Optical properties of bulk-like nitride semiconductors
Technische Universität Ilmenau, Institut für Physik, PF 100565, Ilmenau 98684, Germany
The first part of the talk provides an overview how to determine a reliable complex dielectric function (DF) of a material from spectroscopic ellipsometry studies covering the whole spectral range between infrared and vacuum-ultraviolet. Then, the peculiarities of the spectral dependence of the DF for nitride semiconductors with zinc-blende and wurtzite crystal structure will be discussed in detail. It is demonstrated that the inclusion of electron-hole interaction becomes very important for correlating the experimental results with one-electron band-structure calculations, i.e. for determining transition energies for critical points of the band structure. The valence-band ordering at the center of the Brillouin zone has a strong impact on the optical anisotropy of hexagonal compounds around the band gap. Recent results, obtained from measurements on non-polar surface orientations, demonstrate the main aspects. Many-particle effects such as band-gap renormalization and band-filling lead to an energy shift of the absorption edge for high carrier concentrations. Examples for the DF analysis under those conditions will be presented in the final part.
Presentation: Keynote lecture at E-MRS Fall Meeting 2009, Symposium A, by Ruediger Goldhahn
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-07-23 15:52 Revised: 2009-07-23 15:52