Surface photovoltage spectroscopy characterization of a GaAlAs/InGaAs/GaAspseudomorphic high electron mobility transistor structure

Using room-temperature surface photovoltage spectroscopy (SPS), we have cha racterized a GaAlAs/InGaAs/GaAs pseudomorphic high electron mobility transi stor (pHEMT) structure. Signals have been observed from every region of the sample. From a line shape fit to the normalized first derivative of the su rface photovoltage signal with respect to photon energy, the two-dimensiona l electron gas density (N-s) was obtained and found to be in good agreement with Hall measurement. The Al composition and the properties of the GaAs/G aAlAs superlattice buffer layer also were obtained from the SPS spectrum. T he results demonstrate the considerable potential of SPS for the contactles s and nondestructive characterization of pHEMT structures at room temperatu re. (C) 2001 American Institute of Physics.