Influence of temperature and illumination on the electrical properties of p-ZnTe/n-CdTe heterojunction grown by molecular beam epitaxy

A set of p-ZnTe/n-CdTe heterojunctions were grown on conducting GaAs substrates by molecular beam epitaxy. The current density-voltage (J-V) and capacitance-voltage (C-V) characteristics measured in the temperature range 300-400 K were analysed in order to reveal the dominant carrier transport mechanisms through the junctions. The C-V measurements show that the device is linearly graded. The temperature dependence of the built-in potential and the impurity gradient of the device were determined. The deep defect states govern the current flow through the junctions. The measurements under the lower voltage region (V < 0.35 V) reveal at the p-ZnTe/n-CdTe interface, the presence of deep defect states with the activation energy of 0.52 eV. Under the higher forward bias voltage (V > 0.35 V), the space-charge-limited current governed the J-V characteristics with a single traps level, ΔE_t = 0.55 eV. The p-ZnTe/n-CdTe device under different illumination intensities exhibit a significant photosensitivity proving that this kind of heterostructure can be regarded as a good candidate for photodiode applications.