Nondestructive Characterization of ZnSe/GaAs Heterostructure Using Transverse Acoustoelectric Voltage Spectroscopy

Abstract

ABSTRACTThe electrical and optical properties of the heterostructure interface between high resistivity ZnSe and the semi-insulating GaAs substrate have been investigated using Transverse Acoustoelectric Voltage (TAV) spectroscopy. From the TAV spectra and the relative change of the TAV amplitude (ΔTAV/TAV), we have found the carrier type and concentration of ZnSe as well as the energy levels of various trap states at the heterostructure interface. The spectral behavior of the ΔTAV/TAV curves varied for samples of different ZnSe epilayer thickness. From the measurements, the surface recombination velocities (SRV's) were calculated. For the pseudomorphic ZnSe films on GaAs, a reduction in the SRV's was measured. As the thickness of the ZnSe film was increased, the various ΔTAV/TAV indicated presence of a large number of interface states due to the introduction of misfit dislocations.