CN1482689A - MgIn2O4/MgO composite substrate material and preparation method thereof - Google Patents

Abstract

A MgIn ₂ O ₄ /MgO composite substrate material and a preparation method thereof, wherein the composite substrate material is composed of a MgIn ₂ O ₄ covering layer arranged on a MgO single crystal. The preparation method of the composite substrate material is: firstly, an In ₂ O ₃ thin film is prepared on a MgO single crystal substrate by a pulsed laser deposition method, and then, at a high temperature, a MgIn ₂ O ₄ covering layer is formed on the MgO single crystal substrate by a solid phase reaction of In ₂ O ₃ and MgO. The preparation process of the composite substrate material of the invention is simple and easy to operate, and the composite substrate (MgIn ₂ O ₄ /MgO) of this structure is suitable for the epitaxial growth of high-quality GaN.

Description

MgIn 2O 4/ MgO compound lining material and preparation method thereof

Technical field

The present invention relates to a kind of for the epitaxially grown MgIn of InN-GaN base blue-light semiconductor ₂O ₄/ MgO compound lining material and preparation method thereof.

Background technology

The broad-band gap III-V group iii v compound semiconductor material that with GaN is representative is receiving increasing concern, they will be at blue, green light LED (LEDs) and laser diode (LDs), high density information read-write, subsurface communication, deep quest, laser printing, biology and engineering in medicine, and ultrahigh speed microelectronic component and hyperfrequency microwave device aspect are with a wide range of applications.

Because GaN fusing point height, hardness is big, saturated vapor pressure is high, so want the GaN body monocrystalline of growing large-size to need high temperature and high pressure, Polish high pressure research center has made just under the high pressure of 1600 ℃ high temperature and 20kbar that bar is wide to be the SaN body monocrystalline of 5mm.Current, the technology of GaN body monocrystalline of growing large-size more immature, and growth is with high costs, from practical application quite long distance is arranged still.

Sapphire crystal (α-Al ₂O ₃), be easy to preparation, low price, and have the good characteristics such as high-temperature stability, α-Al ₂O ₃It is at present the most frequently used InN-GaN epitaxial substrate material (referring to Jpn.J.Appl.Phys., the 36th volume,, the 1568th page in 1997).

The MgO crystal belongs to cubic system, and NaCl type structure, lattice constant are 0.4126nm.Fusing point is 2800 ℃.Because the lattice mismatch of MgO crystal and GaN reaches 13%, and not enough stable in MOCVD atmosphere, thereby use less.

At present, typical GaN base blue-ray LED is made on Sapphire Substrate.Its structure is as follows from top to bottom: p-GaN/AlGaN barrier layer/InGaN-GaN quantumwells/AlGaN barrier layer/n-GaN/4um GaN.Because sapphire has high resistivity, so the n-type of device and p-type electrode must be drawn from the same side.This has not only increased the manufacture difficulty of device, has also increased the volume of device simultaneously.According to interrelated data, for the Sapphire Substrate of a slice 2 inches diameter size, present technology can only be produced about about 10,000 of GaN device, and if backing material has suitable conductivity, then when simplifying device making technics, its number can increase to present 3～4 times.

In sum, technology substrate (α-Al formerly ₂O ₃And MgO) the remarkable shortcoming that exists is:

(1) with α-Al ₂O ₃Make substrate, α-Al ₂O ₃And the lattice mismatch between the GaN makes the GaN film of preparation have higher dislocation density and a large amount of point defects up to 14%;

(2) because the lattice mismatch of MgO crystal and GaN reaches 13%, and stable inadequately in MOCVD atmosphere, thereby use less;

(3) above transparent oxide substrate is all non-conductive, and the element manufacturing difficulty is big, has also increased the volume of device simultaneously, has caused the waste of great deal of raw materials.

Summary of the invention

The technical problem to be solved in the present invention is to overcome the shortcoming of above-mentioned prior art, provides a kind of as the epitaxially grown MgIn of InN-GaN base blue-light semiconductor ₂O ₄/ MgO compound lining material and preparation method thereof.

MgIn of the present invention ₂O ₄/ MgO compound lining material is actually at the MgO monocrystalline and is provided with one deck MgIn ₂O ₄And consist of, this compound substrate is suitable for epitaxial growth high quality InV-GaN base blue-light semiconductor film.

