Optical studies of GaAs:C grown at low temperature and of localized vibrations in normal GaAs:C
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Infrared transmission and photoluminescence measurements were also carried out on heavily-doped GaAs:C films grown by molecular beam epitaxy at the standard 600 C temperature. The infrared results reveal, for dopings under 5 x 1019 cm-3, a linear relation between doping concentration and the integrated optical absorption of the carbon localized-vibrational-mode band. At higher dopings, the LVM integrated absorption saturates. Formation of CAs-CAs clusters is proposed as the mechanism of the saturation. The photoluminescence spectra were successfully analyzed with a simple model assuming thermalization of photoelectrons to the bottom of the conduction band and indirect-transition recombination with holes populating the degenerately doped valence band. The analysis yields the bandgap reduction and the Fermi-level-depth increase at high doping.
- Doctoral Dissertations