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Your search keyword '"Zhang, Guo"' showing total 4 results
Start Over Author "Zhang, Guo" Topic microstructure Publisher iop publishing
4 results on '"Zhang, Guo"'

1. Effect of annealing on photoluminescence and microstructures of InGaN/GaN multi-quantum well with Mg-doped p-type GaN

Author

Yang Zhi-Jian, Feng Yu-Chun, Yu Tong-Jun, Niu Hanben, Li Zhong-Hui, Guo Bao-ping, and Zhang Guo-Yi

Subjects
Photoluminescence, Materials science, business.industry, Annealing (metallurgy), Doping, General Physics and Astronomy, Microstructure, Quantum size effect, symbols.namesake, Stark effect, symbols, Optoelectronics, Metalorganic vapour phase epitaxy, business, Quantum well
Abstract

InGaN/GaN multi-quantum well structure with Mg-doped p-type GaN was grown by low-pressure metalorganic vapour phase epitaxy. After rapid-thermal-annealing at 700 and 900 degrees C, both the red-shift and the blue-shift of the photoluminescence (PL) peak, the decreased and the enhancement of the PL intensity were observed. The transmission electron microscopic images showed that InGaN multi-quantum-dots-like (MQD-like) structures with dimensions less than 5×10nm were formed in InGaN wells. The changes of PL spectra could be tentatively attributed to the competition between the red-shift mechanism of the quantum-confined Stark effect and the blue-shift mechanism of the quantum size effect due to MQD-like structures.

Published
2005

2. Microstructures of GaN Films Laterally Overgrown on Si(111) by Hydride Vapour Phase Epitaxy

Author

Zhang Rong, Gu Shulin, L. F. Kuech, Wang Feng, LI Zhi-Feng, Zhu Jian-Min, Zheng Youdou, Chen Zhizhong, Shen Bo, Zhang Guo-Yi, and Qin Zhi-Xin

Subjects
Optics, Materials science, business.industry, Etching (microfabrication), Hydride vapour phase epitaxy, Perpendicular, General Physics and Astronomy, Optoelectronics, Dislocation, Microstructure, Epitaxy, business, Spectral line
Abstract

We have investigated the microstructures of GaN films laterally epitaxially overgrown (LEO) on Si(111) substrates using hydride vapour phase epitaxy. The threading dislocation density in the LEO GaN is reduced by about two orders. Different etching angles of the two sidewalls of SiO2 masks (66o and 90o) lead to the asymmetry of the LEO and cause the particular microstructures of LEO GaN. In micro-Raman spectra, the intensities vary weakly periodically about 5 µm perpendicular to the mask stripes. The indistinct selective growth in the top surface is discussed.

Published
2002

3. Effect of pulsed bias on the properties of ZrN/TiZrN films deposited by a cathodic vacuum arc.

Author

Zhang Guo-Ping, Wang Xing-Quan, Lu Guo-Hua, Zhou Lan, Huang Jun, Chen Wei, and Yang Si-Ze

Subjects
*MULTILAYERS, *ZIRCONIUM compounds, *TITANIUM compounds, *ION bombardment, *MICROSTRUCTURE, *HARDNESS, *ADHESION
Abstract

ZrN/TiZrN multilayers are deposited by using the cathodic vacuum arc method with different substrate bias (from 0 to -800 V), using Ti and Zr plasma flows in residual N2 atmosphere, combined with ion bombardment of sample surfaces. The effect of pulsed bias on the structure and properties of films is investigated. Microstructure of the coating is analyzed by X-ray diffraction (XRD), and scanning electron microscopy (SEM). In addition, nanohardness, Young's modulus, and scratch tests are performed. The experimental results show that the films exhibit a nanoscale multilayer structure consisting of TiZrN and ZrN phases. Solid solutions are formed for component TiZrN films. The dominant preferred orientation of TiZrN films is (111) and (220). At a pulsed bias of -200 V, the nanohardness and the adhesion strength of the ZrN/TiZrN multilayer reach a maximum of 38 GPa, and 78 N, respectively. The ZrN/TiZrN multilayer demonstrates an enhanced nanohardness compared with binary TiN and ZrN films deposited under equivalent conditions. [ABSTRACT FROM AUTHOR]

Published
2013
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4. Investigation of the Cr:LiSrAlF6 crystal by high-temperature Raman spectroscopy.

Author

Wang Di, Wan Song, Zhang Qing, Sun Dun, Gu Gui, Yin Shao, Zhang Guo, You Jing, Lin and, and Wang Yuan

Subjects
LITHIUM compounds, HIGH temperatures, RAMAN spectroscopy, MELTING points, MICROSTRUCTURE, FLUORIDES
Abstract

In this paper, Cr-doped LiSrAlF6 crystals are investigated using high-temperature Raman spectroscopy and the single-crystal Raman spectra of Cr:LiSrAlF6 are analysed by factor group theory and comparison with other fluorides. The results indicate that Cr:LiSrAlF6 is stable below its melting point; Raman peaks located at 561, 322 and 250 cm[?]1 are assigned to the A1g modes of AlF6, SrF6 and LiF6 octachdra, respectively; with temperature increasing, Raman peaks associated with AlF6 octahedra shift towards low frequencies, while LiF6 and SrF6 octahedra are temperature-insensitive; around the crystal melting point, three new Raman peaks occur, which are associated with the AlF6 octahedral chain structure. Finally, the microstructural evolution of Cr:LiSrAlF6 from room temperature to its melting point is discussed based on its Raman spectra. [ABSTRACT FROM AUTHOR]

Published
2011
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