nitride. Gallium oxide has excellent thermal stability and very high transmittance in the visible light region. Due to its unique properties, gallium oxide has great application potential in ultraviolet detectors, field-effect transistors, Schottky diodes, and other high-power devices. In addition, gallium oxide can be used as a substrate for microelectronic devices and is a key technology to support the development of industries such as 5G communication and new energy vehicles. To enable gallium oxide to play an important role in these fields, it is essential to improve the electrical properties of gallium oxide materials through doping methods. Currently, conventional doping methods at home and abroad include pulsed laser deposition, optical floating zone method, magnetron sputtering deposition, chemical vapor deposition, etc. However, these doping methods are realized during the growth process of gallium oxide materials and cannot regulate the concentration of doping elements, which has certain limitations. Moreover, high-concentration doping is a difficult problem for gallium oxide materials. Summary of the Invention

[0003] Aiming at the above deficiencies of the prior art, the present invention invents a method for doping metals in gallium oxide thin films by laser induction.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for doping metals in gallium oxide thin films by laser induction includes the following steps:

[0006] (1) Evaporating an Sn metal layer or sputtering an Nb metal layer on the grown gallium oxide thin film;

[0007] (2) Irradiating the gallium oxide thin film with a laser microscope focused at different wavelengths for a period of time;

[0008] (3) Soaking and washing the metal layer on the gallium oxide thin film with hydrochloric acid or hydrofluoric acid according to the metal evaporated or sputtered on the surface of the gallium oxide thin film;

[0009] (4) Washing the gallium oxide thin film with the metal layer removed with deionized water to remove hydrochloric acid or hydrofluoric acid;

[0010] (5) Place the gallium oxide film washed with hydrochloric acid or hydrofluoric acid into a beaker filled with deionized water and clean it in an ultrasonic cleaner.

[0011] (6) After taking out the gallium oxide film cleaned ultrasonically, dry it with nitrogen.

[0012] Further, the Sn metal layer is deposited by a VZZ-300 high-vacuum resistance evaporation coating equipment, and the thickness of the deposited Sn metal layer is 35 nm.

[0013] Further, anneal the gallium oxide film deposited with the Sn metal layer at 100 - 200 °C in a nitrogen environment for 10 - 50 min. Annealing restores the crystal structure of the Sn metal layer and eliminates defects; nitrogen is used as a protective gas to prevent oxidation of the Sn metal layer.

[0014] Further, the substrate temperature of the high-vacuum resistance evaporation coating equipment is 70 - 90 °C, and the current is 120 - 150 A.

[0015] Further, the Nb metal layer is deposited by DC magnetron sputtering of a magnetron sputtering coater. First, pre-sputter for 2 min to remove the oxide layer on the Nb metal target, and then sputter for 3 min. The thickness of the sputtered Nb thin film is 24 nm.

[0016] Further, the working pressure of the magnetron sputtering coater is 0.7 - 0.9 Pa, and the sputtering current is 0.1 - 0.4 A. The magnitude of the working pressure affects the roughness of the Nb metal layer.

[0017] Further, when the pressure in the chamber of the magnetron sputtering coater is 3×10 -4 Pa, introduce argon. The flow rate of the introduced argon is 20 - 50 ml / min. Electrons collide with argon atoms under the action of an electric field, causing them to ionize and generate argon positive ions. The argon positive ions bombard the target surface with high energy under the action of the electric field, causing sputtering of the target material.

[0018] Further, in step (2), the wavelength of the laser micro-focus irradiation of the gallium oxide film is 213 - 325 nm; the time of single laser micro-focus irradiation is 1 - 30 min. The irradiation time can be selected as 1 min, 2 min, 5 min, 10 min, 15 min, 20 min, 30 min according to the specific situation of the experiment; under the induction of the laser, the oxygen-gallium bonds in the gallium oxide are broken, enabling impurity atoms to exchange with gallium atoms to achieve substitution doping.

[0019] Further, in step (3), the Sn metal layer is soaked and cleaned with hydrochloric acid with a mass fraction of 20%, and the Nb metal layer is soaked and cleaned with hydrofluoric acid with a mass fraction of 20%. Soaking with the corresponding acid can remove the Sn metal layer or the Nb metal layer.

