Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 89: Optical Properties II

HL 89.6: Vortrag

Freitag, 18. März 2011, 11:30–11:45, POT 251

Effect of localized boron impurities on the line shape of the fundamental band gap transition in photomodulated reflectance spectra of (B,Ga,In)As — •Thomas Sander¹, Jörg Teubert¹, Peter J. Klar¹, Andrew Lindsay², and Eoin P. O’Reilly^2,3 — ¹Institute of Experimental Physics I, Justus-Liebig-University Giessen, Germany — ²Tyndall National Institute, Lee Maltings, Cork, Ireland — ³Department of Physics, University College Cork, Ireland

Photomodulated reflectance (PR) spectra of (B,Ga,In)As epilayers reveal unusual changes of the fundamental band gap PR line shape with temperature and hydrostatic pressure. We show that these changes arise because temperature variation or hydrostatic pressure shifts the conduction band edge (CBE) into resonance with boron-related cluster states. The resulting line shape changes are described by a level repulsion model which yields states of mixed character with an exchange of oscillator strengths. This model is corroborated by theoretical calculations which show a finite density of boron cluster states above the CBE at room temperature, with appropriate symmetry to couple to the CBE states.