Quantitative study for surface properties of AlGaN epi-layers by ARXPS

Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, 210096 Nanjing, P.R. China

^a e-mail: xzhang62@aliyun.com

Received: 12 August 2015
Revised: 8 September 2015
Accepted: 18 September 2015
Published online: 30 October 2015

Abstract

The surface chemical properties of Al_xGa_1-xN (x=0.35, 0.47, 0.60) epi-layers grown on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD) were quantitatively characterized by angle-resolved X-ray photoelectron spectroscopy (ARXPS). The results suggested that the Ga Auger peak for the Al_xGa_1-xN epi-layers was greatly suppressed with increasing Al composition since the amount of N-Ga bonds were dramatically decreased. Moreover, more Al-O bonds were found near the surfaces of the Al_xGa_1-xN epi-layers with relatively high Al composition due to the large chemical affinity of aluminum to oxygen. In addition, the Al composition in the Al_xGa_1-xN epi-layers was showed to be non-uniform because Al atom has higher oxidizability and lower mobility than Ga atom, especially for the Al_xGa_1-xN epi-layers with relatively high Al composition. Our work should be very helpful to further investigation of the surface properties for making Al-containing III-nitrides optoelectronic devices.