1. Contactless electroreflectance, in the range of 20 K<T<300 K, of freestanding wurtzite GaN prepared by hydride-vapor-phase epitaxy.
- Author
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Huang, Y. S., Pollak, Fred H., Park, S. S., Lee, K. Y., and Morkoç, H.
- Subjects
GALLIUM ,NITROGEN ,EPITAXY ,TEMPERATURE - Abstract
We have performed a detailed contactless electroreflectance study of the interband excitonic transitions on both the Ga and N faces of a 200-μm-thick freestanding hydride-vapor-phase-epitaxy grown wurtzite GaN sample with low defect concentration in the temperature range between 20 and 300 K. The transition energies of the A, B, and C excitons and broadening parameters of the A and B excitons have been determined by least-square fits to the first derivative of a Lorentzian line shape. The energy positions and separations of the excitonic transitions in the sample reveal the existence of residual strain. At 20 K the broadening parameter of A exciton deduced for the Ga (5×10[SUP5] dislocation cm[SUP-2] and N (1×10[SUP7] dislocation cm[SUP-2]) faces are 3 and 7 meV, respectively, indicating a lower defect concentration on the former face. The parameters that describe the temperature dependence of the interband transition energies of the A, B, and C excitons as well as the broadening function of the A and B features are evaluated. The results from an analysis of the temperature dependence of the broadening function of excitons A and B indicate that GaN exhibits a very large exciton-phonon coupling. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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