IDENTIFICATION OF DEEP-LEVEL STATES IN ELECTRONIC MATERIALS BY OPTICALLY STIMULATED DEEP LEVEL IMPEDANCE SPECTROSCOPY

Optically stimulated deep level impedance spectroscopy (OS-DLZS) is suggested for analysis of electronic transitions involving deep-level states in semiconductors with large bandgaps. The technique is based on interpretation of both the real and imaginary components of the impedance response measured over a continuous range of electrical frequencies under sub-bandgap illumination. The application of OS-DLZS is illustrated for a ZnS:Mn electroluminescent panel and for ZnO varistors. The lower frequency range of the impedance spectrum is shown to be more sensitive to electronic transitions caused by monochromatic sub-bandgap illumination than is the capacitance measured at high frequency.