Study Of Doped GaN Nanocrystals With Electron Microscopy And First-principles Theory

Gallium nitride?GaN?material with excellent physical,chemical,optical and electrical properties become the common materials in the fields of microelectronics and optoelectronics devices.Diffusion can change the microstructure of matrix,to improve the electrical,optical,thermal,magnetic and other properties of materials.This article mainly studied the electronic structure of Zn-doped GaN prepared by chemical vapor deposition?CVD?and Ce-doped GaN prepared by solid-state sintering treatment,the main contents are as follows:Firstly,the microstructure of GaN nano-materials was studied by transmission electron microscopy?TEM?which including contrast imaging technique,x-ray energy dispersive spectrometer?EDS?,high resolution transmission electron microscopy?HRTEM?,selected area electron diffraction?SAED?and other techniques.By associating low energy electron energy loss spectroscopy?EELS?with partial density of state?PDOS?which based upon the density function theory?DFT?,we studied the interband transition of the sample The results show that N 2p and outerelectrons of Ga influence the energy states near Fermi level.The dominant peak of GaN detected in experiments at about 19.3 eV.Secondly,the microstructure's differences between Zn-doped GaN and GaN were investigated by transmission electron microscopy and first-principles calculation method.Zn²⁺produces nitride vacancy,and it's also an indirect band gap semiconductor.On the top of valence band,Zn 3d affects hybrid orbitals,and the Fermi surface move to valence band,the band become split,so it's easy to form short-wavelength luminescent centre.Thirdly,a special architecture of GaN:Ce nano-material was investigated by TEM.Preferred orientation growth of GaN nanowire is[0001],with the increasing of sintering time,the lattice released strain and dislocations within the stacking fault image were also observed.The nanorods appear as zigzag shapes and growth along the same side.The angle of the end surface is 117^o.EELS result reflects the change of the sample's microstructure.