Band offsets, dielectric dispersion and some applications of CdSe/GeO2 heterojunctions

Herein, the formation, structural, morphological, compositional, optical, dielectric, photoelectrical and electrical properties of the CdSe/GeO2 heterojunctions are explored. While the surface displayed formation of deficient GeO, the bulk of the films exhibited correct stoichiometry of GeO2 and CdSe. It is found that stacking of GeO2 onto CdSe enhances the crystallinity of CdSe by reducing the defects concentrations. It blue shifts the energy band gap of CdSe from 1.74 eV to 2.60 eV. The stacked layers of CdSe/GeO2 displayed conduction and valence band offsets of 2.34 eV and 1.23 eV, respectively. In addition, the Drude-Lorentz model analyses have shown that the coating of GeO2 onto CdSe, highly increases the drift mobility of charge carriers and tunes the plasmon frequency making it more appropriate for optoelectronic device applications. When exposed to light irradiation, an illumination intensity dependent photosensitivity is observed. The photoconduction mechanism is governed by the sublinear recombination with exponential trap distribution. Moreover, the capacitance -voltage characteristics of the device revealed metaloxide-semiconductor field effect transistors (MOSFET) characteristics. The built in potential for this device under reverse biasing conditions reached 4.74 eV.

Automated summary

The study explores the properties of CdSe/GeO2 heterojunctions, finding that stacking GeO2 onto CdSe enhances crystallinity, modifies the energy band gap, and increases carrier drift mobility. The coating is also shown to be suitable for optoelectronic device applications. Illumination intensity dependent photosensitivity and MOSFET characteristics were observed in the device.