Performance of Broken Gap MoO3/ZnS Heterojunctions as Abrupt Electronic Switches, MOSFETs, Negative Capacitance FETs and Bandpass Filters Suitable for 3G/4G Technologies

Abstract

Herein, MoO3/ZnS broken gap heterojunction devices are fabricated by thermal evaporation under a vacuum pressure of 10−5 mbar. The devices are characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, ultraviolet-visible light spectroscopy and impedance spectroscopy. Three channels composed of one Schottky arm (Ag/ZnS) and two ohmic arms (Au, C)/ZnS are formed on the epilayer of the amorphous (MoO3)/polycrystalline (ZnS) heterojunctions. Optical analyses show that the broken gap devices exhibit valance and conduction band offsets of 2.6 eV and 2.8 eV, respectively. Practical tests on the devices show that they can behave as abrupt electronic switches with biasing independent current rectification ratios of 2.7 × 103 at an applied voltage of 0.14 V. The Au/MoO3/ZnS/Ag channels displayed metal oxide field effect transistor characteristics as they are effective in the frequency domain of 3.0–20 MHz. In addition to its performance as a negative capacitance FET, the broken gap device can be employed as a radiowave/microwave cavity with notch frequency (fn) values of 0.86 GHz, 1.16 GHz, 1.69 GHz and 1.75 GHz. The ideality of the resonators was observed at 1.16 GHz for the Au/MoO3/ZnS/C channel. This channel displayed bandpass filter characteristics with voltage standing wave ratios of 1.0 and return loss values of 40.2 dBs.