氮化铝宽带隙半导体及其特性

Abstract.

Aluminum nitride is wide and direct band gap compound semiconductor material. High  temperature strength, good thermal conductivity, small thermal expansion coefficient, strong  corrosion resistance, good dielectric properties and other characteristics make aluminum nitride as  impact resistance material, crucible materials, and conductive materials widely applied in various  fields. This paper reviews the production method of aluminum nitride powder and its application in  different fields.

Introduction 

Aluminum nitride is a ceramic insulator, a third-generation semiconductor material. Aluminum  nitride in the band gap at room temperature is 6.42eV, thermal expansion coefficient of 4.5 ×  10-6°C; the maximum stable to 2200 °C [1-4].This paper describes the basic characteristics of  aluminum nitride based on aluminum nitride powder production method and its application in  various fields.

Basic Structure and Properties of Aluminum Nitride 

Comparisons of aluminum nitride and other materials are shown in Table 1. Compared with other  materials, it can be seen that the melting point of aluminum nitride is higher, the coefficient of  thermal conductivity is larger and the band gap is wider. These characteristics are caused by the  internal structure of the special aluminum nitride.

Aluminum nitride is connected by covalent bonds. Fig. 1 shows the crystal structure of  aluminum nitride. It has a hexagonal crystal structure, which is the same as zinc sulfide and zinc  sulfide ore. Aluminum nitride space group is P63mc [5]. Its spatial structure led aluminum nitride  has a high thermal stability, so that it should take before pressing and welding to produce  industrial-grade material.

Band-gap at room temperature of aluminum nitride is 6.42eV, which belongs to direct band-gap  semiconductor [6].The minimum value of its valence band and the maximum of its conduction band  are located on the origin of the K space, when the electron from the valence band to the conduction  band, only need to change the energy on, without changing the electron quasi-momentum, which  leads to the efficient transport of electrons, making aluminum nitride for light-emitting devices or  other optoelectronic devices.

Preparation Method of Aluminum Nitride  

Since aluminum nitride has good physical and chemical properties, it has been widely favored by  science, but because of its higher processing costs, method of manufacturing aluminum nitride will  also continue to develop.

Electrical Explosion Method. 

Electrical explosion method is able to extract high-purity  aluminum nitride methods emerged in recent years [10].Studies have shown that, under 34KV  power supply voltage and capacitance of 1.6μF storage conditions, high purity nitrogen as working  gas, the pressure in the product range of 0.25 ~ 1.50Mpa prepared for nano-aluminum nitride and  nano-aluminum mixtures.

Application of Aluminum Nitride 

Aluminum nitride has a wide band-gap width, the stable crystal structure, good dielectric  characteristics and the like so that it has been widely used.High purity aluminum nitride powder is  the main raw material to manufacture high thermal conductivity of the aluminum nitride ceramic  substrate.

The aluminum nitride ceramic substrate, high thermal conductivity, low coefficient of expansion,  high strength, high temperature, chemical resistance, high resistivity, low dielectric loss, is the ideal  LSI heat dissipation board and packaging materials[11].Aluminum nitride has high hardness  characteristics, is the new wear-resistant ceramic material that can be used badly worn parts  [12].The use of aluminum nitride ceramic heat melt erosion resistance and thermal shock resistance  can be made GaAs crystal crucible, aluminum evaporating dish, MHD power generation equipment  corrosion and high temperature turbine components [13].Use of its optical properties can be used  for infrared window. Aluminum nitride film can be made high-frequency piezoelectric elements,  VLSI substrate or the like.Aluminum nitride is non-toxic, better performance of its metalized  ceramic can replace toxic oxidation-sensitive porcelain is widely used in the electronics industry.

Fig1

In the preparation of high purity alumina. Due to the manufacturing process constraints, difficult  to synthesize short growth cycle, high-precision, low-cost, large-scale aluminum nitride powder.  This makes the price of aluminum nitride bottleneck expensive, even in its application to study  more, but limits the processing of large-scale use of aluminum nitride. Synthesis of superior quality  silicon nitride will be a trend of the future direction of technology development.

The oxidation of aluminum nitride.Exposed to the air increases the oxygen content of aluminum  nitride, it is necessary when producing aluminum nitride powder and then its surface modification.

We need to seize the pulse of the times, through scientific and technological progress and  constantly improve the processing technology of aluminum nitride, aluminum nitride expand the  application level.