Stimulated emission in GaN thin films in the temperature range of 300-700 K

We report the results of an experimental study on stimulated and spontaneou s emission from high-quality single-crystal GaN films grown on 6H-SiC and ( 0001) sapphire substrates in the temperature range of 300-700 K. We observe d edge-emitted stimulated emission (SE) at temperatures as high as 700 K fo r samples grown on both SiC and sapphire substrates. The energy position of the SE and spontaneous emission peaks were shown to shift linearly to long er wavelengths with temperature and empirical expressions for the energy po sitions are given. We demonstrate that the energy separation between the sp ontaneous and SE peaks gradually increases from 90 meV at 300 K to 200 meV at 700 K indicating that an electron-hole plasma is responsible for the SE mechanism in this temperature range. The temperature sensitivity of the SE threshold for different samples was studied and the characteristic temperat ure was found to be 173 K in the temperature range of 300-700 K for one of the samples studied. We suggest that the unique properties of SE in GaN thi n films at high temperatures could potentially be utilized in optoelectroni c devices. (C) 1999 American Institute of Physics. [S0021-8979(99)03703-2].