Jm. Ryan et al., THE EFFECTS OF TEMPERATURE AND OXYGEN CONCENTRATION ON THE PHOTOLUMINESCENCE OF EPITAXIAL METALORGANIC VAPOR-PHASE EPITAXY GAASO, Journal of applied physics, 76(2), 1994, pp. 1175-1179
Semi-insulating epitaxial GaAs:O prepared in a metalorganic vapor-phas
e epitaxy growth process using DEALO [(C2H5)2AlOC2H5] as the oxygen so
urce has been characterized by temperature-dependent (12-300 K) photol
uminescence. Oxygen-related deep level photoluminescence bands were de
tected at approximately 0.8 and approximately 1.1 eV. The relative int
ensities of the two bands were sensitive to both oxygen concentration
and temperature. At a given temperature, an increase in oxygen concent
ration led to an increase in the intensity of the lower energy band re
lative to the higher energy band. A similar effect occurred at a given
oxygen concentration as the temperature was raised. Band edge lumines
cence was also measured and was observed to quench when the oxygen con
centration exceeded approximately 10(18) cm-3. The results indicate th
at oxygen is incorporated differently in epitaxial GaAs than in bulk G
aAs. We propose that the difference is due to the incorporation of Al
when DEALO is used in the growth of epitaxial GaAs:O. We suggest equal
ly plausible microscopic models, based on the number of nearest-neighb
or Al associated with O and multiple charge states, to explain the pro
perties of the oxygen-related photoluminescence.