MgIn ₂O ₄Belong to cubic system, spinel structure, lattice paprmeter is 0.8864nm, MgIn ₂O ₄Littler with the lattice mismatch of GaN (111), be 1.1%.But consider MgIn ₂O ₄Large scale bulk growth difficulty, the present invention proposes to utilize pulsed laser deposition (PLD:pulsed laserdeposition) technology and In ₂O ₃And the method for the solid phase reaction between the MgO generates MgIn in the MgO single crystalline substrate ₂O ₄Cover layer, thus MgIn obtained ₂O ₄/ MgO compound substrate.Here, the MgO monocrystalline was both participated in solid phase reaction as reactant, worked again the MgIn that supports on it ₂O ₄The effect of electrically conducting transparent thin layer.Compound substrate (the MgIn of this kind structure ₂O ₄/ MgO) be suitable for the epitaxial growth of high-quality GaN.

Basic thought of the present invention is:

A kind of MgIn ₂O ₄The preparation method of/MgO compound lining material mainly is to utilize the pulsed laser deposition method to prepare In in the MgO single crystalline substrate ₂O ₃Film then at high temperature, passes through In ₂O ₃With the solid phase reaction of MgO, form MgIn in the MgO single crystalline substrate ₂O ₄Cover layer.

MgIn of the present invention ₂O ₄The preparation method of/MgO compound lining material is characterized in that it comprises following concrete steps:

＜1〉prepares In in the MgO single crystalline substrate ₂O ₃Film: the MgO single crystalline substrate of will polish, cleaning is sent into the pulsed laser deposition system, and In is adopted in the In source ₂O ₃Target; Adopt the KrF excimer laser of pulsewidth 25-30ns (nanosecond), excitation wavelength is 248nm, and scioptics are with about 10J/cm ²Energy density optically focused, the In in optical window shines vacuum plant ₂O ₃Target, under the reaction atmosphere of oxygen enrichment, deposit In on heated MgO single crystalline substrate ₂O ₃Film;

＜2〉In ₂O ₃Solid phase reaction with MgO: with the In that obtains ₂O ₃/ MgO sample is put into annealing furnace, is warming up to 700～1500 ℃, in the reaction atmosphere of rich In, makes In ₂O ₃With MgO solid phase reaction taking place at high temperature, obtains MgIn ₂O ₄Cover layer forms MgIn ₂O ₄/ MgO compound lining material.

Described In ₂O ₃The purity of target is better than 99.999%.

Described In ₂O ₃During with the solid phase reaction of MgO, the optimum temperature in the annealing furnace is 1000 ℃.

Characteristics of the present invention are:

(1) proposed a kind of for the epitaxially grown MgIn of InN-GaN base blue-light semiconductor ₂O ₄Backing material, this substrate is compared with substrate formerly, and the lattice mismatch of itself and GaN (111) is littler, be 1.1%, and this material is the transparent conductive oxide material.

(2) the present invention proposes to utilize pulsed laser deposition (PLD) technology and In ₂O ₃And the solid phase reaction between the MgO generates MgIn in the MgO single crystalline substrate ₂O ₄Cover layer, thus MgIn obtained ₂O ₄/ MgO compound substrate, the preparation technology of this compound substrate is simple, easy to operate, the compound substrate (MgIn of this kind structure ₂O ₄/ MgO) be suitable for the epitaxial growth of high-quality GaN.

Description of drawings

Fig. 1 is the schematic diagram of pulsed laser deposition (PLD) system.

Embodiment

Fig. 1 is the schematic diagram of pulsed laser deposition (PLD) system.The mechanism of PLD method be at first with KrF excimer laser (excitation wavelength the is 248nm) scioptics of pulsewidth 25-30ns with about 10J/cm ²Energy density optically focused, the In in optical window shines vacuum plant ₂O ₃Target, behind the target absorbing laser, owing to Electron Excitation becomes high temperature fused state, material surface tens nanometer (nm) is evaporated, gasiform particulate is released and is diffused with column, on the suitable heated MgO single crystalline substrate of placing from the surperficial number centimeters of target, thereby adhere to, the accumulation deposit becomes In ₂O ₃Film.

Pulsed laser deposition of the present invention (PLD) technology prepares compound lining material MgIn ₂O ₄The concrete technology flow process of/MgO is as follows:

The MgO single crystalline substrate of＜1〉will polish, cleaning is sent into pulsed laser deposition PLD system and is prepared In ₂O ₃Film prepares In in the MgO single crystalline substrate ₂O ₃Film, the In more than 99.999% is adopted in the In source ₂O ₃Target.System adopts the KrF excimer laser of pulsewidth 25-30ns (nanosecond), and excitation wavelength is 248nm, and scioptics are with about 10J/cm ²Energy density optically focused, the In in optical window shines vacuum plant ₂O ₃Target, deposit In under the reaction atmosphere of oxygen enrichment ₂O ₃Film.

