Characterization of semi-insulating GaAs wafers by room-temperature EL2-related photoluminescence

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Abstract
Deep level photoluminescence (PL) associated with the dominant midgap donor EL2 in semi-insulating (SI) GaAs crystals has been observed for the first time at room temperature. A broad emission band with a peak at 0.65 eV was observed always in commercial undoped SI GaAs wafers. The association of the 0.65 eV band with the EL2 level has been verified on the basis of the semiquantitative agreement of the distribution on wafers between the PL intensity and the EL2 absorption. Room-temperature PL spectroscopy can be used as a powerful tool to investigate the nonuniformity of the EL2 distribution on commercial wafers with a high spatial resolution.