A reduction of the GaAs surface recombination velocity due to a heavily carbonhyphen;doped GaAs overlayer is reported. Metalorganic molecular beam epitaxy using trimethylgallium, triethylgallium, and elemental arsenic sources has been used to grow an epitaxial structure consisting of 1000 nm ofp=1times;1017cmminus;3capped with 10 nm ofp=1times;1020cmminus;3GaAs. Timehyphen;resolved photoluminescence (PL) and PL excitation spectroscopy showed thisp+/pstructure to have a 3.2 ns carrier lifetime and strong bandhyphen;edge PL emission, whose intensity was nearly constant over an excitation photon energy range of 1.5ndash;3.3 eV. The same wafer with thep+cap etched off exhibited a much shorter carrier lifetime and PL intensity that decreased exponentially with increasing photon energy, which is indicative of carrier losses to surface recombination. The specific contact resistivity of nonalloyed ohmic contacts to these heavily doped layers was observed to be in the mid 10minus;7OHgr;thinsp;cm2range, independent of measurement temperature from 77 to 340 K, suggesting a tunneling contact due to the narrow surface depletion layer.
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