Field effect spectroscopy of CdSe-insulator interface states

We have developed a new technique termed field effect spectroscopy (FES) to probe semiconductor-insulator interface states optically. It consists of photoconductivity measurements of the semiconductor channel between source and drain of a gated thin-film transistor. By varying the gate voltage and thereby the potential at the insulator-semiconductor interface, one can vary the relative contributions of bulk and interface states to the resistivity of the semiconductor channel. FES results for a variety of Al2O3:CdSe and SiO2:CdSe interface reveal a strong dependence of interface state density on fabrication conditions.