＜2〉then with the In that obtains in the upper step ₂O ₃/ MgO sample is put into annealing furnace, is warming up to 700～1500 ℃, in order to suppress In ₂O ₃Volatilization, adopt the reaction atmosphere of rich In, In ₂O ₃With MgO solid phase reaction taking place at high temperature, has obtained MgIn ₂O ₄Cover layer obtains having the MgIn of different-thickness by the control annealing time ₂O ₄Cover layer, thus MgIn obtained ₂O ₄/ MgO compound substrate.The compound substrate of this kind structure is suitable for epitaxial growth of high quality GaN.

Prepare MgIn with pulsed laser deposition shown in Figure 1 (PLD) experimental provision ₂O ₄The method of/MgO compound lining material, to be described as follows with preferred embodiment:

The MgO single crystalline substrate of polishing, cleaning is sent into pulsed laser deposition PLD system, prepare In in the MgO single crystalline substrate ₂O ₃Film, the In more than 99.999% is adopted in the In source ₂O ₃Target.System adopts the KrF excimer laser of pulsewidth 25-30ns (nanosecond), and excitation wavelength is 248nm, and scioptics are with about 10J/cm ²Energy density optically focused, the In in optical window shines vacuum plant ₂O ₃Target, deposit In under the reaction atmosphere of oxygen enrichment ₂O ₃Film, the temperature of MgO single crystalline substrate are 300 ℃, control In ₂O ₃The thickness of film is 500nm.Then with the In that obtains in the upper step ₂O ₃/ MgO sample is put into annealing furnace, is warming up to 1000 ℃, in order to suppress In ₂O ₃Volatilization, adopt the reaction atmosphere of rich In, In ₂O ₃With MgO solid phase reaction taking place at high temperature, has obtained MgIn ₂O ₄Cover layer obtains having the MgIn of different-thickness by the control annealing time ₂O ₄Cover layer recycles at last deionized water dissolving and falls responseless In ₂O ₃Layer, thus MgIn obtained ₂O ₄/ MgO compound substrate.The compound substrate of this kind structure is suitable for epitaxial growth of high quality GaN.

Claims (6)

1. A MgIn ₂ O ₄ /MgO composite substrate material, characterized in that a layer of MgIn ₂ O ₄ is provided on the MgO single crystal to form a MgIn ₂ O ₄ /MgO composite substrate. 2. The preparation method of MgIn ₂ O ₄ /MgO composite substrate material according to claim 1, characterized in that the In ₂ O ₃ thin film is prepared on the MgO single crystal substrate by pulsed laser deposition method, and then at high temperature, Through the solid-state reaction of _In2O3 and MgO, _{a MgIn2O4} capping layer _was formed on the MgO single crystal substrate. 3. The method for preparing the MgIn ₂ O ₄ /MgO composite substrate material according to claim 2, characterized in that the pulsed laser deposition method is to use a KrF excimer laser with a pulse width of 25-3Ons, through a lens with about The energy density of 10J/cm ² concentrates the light, and irradiates the In source in the vacuum device through the optical window. The In source is evaporated and vaporized, and the In ₂ O ₃ film is deposited on the heated MgO single crystal substrate. 4. The method for preparing MgIn ₂ O ₄ /MgO composite substrate material according to claim 2, characterized in that it comprises the following specific steps: <1> Preparation of In ₂ O ₃ thin films on MgO single crystal substrates: send the polished and cleaned MgO single crystal substrates into the pulsed laser deposition system, In source uses In ₂ O ₃ targets; pulse width 25 -30ns (nanosecond) KrF excimer laser, with a lasing wavelength of 248nm, condenses light through a lens with an energy density of about 10J/ ^cm2 , and irradiates the In ₂ O ₃ target in the vacuum device through the optical window. Deposit In ₂ O ₃ film on the heated MgO single crystal substrate under the reaction atmosphere of oxygen; <2> Solid-state reaction of In ₂ O ₃ and MgO: Put the obtained In ₂ O ₃ /MgO sample into an annealing furnace, raise the temperature to 700-1500°C, and make In ₂ O ₃ It reacts with MgO at high temperature in solid state to obtain a MgIn ₂ O ₄ covering layer and forms a MgIn ₂ O ₄ /MgO composite substrate material. 5. The method for preparing the MgIn ₂ O ₄ /MgO composite substrate material according to claim 2, characterized in that the purity of the In ₂ O ₃ target material is better than 99.999%. 6. The preparation method of MgIn ₂ O ₄ /MgO composite substrate material according to claim 2, characterized _{in that} the optimum temperature in the annealing furnace is 1000 ℃.