Properties of Zn-doped GaN. I. Photoluminescence

Zinc in GaN forms an efficient radiative center emitting blue light at 2.86±0.02 eV and acts as a deep acceptor which can make the crystal insulating. A systematic variation of growth conditions shows that an optimization of the photoluminescence efficiency is possible. Under nonoptimal conditions, lower photon energy emission is obtained. A temperature-dependent competing nonradiative process has an activation energy of 0.33±0.15 eV. The emission peak exhibits a negligible spectral shift with temperature. The response time of the blue photoluminescence is several orders of magnitude slower than the near-gap transition. It is suggested that the photoluminescence is due to a radiative transition from the conduction band tail to the Zn acceptor levels.