NONCONTACT PHOTOTHERMAL INFRARED RADIOMETRIC DEEP-LEVEL TRANSIENT SPECTROSCOPY OF GAAS WAFERS

A novel infrared photothermal radiometric deep-level transient spectroscopy (PTR-DLTS) has been developed for semiconductor noncontact characterization and applied to GaAs wafer diagnostics. The technique is based on rate-window detection combined with wafer temperature ramping. Unlike other deep-level methodologies, PTR-DLTS should be easily implemented remotely for on-line or off-line impurity/electronic defect diagnostics and enjoys high spectral peak separation and spatial resolution limited only by the pump laser beam focus (greater than or equal to 1 mu m). The impurity level in a Cr-compensated semi-insulating GaAs wafer has been detected at similar to 375 K using the 514 nm line of an Ar+ laser. A Te-doped GaAs sample exhibited behavior consistent with photoinjected carrier lifetime enhancement due to surface state (trap) thermal filling at elevated temperatures. (C) 1995 American Institute of Physics.