CN101748382B - Method of growing GaN-based luminescent crystalline membrane for molecular beam epitaxy - Google Patents

Abstract

The invention discloses a method for growing a GaN-based luminescent crystal film by molecular beam epitaxy. During the growth process, rare earth ions are doped to replace part of the lattice sites of Ga ³⁺ . It is characterized in that: the raw material formula of the GaN crystal film Group III element boron or aluminum is doped in proportion in the growth process, and the group III element boron or aluminum enters the GaN lattice in the form of trivalent ions to adjust the ion radius difference between rare earth ions and Ga ³⁺ ; The molar ratio of the raw material formula is: Ga: Re: A=(1-xy): x: y, wherein Re represents rare earth metal, A represents group III element boron or aluminum, 0.1%≤x≤10.0%, 0.1x≤y ≤ x. Since the present invention adopts group III elements boron or aluminum and rare earth metals to be co-doped in a certain ratio, it can greatly improve the GaN caused by the large radius mismatch between Re ³⁺ and Ga ³⁺ . The crystal lattice of the crystal film is distorted, thereby improving the luminous performance of the GaN crystal film.

Description

Method for growing GaN-based light-emitting crystal film by molecular beam epitaxy

technical field

The invention relates to a method for growing a GaN film material, in particular to a method for MBE growing a GaN crystal film doped with rare earth ions. the

Background technique

The third-generation semiconductor material GaN and its related devices have broad application prospects in optical display, optical storage, laser printing, optical lighting, medical and military fields, so the third-generation semiconductor material represented by GaN is known as IT A new engine for the industry. the

GaN is a wide band gap semiconductor with a band gap up to 3.4eV, so various rare earth ions can be doped into GaN without luminescence quenching. The luminescence band of rare earth ions can cover the region from ultraviolet to infrared, and the luminescence transition of rare earth ions mainly occurs between the partially filled 4f energy levels, which is less affected by the crystal field environment, the luminescence peak is sharp, and its color purity is relatively high. high. At present, the use of MBE to prepare GaN films doped with rare earth ions has received widespread attention from researchers ("Rare-Earth-Doped GaN: Growth, Properties, and Fabrication of Electroluminescent Devices", published in IEEEJournal of Selected Topics In Quantum Electronics, 2002, 8(4):749), the GaN film shows great application prospects in the fields of electroluminescent devices, flat panel displays, laser diodes and other fields. the

After the rare earth ions are doped into the GaN matrix, they generally replace the lattice sites of Ga ³⁺ , and the radius of the rare earth ions is generally larger than that of Ga ³⁺ . The radius of Ga ³⁺ is 62pm, while the radius of the rare earth ions is 103.4 pm (Ce ³⁺ ) and 84.8pm (Lu ³⁺ ). Therefore, from the perspective of ionic radius matching, the doping of rare earth ions will cause large lattice distortion. Undoubtedly, the generation of such lattice distortion will introduce more point defects in the crystal film, thereby reducing the Luminescence properties of GaN crystal films.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for growing GaN-based light-emitting crystal films by molecular beam epitaxy, which solves the problem of the large ion gap between the doped rare earth ions and Ga ³⁺ in the prior art. The problem of lattice distortion caused by radius mismatch can improve the luminescent performance of GaN-based crystal film doped with rare earth ions.

For realizing the above object, technical solution of the present invention is:

In general: the method for growing a GaN-based light-emitting crystal film by molecular beam epitaxy, doping rare earth ions during the growth process, replacing part of the lattice sites of Ga ³⁺ , is characterized in that: in the raw material formula of the GaN crystal film, according to Proportional doping of group III element boron or aluminum, during the growth process, the group III element boron or aluminum enters the GaN lattice in the form of trivalent ions, and adjusts the ionic radius difference between rare earth ions and Ga ³⁺ ; the raw material The formula molar ratio is: Ga: Re: A = (1-xy): x: y, where Re represents rare earth metals, including cerium Ce, praseodymium Pr, neodymium Nd, promethium Pm, samarium Sm, europium Eu, gadolinium Gd, terbium Any one or more of Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb, lutetium Lu; A means group III element boron or aluminum; 0.1%≤x≤10.0%, 0.1x≤y≤ x.

