Author/Authors :
Edwards، نويسنده , , N.V and Yoo، نويسنده , , S.D and Bremser، نويسنده , , M.D and Zheleva، نويسنده , , Ts and Horton، نويسنده , , M.N and Perkins، نويسنده , , N.R and Weeks Jr، نويسنده , , T.W. and Liu، نويسنده , , H and Stall، نويسنده , , R.A and Kuech، نويسنده , , T.F and Davis، نويسنده , , R.F and Aspnes، نويسنده , , D.E، نويسنده ,
Abstract :
We report spectroscopic ellipsometry (SE) and low-temperature reflectance data on epitaxial GaN thin film samples covering the widest range of tensile and compressive stress (−3.8–3.5 kbar) thus far. SE allows us to assess the preparation of smooth and abrupt GaN surfaces by chemical treatments in real time, and, coupled with the reflectance data, the E dn/dE contribution to dispersion, which is important for laser action. The reflectance data explicitly show the nonlinear behavior of the B–A and C–A splittings versus the energy of the A exciton. Lineshape ambiguities that hindered previous interpretations have been resolved with reciprocal space analysis, allowing us to obtain band parameters such as ΔSO=17.0±1 meV and ΔCF=9.8±1 meV with increased confidence.
