GaN layers with different polarities prepared by radio frequency molecular beam epitaxy and characterized by Raman scattering
Zhong Fei(钟飞)†, Li Xin-Hua(李新化), Qiu Kai(邱凯), Yin Zhi-Jun(尹志军), Ji Chang-Jian(姬长建), Cao Xian-Cun(曹先存), Han Qi-Feng(韩奇峰), Chen Jia-Rong(陈家荣), and Wang Yu-Qi(王玉琦)
Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Abstract GaN layers with different polarities have been prepared by radio-frequency molecular beam epitaxy (RF-MBE) and characterized by Raman scattering. Polarity control are realized by controlling Al/N flux ratio during high temperature AlN buffer growth. The Raman results illustrate that the N-polarity GaN films have frequency shifts at $A_{1}$(LO) mode because of their high carrier density; the forbidden $A_{1}$(TO) mode occurs for mixed-polarity GaN films due to the destroyed translation symmetry by inversion domain boundaries (IDBS); Raman spectra for Ga-polarity GaN films show that they have neither frequency shifts mode nor forbidden mode. These results indicate that Ga-polarity GaN films have a better quality, and they are in good agreement with the results obtained from the room temperature Hall mobility. The best values of Ga-polarity GaN films are 1042 cm$^{2}$/Vs with a carrier density of 1.0$\times $10$^{17}$ cm$^{ - 3}$.
Received: 11 December 2006
Revised: 15 February 2007
Accepted manuscript online:
PACS:
81.15.Hi
(Molecular, atomic, ion, and chemical beam epitaxy)
Fund: Project supported by the
National Natural Science Foundation of China (Grant No 10574130).
Cite this article:
Zhong Fei(钟飞), Li Xin-Hua(李新化), Qiu Kai(邱凯), Yin Zhi-Jun(尹志军), Ji Chang-Jian(姬长建), Cao Xian-Cun(曹先存), Han Qi-Feng(韩奇峰), Chen Jia-Rong(陈家荣), and Wang Yu-Qi(王玉琦) GaN layers with different polarities prepared by radio frequency molecular beam epitaxy and characterized by Raman scattering 2007 Chinese Physics 16 2786
Altmetric calculates a score based on the online attention an article receives. Each coloured thread in the circle represents a different type of online attention. The number in the centre is the Altmetric score. Social media and mainstream news media are the main sources that calculate the score. Reference managers such as Mendeley are also tracked but do not contribute to the score. Older articles often score higher because they have had more time to get noticed. To account for this, Altmetric has included the context data for other articles of a similar age.