Correlation of photoluminescence and deep trapping in metalorganic chemical vapor deposited AlxGa1−xAs (0≤x≤0.40)

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Abstract
Shallow and deep level photoluminescence (PL) in metalorganic chemical vapor deposition grown AlxGa1−xAs (0≤x≤0.40) are studied. Two sets of samples grown under different conditions are compared. The growth conditions are chosen to produce a large density of deep levels in one case and to minimize the deep level density in the other case. The 0.82‐eV EL2 electron trap and four other dominant electron traps with activation energies ET ranging from 0.25 to 0.62 eV are identified. The concentrations of the four other traps are observed to increase with Al content in those samples grown under trap‐producing conditions, and the traps are nearly absent in the other set of samples. The PL intensity is inversely proportional to trap concentrations. The trap densities are related to background contamination in the growth ambient, most likely H2O and O2, leading to the speculation that two traps with ET=0.35 eV and ET=0.25 eV involve Al and O complexes. Hole traps have also been observed but show no definite trends with x or the growth ambient. Radiative centers up to 400 meV deep exhibit more intense PL in samples grown under larger V/III ratios.