Zhigang Jia
Taiyuan University of Technology
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Featured researches published by Zhigang Jia.
RSC Advances | 2015
Lin Shang; Taiping Lu; Guangmei Zhai; Zhigang Jia; Hua Zhang; Shufang Ma; Tianbao Li; Jian Liang; Xuguang Liu; Bingshe Xu
The role of the nucleation layer thickness on the GaN crystal quality grown by metal organic chemical vapor deposition is explored. The surface morphologies of a low-temperature GaN nucleation layer (NL) investigated by Atomic Force Microscopy shows the nuclei grain size increases with increasing thickness. After annealing, island-like morphologies of the low-temperature GaN NL are obtained. Increasing the NL thickness is beneficial for obtaining larger island size, however, the uniformity of the island size is deteriorated. The high-resolution X-ray diffraction analysis reveals that bulk GaN crystal properties are closely connected with NL thickness, which can be well explained by the dislocation generation and propagation process in the GaN films. All the obtained results indicate that the NL thickness effectively controls the size and density of the islands and thus determines the crystal properties of GaN films.
Nanoscale Research Letters | 2017
Xiaorun Zhou; Taiping Lu; Yadan Zhu; Guangzhou Zhao; Hailiang Dong; Zhigang Jia; Yongzhen Yang; Yongkang Chen; Bingshe Xu
Surface morphology evolution mechanisms of InGaN/GaN multiple quantum wells (MQWs) during GaN barrier growth with different hydrogen (H2) percentages have been systematically studied. Ga surface-diffusion rate, stress relaxation, and H2 etching effect are found to be the main affecting factors of the surface evolution. As the percentage of H2 increases from 0 to 6.25%, Ga surface-diffusion rate and the etch effect are gradually enhanced, which is beneficial to obtaining a smooth surface with low pits density. As the H2 proportion further increases, stress relaxation and H2 over- etching effect begin to be the dominant factors, which degrade surface quality. Furthermore, the effects of surface evolution on the interface and optical properties of InGaN/GaN MQWs are also profoundly discussed. The comprehensive study on the surface evolution mechanisms herein provides both technical and theoretical support for the fabrication of high-quality InGaN/GaN heterostructures.
Nanoscale Research Letters | 2018
Tianbao Li; Chenyang Liu; Zhe Zhang; Bin Yu; Hailiang Dong; Wei Jia; Zhigang Jia; Chunyan Yu; Lin Gan; Bingshe Xu; Haiwei Jiang
The growth mechanism of GaN epitaxial layers on mechanically exfoliated graphite is explained in detail based on classic nucleation theory. The number of defects on the graphite surface can be increased via O-plasma treatment, leading to increased nucleation density on the graphite surface. The addition of elemental Al can effectively improve the nucleation rate, which can promote the formation of dense nucleation layers and the lateral growth of GaN epitaxial layers. The surface morphologies of the nucleation layers, annealed layers and epitaxial layers were characterized by field-emission scanning electron microscopy, where the evolution of the surface morphology coincided with a 3D-to-2D growth mechanism. High-resolution transmission electron microscopy was used to characterize the microstructure of GaN. Fast Fourier transform diffraction patterns showed that cubic phase (zinc-blend structure) GaN grains were obtained using conventional GaN nucleation layers, while the hexagonal phase (wurtzite structure) GaN films were formed using AlGaN nucleation layers. Our work opens new avenues for using highly oriented pyrolytic graphite as a substrate to fabricate transferable optoelectronic devices.
AIP Advances | 2018
Tianbao Li; Chenyang Liu; Zhe Zhang; Bin Yu; Hailiang Dong; Wei Jia; Zhigang Jia; Chunyan Yu; Lin Gan; Bingshe Xu
In this study, GaN epitaxial layers were successfully deposited on a multilayer graphene (MLG) by using metal-organic chemical vapor deposition (MOCVD). Highly crystalline orientations of the GaN films were confirmed through electron backscatter diffraction (EBSD). An epitaxial relationship between GaN films and MLG is unambiguously established by transmission electron microscope (TEM) analysis. The Raman spectra was used to analyze the internal stress of GaN films, and the spectrum shows residual tensile stress in the GaN films. Moreover, the results of the TEM analysis and Raman spectra indicate that the high quality of the MLG substrate is maintained even after the growth of the GaN film. This high-quality MLG makes it possible to easily remove epitaxial layers from the supporting substrate by micro-mechanical exfoliation technology. This work can aid in the development of transferable devices using GaN films.
Optical Materials Express | 2017
Dan Han; Shufang Ma; Zhigang Jia; Peizhi Liu; Wei Jia; Hailiang Dong; Lin Shang; Guangmei Zhai; Bingshe Xu
A InGaN/GaN micro-square array light-emitting diode (LED) chip (micro-chip) has been successfully fabricated by the focused ion beam (FIB) etching technique, which can reduce ohmic contact degradation in the fabrication process of three-dimensional (3D) structure devices. Our results show that the micro-chip exhibits a similar current–voltage performance compared to the corresponding InGaN/GaN planar LED chip (planar-chip). At the driving current of 20 mA, the output power of the micro-chip is improved by 17.8% in comparison to that of the planar-chip. A relatively broad emission and enhanced emission intensity in the perpendicular direction are obtained in angular-resolved EL (AREL) measurements for the micro-chip. Three-dimensional finite difference time domain (FDTD) simulations have also proven enhanced emitted optical energy distribution. The enhancement mechanism is correlated to the increased light extraction efficiency (LEE) of the micro-chip, mainly owing to more photons from the exposed MQWs surfaces that can be efficiently extracted by the micro-square array.
Nanoscale Research Letters | 2017
Yadan Zhu; Taiping Lu; Xiaorun Zhou; Guangzhou Zhao; Hailiang Dong; Zhigang Jia; Xuguang Liu; Bingshe Xu
Physical Chemistry Chemical Physics | 2016
Hailiang Dong; Jing Sun; Shufang Ma; Jian Liang; Taiping Lu; Zhigang Jia; Xuguang Liu; Bingshe Xu
Superlattices and Microstructures | 2017
Jianjie Liu; Zhigang Jia; Shufang Ma; Hailiang Dong; Guangmei Zhai; Bingshe Xu
Materials Letters | 2018
Guangyun Tong; Wei Jia; Teng Fan; Hailiang Dong; Tianbao Li; Zhigang Jia; Bingshe Xu
Superlattices and Microstructures | 2017
Yadan Zhu; Taiping Lu; Xiaorun Zhou; Guangzhou Zhao; Hailiang Dong; Zhigang Jia; Xuguang Liu; Bingshe Xu