p-TlGaSeS/n-BN heterojunction as a microwave filter and as a photovoltaic device

In this work, a p-n junction made of p-type TlGaSeS and n-type boron nitride (BN) is investigated and characterized. The bilayer was studied by means of capacitance-voltage characteristics, current-voltage characteristics and Bode signal and photovoltaic effect diagnostics. It was observed that the pTlGaSeS/n-BN bilayer exhibits negative capacitance values in the frequency range of 30-80 MHz. For an ac signal of 30 MHz, the built-in voltage and density of noncompensating carriers for the device are found to 1.06 eV and 1.72 x 10(12) cm(-3), respectively. The characteristic Bode curve analysis indicated that the bilayer behaves as a lowpass microwave filter that blocks all signals of frequencies larger than 1.28 GHz. The time constant for this device is 124 ps. In addition, the p-TlGaSeS/n-BN junction exhibited a well-pronounced photovoltaic effect. The device showed switching properties from low to high-current injection at a particular switching voltage. The switching voltage is sensitive to the light energy and intensity. It decreased systematically with increasing light intensity and energy. The device responsivity is similar to 7.64mAW(-1). The filtering and photovoltaic properties of the device suggest its use as an optoelectronic switch and as a microwave filter being suitable for multipurpose operations. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim