Pt/SeO2 optical receivers designed for terahertz and 5G/6G technologies

Abstract

Selenium oxide thin films are highly transparent optical layers proper for optoelectronic technology. However, SeO2 films are rarely studied and observed suffering from clustery surface morphology, low light absorbability and low dielectric constant. For this reason herein, in an attempt to enhance its properties, platinum nanosheets (10–50 nm) are used as plasmonic substrates to grow transparent selenium oxide thin films. The films are deposited onto glass and Pt substrates using thermal evaporation technique under a vacuum pressure of 10−5 mbar. Both films of the glass/SeO2 and Pt/SeO2 are characterized by the techniques of x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, optical spectrophotometry and impedance spectroscopy. While no significant effect of Pt nanosheets on the amorphous nature of structure of SeO2 is observed, remarkable enhancements in the light absorbability by 50 times and in dielectric constant by three times are achieved. In addition, Pt nanosheets form plasmonic interfaces resulting in improving the plasmon frequency, drift mobility and free carrier density of the films. Pt/SeO2 films showed plasmon frequency larger than 6.0 GHz and free carrier density of 1018 cm−3. Moreover, analysis of the terahertz cutoff frequency and impedance spectra have shown that the Pt/SeO2 interfaces can also be employed as terahertz receivers and as low pass filters suitable for 5G/6G technologies.