Optical spectroscopy of Si-related donor and acceptor levels in Si-doped GaN grown by hydride vapor phase epitaxy

The optical properties of n-type GaN grown by hydride vapor phase epitaxy,w ith intentional Si doping levels ranging from nominally undoped to N-D - N- A = 4 x 10(17) cm(-3), are investigated using low temperature photoluminesc ence. We identify free and neutral donor-bound exciton transitions and two- electron satellites (TES) at 1.7 K. The energy difference between the princ ipal neutral donor-bound exciton peak and its TES yields a Si donor,binding energy of 22 meV. The intensity of the Si-related TES increases with incre asing Si concentration. The Si donor is much shallower than the two residua l donors, which have binding energies of 28 and 34 meV. This result suggest s that the main residual donors in this material land possibly in many laye rs grown by metal organic chemical vapor deposition and metal organic molec ular beam epitaxy as well) are not Si. Silicon doping also introduces an ac ceptor level with a binding energy of about 224 meV. (C) 1998 American Inst itute of Physics.