Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 43: Symposium Nitride

HL 43.4: Vortrag

Donnerstag, 27. März 2003, 16:00–16:30, POT/81

InN and InGaN: Materials for IR applications? — •Friedhelm Bechstedt — Friedrich-Schiller-Universität, Institut für Festkörpertheorie und Theoretische Optik, Max-Wien-Platz 1, 07743 Jena

Among the group-III nitrides, InN remains the most mysterious compound, due mainly to difficulties in growing high-quality crystals or crystalline layers. A typical issue is the fundamental energy gap E_g. Based on the quasiparticle theory, in this talk arguments are given, why E_g should be smaller than 1 eV, in contrast to the value of about 2 eV recently believed. The careful discussion includes the role of the strong pd repulsion and the influence of the crystal structure. The confirmation of the prediction of a small gap of 0.8 eV or even less by recent absorption, photoluminescence and photoluminescence excitation spectroscopy measurements of MBE and MOCVD samples is demonstrated. The novel “small-gap” InN is characterized by a typical lineshape of the optical absorption over a wide spectral range. The variation of the In_xGa_1−xN alloys with decreasing molar fraction of In is shown.