Specifically: the method for molecular beam epitaxy growth GaN-based light-emitting crystal film is characterized in that comprising steps: 1, by molar ratio Ga: Re: A=(1-xy): x: y, 0.1%≤x≤10.0% , 0.1x≤y≤x Weigh the raw materials Ga, Re and A, and place them in the evaporation pools of the device respectively, where A represents the group III element boron or aluminum; II. Place the GaN-based substrate in the molecular beam epitaxy chamber , vacuumize and heat-treat the GaN-based substrate, keeping the temperature at 550°C-600°C; III. Control the temperature of each evaporation pool to evaporate each raw material element in proportion, and control the growth rate at 0.5-1μm/h; and pass Radio frequency plasma generates atomic nitrogen; Ⅳ. Naturally cool the substrate and each evaporation pool, and then empty the molecular beam epitaxy chamber to obtain a GaN crystal film co-doped with rare earth ions and B ³⁺ or Al ³⁺ .

Further, in the aforementioned method for growing a GaN-based light-emitting crystal film by molecular beam epitaxy, in step III, the temperature of the Ga evaporation pool is controlled at 850°C-945°C, the temperature of the Re evaporation pool is controlled at 500°C-1100°C, and the group III element boron or aluminum The temperature of the evaporation pool is controlled at 800°C-1100°C; the GaN-based substrate in step II includes any one of silicon with GaN film grown, sapphire with GaN film grown or GaN bulk. the

The method for growing a GaN-based luminescent crystal film by molecular beam epitaxy of the present invention has the remarkable advantages of:

Due to the co-doping of group III elements boron or aluminum and rare earth metals in a certain ratio, the GaN crystal film caused by the large radius mismatch between Re ³⁺ and Ga ³⁺ can be greatly improved The lattice is distorted, thereby improving the luminescent performance of the GaN crystal film.

Detailed ways

The radii of B ³⁺ and Al ³⁺ are 20pm and 50pm respectively, so if B ³⁺ or Al ³⁺ and rare earth ions of group III elements are co-doped in the GaN crystal film in an appropriate ratio, it will be able to Improve the lattice distortion of the crystal film; and because B ³⁺ or Al ³⁺ is a neutral component, doping a small amount of B ³⁺ or Al ³⁺ will not have adverse effects on the luminescent performance of the GaN crystal film.

Example 1:

In this example, x=0.1%, y=0.01%, Re is erbium Er, a rare earth metal, and A is boron (B). Put the above-mentioned weighed raw materials into different evaporation pools in the molecular beam epitaxy (hereinafter referred to as MBE) device, select sapphire with a GaN film as the substrate, control the temperature of the Ga evaporation pool at 900 ° C, and control the temperature of the Er evaporation pool at 850 °C. °C, the temperature of the crystal B evaporation pool was controlled at 900 °C. And atomic nitrogen is generated by radio frequency plasma. After obtaining a film with a thickness of 5 μm, the substrate and the evaporation pools were naturally cooled, and the Er ³⁺ and B ³⁺ co-doped GaN crystal film could be taken out after the MBE was emptied. Compared with the GaN crystal film doped with Er ³⁺ at the same concentration without co-doping B ³⁺ , the fluorescence intensity is enhanced by 5%-20%.

Example 2:

In this example, x=10%, y=1%, Re is erbium Er, a rare earth metal, and A is aluminum (Al). Put the above-mentioned weighed raw materials into different evaporation pools in the MBE device. The substrate is selected to grow silicon with GaN film. The temperature is controlled at 980°C. And atomic nitrogen is generated by radio frequency plasma. After obtaining a film with a thickness of 5 μm, the substrate and the evaporation pools were naturally cooled, and the Er ³⁺ and Al ³⁺ co-doped GaN crystal film could be taken out after the MBE was emptied. Compared with the GaN crystal film doped with Er ³⁺ at the same concentration without co-doping Al ³⁺ , the fluorescence intensity is enhanced by 5%-20%.

Example 3:

In this example, x=5%, y=0.5%, Re is the rare earth metal erbium Er, and A is the metal aluminum (Al). Put the above-mentioned weighed raw materials into different evaporation pools in the MBE device, and select the GaN block grown by HVPE as the substrate. The temperature is controlled at 930°C. And atomic nitrogen is generated by radio frequency plasma. After obtaining a film with a thickness of 5 μm, the substrate and the evaporation pools were naturally cooled, and the Er ³⁺ and Al ³⁺ co-doped GaN crystal film could be taken out after the MBE was emptied. Compared with the GaN crystal film doped with Er ³⁺ at the same concentration without co-doping Al ³⁺ , the fluorescence intensity is enhanced by 5%-20%.

Example 4:

In this example, x=5%, y=0.5%, Re is thulium Tm, a rare earth metal, and A is aluminum (Al). Put the above-mentioned weighed raw materials into different evaporation pools in the MBE device. The GaN bulk grown by HVPE is selected as the substrate. The temperature is controlled at 930°C. And atomic nitrogen is generated by radio frequency plasma. After obtaining a film with a thickness of 5 μm, the substrate and each evaporation pool are naturally cooled, and the Tm ³⁺ and Al ³⁺ co-doped GaN crystal film can be taken out after the MBE is emptied. Compared with the GaN crystal film doped with Tm ³⁺ at the same concentration without co-doping Al ³⁺ , the fluorescence intensity is enhanced by 5%-20%.

