Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 45: Group-III-Nitrides: Optical Properties II

HL 45.4: Talk

Wednesday, March 24, 2010, 15:15–15:30, H15

Excitonic dielectric function of hexagonal GaN — •Steve Lenk and Erich Runge — Institut für Physik und Institut für Mikro- und Nanotechnologien, Technische Universität Ilmenau, 98693 Ilmenau, Germany

We calculate the dielectric function of hexagonal GaN including the A-, B-, and C-excitons using a multi-valence band formalism. The importance of excitons for the interpretation of reflectance 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 structures of several parametrizations. We present the complex dielectric function as well as the deduced reflectivity spectra of the excitons in GaN. These results show qualitative and quantitative agreement 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).