As-grown deep-level defects in n-GaN grown by metal-organic chemical vapor deposition on freestanding GaN

作者：Chen Shang^*; Honda Unhi; Shibata Tatsunari; Matsumura Toshiya; Tokuda Yutaka; Ishikawa Kenji; Hori Masaru; Ueda Hiroyuki; Uesugi Tsutomu; Kachi Tetsu

来源：Journal of Applied Physics, 2012, 112(5): 053513.

DOI：10.1063/1.4748170

Traps of energy levels E-c -0.26 and E-c -0.61 eV have been identified as as-grown traps in n-GaN grown by metal-organic chemical vapor deposition by using deep level transient spectroscopy of the Schottky contacts fabricated by resistive evaporation. The additional traps of E-c -0.13 and E-c -0.65 eV have been observed in samples whose contacts are deposited by electron-beam evaporation. An increase in concentration of the E-c -0.13 and E-c -0.65 eV traps when approaching the interface between the contact and the GaN film supports our argument that these traps are induced by electron-beam irradiation. Conversely, the depth profiles of as-grown traps show different profiles between several samples with increased or uniform distribution in the near surface below 50 nm. Similar profiles are observed in GaN grown on a sapphire substrate. We conclude that the growth process causes these large concentrations of as-grown traps in the near-surface region. It is speculated that the finishing step in the growth process should be an essential issue in the investigation of the surface state of GaN.

• 出版日期2012-9-1