Embodiment 5:

In this example, x=5%, y=0.5%, Re is the rare earth metal praseodymium Pr, and A is the metal aluminum (Al). Put the above-mentioned weighed raw materials into different evaporation pools of the MBE device. The substrate is a GaN block grown by HVPE. The temperature is controlled at 900°C. And atomic nitrogen is generated by radio frequency plasma. After obtaining a film with a thickness of 5 μm, the substrate and the evaporation pools were naturally cooled, and the GaN crystal film co-doped with pr ³⁺ and Al ³⁺ could be taken out after the MBE was emptied. Compared with the GaN crystal film doped with pr ³⁺ at the same concentration without co-doping Al ³⁺ , the fluorescence intensity is enhanced by 5%-20%.

Embodiment 6:

In this example, x=5%, y=0.5%, Re is the rare earth metal europium Eu, and A is the metal aluminum (Al). The above-mentioned weighed raw materials were placed in different evaporation pools of the MBE device. The substrate was GaN blocks grown by HVPE. The temperature of the Ga evaporation pool was controlled at 900 ° C, the Eu evaporation pool was controlled at 570 ° C, and the metal Al evaporation pool The temperature is controlled at 900°C. And atomic nitrogen is generated by radio frequency plasma. After obtaining a film with a thickness of 5 μm, the substrate and the evaporation pools were naturally cooled, and the Eu ³⁺ and Al ³⁺ co-doped GaN crystal film could be taken out after the MBE was emptied. Compared with the GaN crystal film doped with Eu ³⁺ at the same concentration without co-doping Al ³⁺ , the fluorescence intensity increases by 5%-20%.

Claims (5)

1. the method for growing GaN-based luminescent crystalline membrane for molecular beam epitaxy, doping with rare-earth ions in process of growth replaces part Ga ³⁺Lattice site, it is characterized in that: in the composition of raw materials of said GaN crystal film, mix III family element boron or aluminium in proportion, get into the GaN lattice, allotment rare earth ion and Ga with the form of trivalent ion at the family's element boron of III described in the process of growth or aluminium ³⁺Between ionic radius poor; Said composition of raw materials molar ratio is: Ga: Re: A=(1-x-y): x: y, and wherein Re representes rare earth metal, A representes III family element boron or aluminium, 0.1%≤x≤10.0%, 0.1x≤y≤x.

2. the method for growing GaN-based luminescent crystalline membrane for molecular beam epitaxy according to claim 1 is characterized in that: said rare earth metal comprises among cerium Ce, praseodymium Pr, neodymium Nd, promethium Pm, samarium Sm, europium Eu, gadolinium Gd, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb, the lutetium Lu any one or multiple using with.

3. the method for growing GaN-based luminescent crystalline membrane for molecular beam epitaxy is characterized in that comprising step:

I, Ga: Re: A=(1-x-y) in molar ratio: x: y, 0.1%≤x≤10.0%, 0.1x≤y≤x raw materials weighing Ga, Re and A are positioned over respectively in each evaporation tank in the device, and wherein A representes III family element boron or aluminium;

II, GaN base substrate is placed the molecular beam epitaxy chamber, vacuumize and GaN base substrate is heat-treated, maintain the temperature at 550 ℃-600 ℃;

III, regulate and control each evaporation tank temperature, each raw material element is evaporated in proportion, control growing speed is at 0.5-1 μ m/h; And through radio-frequency plasma generation Nitrogen Atom;

IV, naturally cooling substrate and each evaporation tank with the emptying of molecular beam epitaxy chamber, promptly get rare earth ion and B again ³⁺Or Al ³⁺The GaN crystal film of mixing altogether.

4. the method for growing GaN-based luminescent crystalline membrane for molecular beam epitaxy according to claim 3; It is characterized in that: Ga evaporation tank temperature is controlled at 850 ℃-945 ℃ among the Step II I; Re evaporation tank temperature is controlled at 500 ℃-1100 ℃, and the evaporation tank temperature of III family element boron or aluminium is controlled at 800 ℃-1100 ℃.

5. the method for growing GaN-based luminescent crystalline membrane for molecular beam epitaxy according to claim 3 is characterized in that: the base of GaN described in Step II substrate comprises that growth has in the silicon of GaN film, sapphire that growth has the GaN film or the GaN block any one.