Effects of V/III ratio on the growth of a-plane GaN films

• 作 者: 谢自力 李弋 刘斌 张荣 修向前 陈鹏 郑有炓
• 机 构: Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronics Science and Engi
• 出 处: Chinese Physics B
• 发表日期: 2011年10期
• 关键词: sapphire triangular roughness Atomic vapour FWHM polar MOCVD epitaxial rotation

The non-polar a-plane GaN is grown on an r-plane sapphire substrate directly without a buffer layer by metalorganic chemical vapour deposition and the effects of V/III ratio growth conditions are investigated. Atomic force microscopy results show that triangular pits are formed at a relatively high V/III ratio, while a relatively low V/III ratio can enhance the lateral growth rate along the c-axis direction. The higher V/III ratio leads to a high density of pits in comparison with the lower V/III ratio. The surface morphology is improved greatly by using a low V/III ratio of 500 and the roughness mean square of the surface is only 3.9 nm. The high resolution X-ray diffraction characterized crystal structural results show that the rocking curve full width at half maximum along the m axis decreases from 0.757 to 0.720 , while along the c axis increases from 0.220 to 0.251 with the V/III increasing from 500 μmol/min to 2000 μmol/min, which indicates that a relatively low V/III ratio is conducible to the c-axis growth of a-plane GaN.

The non-polar a-plane GaN is grown on an r-plane sapphire substrate directly without a buffer layer by metalorganic chemical vapor deposition and the effects of V / III ratio growth conditions are investigated. Atomic force microscopy results show that triangular pits are formed at a relatively high V / III ratio, while a relatively low V / III ratio can enhance the lateral growth rate along the c-axis direction. The higher V / III ratio leads to a high density of pits in comparison with the lower V / III ratio. The surface morphology is improved greatly by using a low V / III ratio of 500 and the roughness mean square of the surface is only 3.9 nm. The high resolution X-ray diffraction characterized crystal structure show that the rocking curve full width at half maximum along the m axis decreases from 0.757 to 0.720, while along the c axis increases from 0.220 to 0.251 with the V / III increasing from 500 μmol / min to 2000 μmol / min, which indicates that a relatively low V / III ratio is conducible to the c-axis growth of a-plane GaN.