[0020] Further, in step (5), the cleaning time of the ultrasonic cleaner is 20 - 50 min. Through the cleaning of the ultrasonic cleaner, hydrochloric acid or hydrofluoric acid on the surface of the gallium oxide thin film can be cleaned thoroughly.

[0021] The advantages of the present invention are as follows: The laser-induced doping method of gallium oxide thin film dopes the gallium oxide thin film after its growth, and the doping concentration can be regulated by changing the laser irradiation parameters and irradiation time. Specific Embodiments

[0022] Example 1

[0023] A method for laser-induced doping of a gallium oxide thin film with a metal includes the following steps: (1) Evaporate a Sn metal layer on the grown gallium oxide thin film; the Sn metal layer is evaporated using a VZZ-300 high-vacuum resistance evaporation coating equipment. The substrate temperature of the high-vacuum resistance evaporation coating equipment is 70 °C, the current is 120 A, and the thickness of the evaporated Sn metal layer is measured to be 35 nm with a step gauge; after evaporation, the gallium oxide thin film is rapidly annealed at 100 °C in a nitrogen environment for 50 min.

[0024] (2) Irradiate the gallium oxide thin film with a laser microfocus of wavelength 213 nm, and the single irradiation time is 1 min.

[0025] (3) Immerse and clean the Sn metal layer evaporated on the surface of the gallium oxide thin film with 20% hydrochloric acid by mass for 20 min. During the immersion cleaning process, the gallium oxide thin film needs to be completely submerged.

[0026] (4) Wash away the hydrochloric acid from the gallium oxide thin film with deionized water after removing the metal layer.

[0027] (5) Put the gallium oxide thin film washed with hydrochloric acid into a beaker filled with deionized water and clean it in an ultrasonic cleaner for 20 min;

[0028] (6) Take out the gallium oxide thin film after ultrasonic cleaning and dry it with nitrogen.

[0029] (7) Measure the concentration of doped Sn element by EDS to be 0.05%.

[0030] Example 2

[0031] A method for doping a metal into a gallium oxide thin film by laser induction, comprising the following steps: (1) Evaporating an Sn metal layer on the grown gallium oxide thin film; the Sn metal layer is evaporated by a VZZ-300 high-vacuum resistance evaporation coating equipment, the substrate temperature of the high-vacuum resistance evaporation coating equipment is 90 °C, the current is 150 A, and the thickness of the evaporated Sn metal layer is measured by a step profiler to be 35 nm; after evaporation, the gallium oxide thin film is rapidly annealed at 200 °C in a nitrogen environment for 10 min.

[0032] (2) Using a laser microscope with a wavelength of 266 nm to focus and irradiate the gallium oxide thin film, and the single irradiation time is 5 min.

[0033] (3) Immersing and cleaning the Sn metal layer evaporated on the surface of the gallium oxide thin film with 20% hydrochloric acid by mass for 20 min, and the gallium oxide thin film needs to be completely submerged during the immersion and cleaning process.

[0034] (4) Washing the hydrochloric acid from the gallium oxide thin film with deionized water.

[0035] (5) Placing the gallium oxide thin film washed with hydrochloric acid into a beaker filled with deionized water and cleaning it in an ultrasonic cleaner for 20 min.

[0036] (6) Taking out the gallium oxide thin film after ultrasonic cleaning and drying it with nitrogen.

[0037] (7) Measuring the concentration of doped Sn element by EDS to be 0.19%.

[0038] Example 3

[0039] A method for doping a metal into a gallium oxide thin film by laser induction, comprising the following steps: (1) Sputtering an Nb metal layer on the grown gallium oxide thin film; the Nb metal layer is sputtered by DC magnetron sputtering of a magnetron sputtering coater. When the pressure in the chamber of the magnetron sputtering coater is 3×10 -4 Pa, argon is introduced, the flow rate of the introduced argon is 20 ml / min, the sputtering working pressure is 0.7 Pa, and the current is 0.1 A; first pre-sputter for 2 min to remove the oxide layer on the Nb metal target, and then sputter for 3 min. The thickness of the sputtered Nb thin film is measured by a step profiler to be 24 nm.

