Unveiling hole-facilitated amorphisation in pressure-induced phase transformation of silicon

TL;DR

This study reveals that increased hole concentration significantly promotes amorphization during pressure-induced phase transformations in silicon and other semiconductors, with mechanisms supported by machine-learning-based calculations.

Contribution

It uncovers the role of hole carriers in facilitating amorphization during pressure-induced phase transformations, a factor previously overlooked.

Findings

Hole concentration enhances amorphization in silicon.

Machine-learning calculations elucidate the underlying mechanism.

Experimental confirmation in Ge, GaAs, and SiC.

Abstract

Pressure-induced phase transformation occurs during silicon (Si) wafering processes. \b{eta}-tin (Si-II) phase is formed at high pressures, followed by the transformation to Si-XII, Si-III or/and amorphous Si ({\alpha}-Si) phases during the subsequent decompression. While the imposed pressure and its release rate are known to dictate the phase transformation of Si, the effect of charge carriers are ignored. Here, we experimentally unveil that the increased hole concentration facilitates the amorphization in the pressure-induced phase transformation of Si. The underlying mechanism is elucidated by the theoretical calculations based on machine-learning interatomic potentials. The hole-facilitated amorphization is also experimentally confirmed to occur in the indented Ge, GaAs or SiC. We discover that hole concentration is another determining factor for the pressure-induced phase transformations of the industrially important semiconductors.