Hybrid $\mathbf{k\cdot p}$-tight-binding model for intersubband optics in atomically thin InSe films

TL;DR

This paper introduces a hybrid $oldsymbol{k ext{-}p}$-tight-binding model to predict intersubband optical transitions in atomically thin InSe films, covering IR and FIR ranges, with implications for optoelectronic applications.

Contribution

It develops a fully parametrized hybrid $oldsymbol{k ext{-}p}$ and tight-binding model for InSe films, enabling accurate prediction of intersubband optical properties across varying thicknesses.

Findings

Transition energies vary from 0.7 eV in bilayer to 0.05 eV in 15-layer InSe.

Model predicts oscillator strengths and linewidths at room temperature.

InSe films are promising for IR and FIR optoelectronic devices.

Abstract

We propose atomic films of n-doped $\gamma$-InSe as a platform for intersubband optics in the infrared (IR) and far infrared (FIR) range, coupled to out-of-plane polarized light. Depending on the film thickness (number of layers) of the InSe film these transitions span from $\sim 0.7$ eV for bilayer to $\sim 0.05$ eV for 15-layer InSe. We use a hybrid $\mathbf{k} \cdot \mathbf{p}$ theory and tight-binding model, fully parametrized using density functional theory, to predict their oscillator strengths and thermal linewidths at room temperature.