# Growth of Hg0.7Cd0.3Te on Van Der Waals Mica Substrates via Molecular Beam Epitaxy

## TL;DR

This paper explores growing Hg0.7Cd0.3Te on mica substrates using molecular beam epitaxy, finding optimal conditions for better material quality.

## Contribution

The study introduces a novel method for growing Hg0.7Cd0.3Te on van der Waals mica substrates with weak interface interaction.

## Key findings

- The (111) orientation is preferred for Hg0.7Cd0.3Te growth on mica due to better lattice matching.
- Optimal growth conditions are 190 °C and 4.5 × 10−4 Torr Hg flux, yielding high crystalline quality and smooth surface morphology.
- Microtwin defects and high etch pit density are observed, affecting material quality despite optimal conditions.

## Abstract

In this paper, we present a study on the direct growth of Hg0.7Cd0.3Te thin films on layered transparent van der Waals mica (001) substrates through weak interface interaction through molecular beam epitaxy. The preferred orientation for growing Hg0.7Cd0.3Te on mica (001) substrates is found to be the (111) orientation due to a better lattice match between the Hg0.7Cd0.3Te layer and the underlying mica substrate. The influence of growth parameters (mainly temperature and Hg flux) on the material quality of epitaxial Hg0.7Cd0.3Te thin films is studied, and the optimal growth temperature and Hg flux are found to be approximately 190 °C and 4.5 × 10−4 Torr as evidenced by higher crystalline quality and better surface morphology. Hg0.7Cd0.3Te thin films (3.5 µm thick) grown under these optimal growth conditions present a full width at half maximum of 345.6 arc sec for the X-ray diffraction rocking curve and a root-mean-square surface roughness of 6 nm. However, a significant number of microtwin defects are observed using cross-sectional transmission electron microscopy, which leads to a relatively high etch pit density (mid-107 cm−2) in the Hg0.7Cd0.3Te thin films. These findings not only facilitate the growth of HgCdTe on mica substrates for fabricating curved IR sensors but also contribute to a better understanding of growth of traditional zinc-blende semiconductors on layered substrates.