Band alignment determination in few-layer exfoliated MoSe₂/SiO₂ interface using Synchrotron-based photoemission spectroscopy

Abstract

The ultrathin 2D-layered transition-metal dichalcogenides (TMDs) derived using solution-phase processes have engrossed great attention as an pivitol class of materials for optoelectronics and energy harvesting applications. In this work, we investigated the band alignment in the MoSe₂/SiO₂ heterointerface synthesized by employing simple, low cost and facile liquid exfoliation method. The high intense crystalline peak of the (002) plane and presence of Raman phononic mode (A_1g and E¹_2g modes) pointed toward the formation few monolayer thick MoSe₂ nanosheets upon liquid exfoliation. Corroboratively, the electronic structure was verified by XPS (X-ray photoelectron spectroscopy) and VBPES (valence band photoemission spectroscopy). Such that, utilizing both, we have determined a valence and conduction band offset of 4.06 ± 0.10 eV and 2.60 ± 0.10 eV at MoSe₂/SiO₂ heterointerface with a type-I band alignment.

Graphical abstract

The XPS spectra of the Mo 3d and Si 2p orbitals observed for MoSe₂ deposited on the SiO₂ substrate, (b) the observed core-level spectrum of the Si 2p orbital and the valence-band spectrum of the bare SiO₂ substrate, (c) the observed core-level spectrum of the Mo3d orbital and the valence-band spectrum of MoSe₂, and (d) schematic diagram of the energy band alignment at the few-layer and bulk MoSe₂/SiO₂ interfaces.