Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 31: Poster II

HL 31.3: Poster

Tuesday, February 26, 2008, 16:30–19:00, Poster D

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

We calculate the bandstructure near the Γ-point of A-, B-, and C-excitons in hexagonal GaN in the presence of an external electric field. The parametrization of Chuang and Chang [1] is used. The importance of excitons for the interpretation of electroreflectance spectroscopy was emphasized by several experimental groups, but only recently theoretical calculations were presented [2]. We derive the imaginary part of the dielectric function from a numerical solution of the excitonic Schrœdinger equation in a finite field, taking into account the full 6x6 valence band structure. Via Kramers-Kronig-Relation the real part of the dielectric function is evaluated. The derivative of the dielectric function yields the ER spectra. In particular, we compare the theoretical field-dependent oscillator strengths with experimental data.

[1]

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

[2]

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