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HL: Fachverband Halbleiterphysik

HL 13: Optical properties

HL 13.3: Vortrag

Dienstag, 24. März 2009, 10:00–10:15, BEY 118

Excitonic electroreflectance spectra of hexagonal GaN — •Steve Lenk and Erich Runge — Institut für Physik, Technische Universität Ilmenau, Germany

We calculate the dielectric function including the A-, B-, and C-excitons of hexagonal GaN in the presence of an external electric field by using a multi-valence band formalism. The importance of excitons for the interpretation of electroreflectance spectroscopy of GaN was emphasized by several experimental groups, but only recently theoretical calculations were presented [1]. We derive the dielectric function from a numerical solution of an initial value problem [2] via an exponential split-operator method, taking into account the full 6x6 valence band structure of Chuang and Chang [3]. We present the complex dielectric function as well as the deduced reflectivity and absorption spectra of the excitons in GaN. These and the electroreflectance spectra are compared with recent experimental studies.

[1]

A.T. Winzer, G. Gobsch, and R. Goldhahn, Phys. Rev. B 74, 125207 (2006).

[2]

S. Glutsch, Excitons in Low−Dimensional Semiconductors, Springer Heidelberg (2004).

[3]

S.L. Chuang and C.S. Chang, Phys. Rev. B 54, 2491 (1996).