[0040] (2) Using a laser microscope with a wavelength of 325 nm to focus and irradiate the gallium oxide thin film, and the single irradiation time is 20 min.

[0041] (3) Immersing and cleaning the Nb metal layer sputtered on the surface of the gallium oxide thin film with 20% hydrofluoric acid by mass for 20 min; the gallium oxide thin film needs to be completely submerged during the immersion and cleaning process. (2) Using a laser microscope with a wavelength of 266 nm to focus and irradiate the gallium oxide thin film, and the single irradiation time is 5 min.

[0033] (3) Immersing and cleaning the Sn metal layer evaporated on the surface of the gallium oxide thin film with 20% hydrochloric acid by mass for 20 min, and the gallium oxide thin film needs to be completely submerged during the immersion and cleaning process.

[0034] (4) Washing the hydrochloric acid from the gallium oxide thin film with deionized water.

[0035] (5) Placing the gallium oxide thin film washed with hydrochloric acid into a beaker filled with deionized water and cleaning it in an ultrasonic cleaner for 20 min.

[0036] (6) Taking out the gallium oxide thin film after ultrasonic cleaning and drying it with nitrogen.

[0037] (7) Measuring the concentration of doped Sn element by EDS to be 0.19%.

[0038] Example 3

[0039] A method for doping a metal into a gallium oxide thin film by laser induction, comprising the following steps: (1) Sputtering an Nb metal layer on the grown gallium oxide thin film; the Nb metal layer is sputtered by DC magnetron sputtering of a magnetron sputtering coater. When the pressure in the chamber of the magnetron sputtering coater is 3×10 -4 Pa, argon is introduced, the flow rate of the introduced argon is 20 ml / min, the sputtering working pressure is 0.7 Pa, and the current is 0.1 A; first pre-sputter for 2 min to remove the oxide layer on the Nb metal target, and then sputter for 3 min. The thickness of the sputtered Nb thin film is measured by a step profiler to be 24 nm.

[0040] (2) Using a laser microscope with a wavelength of 325 nm to focus and irradiate the gallium oxide thin film, and the single irradiation time is 20 min.

[0041] (3) Immersing and cleaning the Nb metal layer sputtered on the surface of the gallium oxide thin film with 20% hydrofluoric acid by mass for 20 min; the gallium oxide thin film needs to be completely submerged during the immersion and cleaning process.

[0042] (4) Wash the gallium oxide film with the metal layer removed with deionized water to remove hydrofluoric acid;

[0043] (5) Place the gallium oxide film with hydrofluoric acid removed into a beaker filled with deionized water and put it into an ultrasonic cleaner for cleaning for 20 min;

[0044] (6) Take out the gallium oxide film after ultrasonic cleaning and dry it with nitrogen.

[0045] (7) The concentration of doped Nb element measured by EDS is 0.11%.

[0046] Example 4

[0047] A method for doping a metal in a laser-induced gallium oxide film, comprising the following steps: (1) Sputter an Nb metal layer on the grown gallium oxide film; the Nb metal layer is deposited by DC magnetron sputtering of a magnetron sputtering coater. When the pressure in the cavity of the magnetron sputtering coater is 3×10 -4 Pa, introduce argon, the flow rate of the introduced argon is 50 ml / min, the sputtering working pressure is 0.9 Pa, and the current is 0.4 A; pre-sputter for 2 min first to remove the oxide layer on the Nb metal target, and then perform sputtering for 3 min. Use a step profiler to measure the thickness of the sputtered Nb film as 24 nm.

[0048] (2) Irradiate the gallium oxide film with a laser microfocus with a wavelength of 266 nm, and the single irradiation time is 30 min.

[0049] (3) Immerse and clean the sputtered Nb metal layer on the surface of the gallium oxide film with 20% hydrofluoric acid by mass for 20 min; during the immersion and cleaning process, the gallium oxide film needs to be completely submerged.

