X-ray photoelectron spectroscopy and spectroscopic ellipsometry analysis of the p-NiO/n-Si heterostructure system grown by pulsed laser deposition

Abstract

• Band offset values of NiO/Si has been done by using X-ray photoelectron spectroscopy (XPS). • Energy band diagram is constructed by using the results obtained from XPS. • Optical properties of NiO/Si have been done by using Spectroscopic ellipsometry. • These findings will pave the way to design NiO/Si based optoelectronic devices. We report on the optical properties and the electronic structure of the p -NiO/ n -Si heterostructure system, established for optoelectronic applications in the UV spectral region. Pulsed laser deposition was used to deposit p- NiO onto n -Si to form the p -NiO/ n -Si heterojunction system. The optical constants (n, k) and the morphological properties were obtained by using a spectroscopic ellipsometry performed in the energy range of 1-5 eV, while the band-offset measurements of the p -NiO/ n -Si heterostructure were performed using X-ray photoelectron spectroscopy analysis. Our results show valence and conduction band offsets values between NiO and Si of about 0.34 ± 0.2 eV and 1.68 ± 0.2 eV, respectively. Valence and conduction band offset values assume that a type I band alignment is formed at the p -NiO/ n -Si interface, with the conduction band offset being higher than valence band offset. Based on these findings, an energy-band diagram of the heterojunction is constructed to predict the charge transport properties of the p -NiO/ n -Si system. We infer that photogenerated holes should experience a lower potential barrier for their transfer across the p -NiO/ n -Si interface than photoelectrons, which should experience a larger barrier. Our results pave the way towards the development of these p -NiO/ n -Si heterojunctions for UV detectors, solar cells, and self-biased device applications.