Optically controlled n −Si/p −SeO2/p −SiO2 microwave resonators designed for 5G/6G communication technology

Abstract

Herein n-Si/p-SiO2 interfaces comprising layers of p-SeO2 are employed as an optically controllable microwave resonators. The stacked layers of SeO2 (500 nm) and SiO2 (50 nm) were deposited onto n-type Si thin crystals by the thermal evaporation technique under a vacuum pressure of 10-5 mbar. Ytterbium and Au metals were coated onto SiO2 and Si layers, respectively, to form Schottky arms. Energy band diagram analyses were performed to confirm the formation of doubled conduction and valence band offsets. These offsets create energy barriers and potential wells that contribute to the bistable behavior. Photo-impedance spectroscopic measurements were conducted on the device under blue light, demonstrating its ability to function as a light-power tunable microwave resonator and MOS capacitor. In the absence of light, negative capacitance (NC) effects were observed above a driving frequency of 1.07 GHz. As the device was exposed to light and the light power increased, the frequency range of NC effects shifted to higher driving frequencies. Furthermore, the range of NC effects became narrower with increasing light power, indicating a more limited frequency range for the manifestation of negative capacitance. In addition, n-Si/p-SeO2/p-SiO2 microwaves resonators displayed high cutoff frequency exceeding 0.10 THz at driving frequency of 1.07 GHz in the dark. The driving frequency also shifted toward larger values as light power is increased indicating the ability to optically control the cutoff frequency range and value. The high response of the capacitance, conductance, cutoff frequency spectra and the dependence of capacitance-voltage characteristics on incident light power nominate the device as microwave resonators and MOS electro-optic devices suitable for 5G/6G communication technology.