Growth temperature dependence and Si-doping effect on vacancy-type defect structure in MBE-grown GaCrN films

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

In the MBE growth of the GaCrN dilute magnetic semiconductor films, low temperature (LT) growth is important in order to dope Cr atoms to high concentration. However, the problem with LT growth is the formation of lattice defects in the films. In this study, we have investigated growth temperature dependence and Si-doping effect on vacancy-type defect structure in MBE-grown GaCrN films probed by a slow positron beam. As a result, LT-grown undoped GaCrN film indicates a high value of positron annihilation parameter which implies the existence of vacancy-type defects. Furthermore, the positron annihilation parameter value was decreased by Si doping. First principle calculations of annihilation -ray spectra revealed that both of the detected defects from the undoped LT-GaCrN and from the Si-doped LT-GaCrN film were vacancy clusters (V-V) and VN-related defects, respectively.