CN1622409A

CN1622409A - Zinc oxide bluish violet light semiconductor growth using liquid phase epitaxial method

Info

Publication number: CN1622409A
Application number: CN 200310115258
Authority: CN
Inventors: 涂朝阳; 吴柏昌; 李坚富; 朱昭捷; 王燕; 游振宇; 黄燕
Original assignee: Fujian Institute of Research on the Structure of Matter of CAS
Current assignee: Fujian Institute of Research on the Structure of Matter of CAS
Priority date: 2003-11-27
Filing date: 2003-11-27
Publication date: 2005-06-01
Anticipated expiration: 2023-11-27
Also published as: CN100401602C

Abstract

The present invention describes liquid phase epitaxial growth process of growing blue-purple light ZnO semiconductor. Five-valent P ion doped p-type ZnO semiconductor monocrystal is first grown in a molten salt process inside growth system with P2O5 flux; and trivalent Al ion doped n-type ZnO semiconductor monocrystal is then grown on the surface of the p-type ZnO semiconductor monocrystal via liquid phase epitaxial growth process in the growth system with Al2O3 flux. Through further crystal processing, blue-purple light ZnO semiconductor device with p-n juction is prepared. Thus produced blue-purple light ZnO semiconductor monocrystal has the advantages of less faults and high integrality, and the production process has simple growth equipment and low cost.

Description

Zinc oxide bluish violet light semiconductor grown by liquid phase epitaxial method

The invention relates to the field of crystal material preparation. In particular to a liquid phase epitaxial growth technology of ZnO bluish violet light semiconductor single crystal with low defect and high integrity.

Background art ZnO is a II-VI semiconductor,having a direct wide band gap, band gap E_g3.37ev, the exciton bonding energy is large, the value is 60ev, ultraviolet light can be generated, if an ultraviolet laser is made to replace a blue laser, the ultraviolet laser becomes a new generation Compact Disc (CD) reader, the CD disc groove can be smaller, the data storage capacity of the CD can be expanded by several times, and the ultraviolet laser is the focus of intense competition of scientists in various countries at present. Recently, the U.S. ballistic missile defense planning organization (BMDO) has invested one million dollars, letting Cermet corporation develop ZnO semiconductor technology. Mainly develops the p-n junction technology of ZnO semiconductor, and the implementation of the engineering mainly uses the ZnO bulk crystal growth technology, and of course, the thin film growth technology is also possible.

Although the energy gap of ZnO semiconductors is sufficiently large, attempts to fabricate lasers with this material have been largely unsuccessful. Although crystals can induce emission of photons of ultraviolet light, the emission is weak, mainly due to absorption of photons by defects in the crystal.

Therefore, in order to meet the application requirements, it is required to be able to grow ZnO crystals of large size and high quality in large quantities. Meanwhile, in order to form a p-n junction, the crystal needs to be doped with some required ions.

ZnO crystals are currently grown predominantly by hydrothermal methods (R.A.Laudise, E.D.Kolb, A.J.Caporoso, J.Am.Cream.Soc.47(1964) 9; T.Sekiguchi, S.Miyashita, K.Obara et al.J.CrystalGrowth 214/215(2000) 72;), vapor phase methods (D.C.Look, D.C.Reynolds, J.R.Sizelove et al.Solid State Commun.150(1998) 399;), slow cooling from the melt (J.W.Nielsen, E.F.Dearorn, J.Phys.Chem.64 (1961760) 2; B.M.Wanklyn, J.Crystan. 7(1970) 107). However, these methods can only grow crystals with smaller size, and are far from meeting the application requirements. ZnO is isocompositionally melted at 1975 ℃ but it is highly volatile at high temperatures, and thus cannot be applied to ZnO crystals as a Czochralski method for growing large-sized crystals. However, the growth by the molten salt method is not only cheap and simple in equipment, but also can grow large-size crystals, and can reduce the growth temperature and reduce the volatilization of ZnO, and meanwhile, a fluxing agent with proper components can be selected to enable the crystals to be doped with proper ions. Of course, a significant characteristic of the molten salt method is that the growth rate is slow, but the method is favorable for orderly arrangement of ions in the crystal and reduces the defect of position vacancy in the crystal. Based on the growth principle of a molten salt method, the ZnO bluish violet light semiconductor device with a complete p-n junction can be prepared by adopting a liquid phase epitaxial method for growth.

The invention aims to grow a ZnO bluish violet light semiconductor single crystal with low defect and high integrity by adopting a liquid phase epitaxy method. Based on the growth principle of molten salt method, P is selected respectively₂O₅And Al₂O₃A growth system of the fluxing agent adopts a liquid phase epitaxial method to splice and assemble ZnO-p and ZnO-n semiconductor single crystals to prepare a high-quality ZnObluish violet light semiconductor device with low defects, high integrity and complete p-n junctions.

