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The chemical, structural, electrical and optical properties of gallium nitride

wallpapers Tech 2021-04-08
Overview of Gallium Nitride
Gallium nitride is a very stable compound and a hard high melting point material with a melting point of about 1700°C. GaN has a high degree of ionization, which is the highest (0.5 or 0.43) among III-V compounds. Under atmospheric pressure, GaN crystals generally have a hexagonal wurtzite structure. It has 4 atoms in a cell, and the atomic volume is about half of GaAs. Because of its high hardness, it is also a good coating protection material.
 
Chemical properties
At room temperature, gallium nitride is insoluble in water, acid and alkali, but dissolves at a very slow rate in a hot alkali solution. NaOH, H2SO4, and H3PO4 can corrode poor-quality GaN relatively quickly, and can be used for defect detection of these low-quality GaN crystals. GaN exhibits unstable characteristics at high temperatures under HCL or H2 gas, and is most stable under N2 gas.
 
Structural characteristics
There are two main crystal structures of GaN, namely wurtzite structure and sphalerite structure.
 
Electrical characteristics
The electrical characteristics of GaN are the main factors affecting the device. Unintentionally doped GaN is n-type in all cases, and the electron concentration of the best sample is about 4×1016/cm3. In general, the prepared P-type samples are highly compensated.
Many research groups have been engaged in this area of research. Among them, Nakamura reported that the highest GaN mobility data is μn=600cm2/v·s and μn=1500cm2/v·s at room temperature and liquid nitrogen temperature, respectively, and the corresponding current-carrying The sub-concentrations are n=4×1016/cm3 and n=8×1015/cm3. The electron concentration values of the MOCVD deposited GaN layer reported in recent years are 4×1016/cm3, <1016/cm3; the result of plasma-activated MBE is 8×103/cm3, <1017/cm3.
 
Optical properties
The characteristics of GaN that people pay attention to are aimed at its application in blue and violet light-emitting devices. Maruska and Tietjen first accurately measured the direct gap energy of GaN as 3.39 eV. Several groups have studied the dependence of the GaN bandgap on temperature. Pankove et al. estimated an empirical formula for the temperature coefficient of the bandgap: dE/dT = -6.0×10-4eV/k. Monemar measured the basic bandgap as 3.503eV±0.0005eV, Eg=3.503+(5.08×10-4T2)/(T-996) eV at 1.6kT.

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Tag: Gallium   powder,GaN