Positron annihilation in irradiation-induced defects in GaN

Yabuuchi, Atsushi; Maekawa, Masaki; Kawasuso, Atsuo; Hasegawa, Shigehiko*; Zhou, Y.-K.*; Asahi, Hajime*

The Doppler broadening of the positron annihilation radiation of the electron irradiated GaN sample was measured. The purpose of this study was to clarify the positron annihilation characteristics at point defects in GaN. 2 MeV electrons were irradiated to the MOCVD-GaN (2 m)/Sapphire substrate with a total fluence of 6.510 e/cm at 60 C. The irradiated GaN was measured by using slow positron beam. As a result, the observed spectrum showed the existence of not monovacancies but vacancy clusters. This means vacancy clusters existed intrinsically in MOCVD-GaN film.