[0050] (4) Wash the gallium oxide film with the metal layer removed with deionized water to remove hydrofluoric acid;

[0051] (5) Place the gallium oxide film with hydrofluoric acid removed into a beaker filled with deionized water and put it into an ultrasonic cleaner for cleaning for 20 min;

[0052] (6) Take out the gallium oxide film after ultrasonic cleaning and dry it with nitrogen.

[0053] (7) The concentration of doped Nb element measured by EDS is 0.15%.

[0054] In step (2), when irradiating with micro-focused laser light, the size of the laser spot can be changed by adjusting the distance between the light-emitting position and the gallium oxide film, and the spot area can be adjusted to the minimum, and its diameter can reach the order of micrometers; the minimum spot can be observed by the camera provided with the micro-focusing device, and at this time, the laser power of the 266 laser through the micro-focusing device measured by the power meter is stable at about 5mW.

[0055] The beakers and deionized water used for soaking and cleaning in steps (3), (4) and (5) are all new.

[0056] Although the above describes and illustrates the specific embodiments of the present invention in detail, it should be noted that various changes and modifications can be made to the above embodiments without departing from the spirit of the present invention and the scope of the appended claims.

Claims

1. A method for doping a metal in a gallium oxide thin film induced by laser, characterized in that, It includes the following steps: (1) Evaporate an Sn metal layer or sputter an Nb metal layer on the grown gallium oxide thin film; (2) Use a laser with a wavelength of 213 - 325 nm for micro-focus irradiation of the gallium oxide thin film for 1 - 30 min; (3) Soak and wash away the metal layer on the gallium oxide thin film with hydrochloric acid or hydrofluoric acid according to the metal evaporated or sputtered on the surface of the gallium oxide thin film; (4) Wash away the hydrochloric acid or hydrofluoric acid on the gallium oxide thin film with deionized water after washing away the metal layer; (5) Place the gallium oxide thin film washed with hydrochloric acid or hydrofluoric acid in a beaker filled with deionized water and put it into an ultrasonic cleaner for cleaning; (6) Take out the gallium oxide thin film after ultrasonic cleaning and dry it with nitrogen; 2. The method for doping a metal into a gallium oxide thin film induced by laser according to claim 1, wherein The Sn metal layer is evaporated by a VZZ - 300 high-vacuum resistance evaporation coating equipment, and the thickness of the evaporated Sn metal layer is 35 nm.

3. A method for doping a metal into a gallium oxide thin film by laser induction according to claim 2, characterized in that, Anneal the gallium oxide thin film with the Sn metal layer evaporated thereon rapidly at 100 - 200 °C in a nitrogen environment for 10 - 50 min.

4. A method for doping a metal into a gallium oxide thin film by laser induction according to claim 3, characterized in that, The substrate temperature of the high-vacuum resistance evaporation coating equipment is 70 - 90 °C, and the current is 120 - 150 A.

5. A method for doping a metal into a gallium oxide thin film induced by laser according to claim 1, characterized in that, The Nb metal layer is deposited by DC magnetron sputtering of a magnetron sputtering coater. First, pre-sputter for 2 min to remove the oxide layer on the Nb metal target, and then sputter for 3 min. The thickness of the sputtered Nb thin film is 24 nm.

6. A method for doping a metal into a gallium oxide thin film by laser induction according to claim 5, characterized in that, The working pressure of the magnetron sputtering coater is 0.7 - 0.9 Pa, and the sputtering current is 0.1 - 0.4 A.

7. A method for doping a metal into a gallium oxide thin film by laser induction according to claim 6, characterized in that, When the chamber pressure of the magnetron sputtering coating machine is 3×10 -4 Pa, argon gas is introduced, and the argon gas flow rate is 20 - 50 ml / min.

8. A method for doping a metal into a gallium oxide thin film by laser induction according to claim 1, characterized in that, In step (3), the Sn metal layer is soaked and cleaned with hydrochloric acid with a mass fraction of 20%, and the Nb metal layer is soaked and cleaned with hydrofluoric acid with a mass fraction of 20%.

9. A method for doping a metal into a gallium oxide thin film induced by laser according to claim 1, characterized in that, In step (5), the cleaning time of the ultrasonic cleaner is 20 - 50 min.