Influence of frequency and applied voltage on electrical characterization of p-ZnTe:N/CdTe:Mg/n-CdTe:I/GaAs grown by molecular beam epitaxy

A specialized heterojunction of p-ZnTe:N/CdTe:Mg/n-CdTe:I/GaAs for varicap and high response signal diode applications was epitaxially grown by using molecular beam epitaxy. Frequency dependence of the capacitance-voltage, conductance-voltage and series -resistance characteristics in the frequency spectrum from 10 kHz to 10 MHz at ambient temperature was investigated. An increase in the capacitance is observed especially at lower frequency range that can be attributed to the predominant effect of interface states. A negative capacitance is observed and is explained on the basis of the loss of interface charges or interface states localized between metal and semiconductor due to impact ionization process. The frequency and voltage dependencies of the series resistance were investigated and characteristic peaks were observed for the voltage dependence of series resistance under low-frequency range. Some important parameters such as barrier height, carrier concentration, cut off voltage were also estimated and discussed. The electrical characteristics of p-ZnTe:N/CdTe:Mg/n-CdTe:I/GaAs show a good candidacy for electronic and optoelectronic devices.