The technical scheme for realizing the aim of the invention is as follows: firstly, P is selected to contain₂O₅A growth system of fluxing agent, which adopts a molten salt growth method to grow P-doped⁵⁺Ionic ZnO-p type semiconductor single crystal; then selecting Al-containing₂O₃A growth system of fluxing agent, adopting a liquid phase epitaxy method to grow Al-doped on the surface of a ZnO-p type semiconductor single crystal³⁺And cutting the crystal to make the ZnO-p type semiconductor single crystal and the ZnO-n type semiconductor single crystal at two ends of the p-n junction have the same size, and polishing the two end faces vertical to the p-n junction to prepare the ZnO blue-violet light semiconductor device with the p-n junction.

The growth process is as follows: weighing raw materials, grinding and uniformly mixing the raw materials by using an agate mortar, then putting the mixture into a platinum crucible with the diameter of 70mm multiplied by 70mm, keeping the temperature at 1100 ℃ for 24 hours, then cooling the mixture at a cooling rate of 5 ℃/d, treating the mixture by using deionized water when the growth is finished, and separating crystals. Then, the resulting crystal is used as a seed crystal to further grow a large crystal: measuring the saturation temperature of the melt by a seed crystal trial method after the raw materials are melted, putting the seed crystal into the melt at about 30 ℃ above the saturation temperature, reducing the melt to the saturation temperature after half an hour, starting to reduce the temperature at the speed of 2-3 ℃/d, controlling the rotation speed of the seed crystal to be 4.5-9rpm, lifting the crystal from the liquid level of the melt after the crystal grows for 15-20 days, then returning to the room temperature at the speed of 30 ℃/h,

Detailed Description

Directly using 34 mol% of P₂O₅As a flux. Firstly, the better seed crystal is spontaneously grown by adopting slow cooling, and then the P-doped seed crystal is grown by adopting a top seed crystal method⁵⁺Ionic ZnO-p type semiconductor single crystal. The raw materials are ZnO and NH with high purity (more than 4N)₄H₂PO₄In which NH₄H₂PO₄After heating, P will be formed₂O₅，

Namely:

weighing raw materials, grinding and uniformly mixing the raw materials by using an agate mortar, then putting the mixture into a platinum crucible with the diameter of 70mm multiplied by 70mm, keeping the temperature at 1100 ℃ for 24 hours, then cooling the mixture at a cooling rate of 5 ℃/d, treating the mixture by using deionized water when the growth is finished, and separating crystals. Then, the resulting crystal is used as a seed crystal to further grow a large crystal: after the raw materials are melted, measuring the saturation temperature of the melt by using a seed crystal trial method, putting the seed crystal into the melt at a temperature which is about 30 ℃ above the saturation temperature, reducing the melt to the saturation temperature after half an hour, starting to reduce the temperature at a speed of 3 ℃/d, wherein the rotation speed of the seed crystal is 9rpm, lifting the crystal from the liquid level of the melt after the crystal grows for 20 days, and then returning the crystal to the room temperature at a speed of 30 ℃/h to obtain the ZnO-p type semiconductor single crystal.

Then, the ZnO-p type semiconductor singlecrystal was oriented, the direction of one crystal principal axis was selected, optical polishing was conducted for use, and then 65 mol% of B was used₂O₃+10 mol% of Al₂O₃As a flux. The raw materials are high-purity (more than 4N) ZnO and Al₂O₃、H₃BO₃. Weighing raw materials, grinding with agate mortar, mixing, loading into platinum crucible of phi 70mm × 70mm, measuring the saturation temperature of the melt by seed crystal method, and processing ZnO-p type semiconductor single crystal at saturation temperatureThe surface is lowered into the melt, the temperature is reduced at the speed of 3 ℃/d, the rotation speed of the seed crystal is 8rpm, after the seed crystal grows for 20 days, the crystal is lifted from the liquid level of the melt, and then the temperature is reduced to the room temperature at the speed of 30 ℃/h. And cutting the crystal to ensure that the sizes of the ZnO-p type semiconductor single crystal and the ZnO-n type semiconductor single crystal at the two ends of the p-n junction are equal, and polishing the two end faces vertical to the p-n junction to prepare the ZnO blue-violet light semiconductor device with the p-n junction.

Claims

1. Growing a ZnO blue-violet light semiconductor by a liquid phase epitaxy method, wherein the method comprises three parts of growing a ZnO-n type semiconductor single crystal, growing a ZnO-p type semiconductor single crystal and processing the crystal, and is characterized in that:

(1) growing a ZnO-n type semiconductor single crystal by a molten salt growth method;

(2) growing a ZnO-p type semiconductor single crystal by adopting a liquid phase epitaxial method;

(3) and processing the crystal to ensure that the sizes of the ZnO-p type semiconductor single crystal and the ZnO-n type semiconductor single crystal at two ends of the p-n junction are equal, and polishing the two end faces vertical to the p-n junction to prepare the ZnO bluish violet light semiconductor device with the p-n junction.