Design and performance of Yb/ZnS/C Schottky barriers

Abstract

In this work, ZnS thin films are deposited onto glass and transparent ytterbium substrates under vacuum pressure of 10−5 mbar. The effects of the Yb substrate on the structural, mechanical, optical, dielectric and electrical performance of the ZnS are explored by means of the energy dispersion X-ray analyzer, X-ray diffraction, UV–VIS spectroscopy, current-voltage characteristics and impedance spectroscopy techniques. The techniques allowed determining the lattice parameters, the grain size, the degree of orientation, the microstrain, the dislocation density, the optical and the excitonic gaps, the energy band offsets and the dielectric resonance and dispersion. The (111) oriented planes of glass/ZnS and Yb/ZnS exhibited 2.06% lattice mismatch between Yb and ZnS and degree of orientation values of 63% and 51.6%, respectively. The interfacing of the ZnS with Yb shrunk the energy band gap of ZnS by 0.50 eV. On the other hand, the electrical analysis on the Yb/ZnS/C Schottky device has revealed a rectification ratio of 3.48 × 104 at a biasing voltage of 0.30 V. The barrier height and ideality factor was also determined. Moreover, the impedance spectroscopy analysis have shown that the Yb/ZnS/C device is very attractive for use as varactor devices of wide tunability. The device could also be employed as microwave resonator above 1337 MHz.