GaN layers with different polarities prepared by radio frequency molecular beam epitaxy and characterized by Raman scattering

• 来源期刊: 中国物理（英文版）
• 关键词: polarity gallium nitride Raman scattering
• 年，卷（期）: 2007,（9）
• 页码范围: 2786-2790
• 页数: 5页
• 语种: 英文

摘要

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 A1(LO) mode because of their high carrier density; the forbidden A1 (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 cm2/Vs with a carrier density of 1.0×1017 cm-3.