Stable Ultra-thin CdTe Crystal: A Robust Direct Gap Semiconductor

TL;DR

This study uses density functional theory to analyze the structural, vibrational, and electronic properties of a stable, ultra-thin CdTe crystal, highlighting its potential for strain-tunable nanoscale electronic devices.

Contribution

It introduces a detailed computational analysis of ultra-thin CdTe, revealing its stability, anisotropic electronic properties, and strain-dependent band gap behavior, which are novel insights for 2D semiconductors.

Findings

Ultra-thin CdTe has an 8-atom primitive cell with surface reconstructions.

The structure is dynamically stable based on vibrational spectra.

The band gap remains direct and is tunable by strain.

Abstract

Employing density functional theory based calculations, we investigate structural, vibrational and strain-dependent electronic properties of an ultra-thin CdTe crystal structure that can be de- rived from its bulk counterpart. It is found that this ultra-thin crystal has an 8-atom primitive unit cell with considerable surface reconstructions. Dynamic stability of the structure is predicted based on its calculated vibrational spectrum. Electronic band structure calculations reveal that both electrons and holes in single layer CdTe possess anisotropic in-plane masses and mobilities. Moreover, we show that the ultra-thin CdTe has some interesting electromechanical features, such as strain-dependent anisotropic variation of the band gap value, and its rapid increase under per- pendicular compression. The direct band gap semiconducting nature of the ultra-thin CdTe crystal remains unchanged under all types of applied strain. With a robust and moderate direct band gap, single-layer CdTe is a promising material for nanoscale strain dependent device applications.