Unlocking high hole mobility in diamond over a wide temperature range via efficient shear strain

TL;DR

This study demonstrates that applying slight compressive shear strain along the [100] direction significantly enhances diamond's hole mobility across a wide temperature range, overcoming temperature-dependent limitations.

Contribution

It reveals that shear strain along [100] effectively increases hole mobility in diamond by breaking symmetry and reducing electron-phonon scattering, a novel strain engineering approach.

Findings

Hole mobility increases by approximately 800% at 800 K with 2% shear strain.

Shear strain along [100] significantly reduces temperature dependence of hole mobility.

The strategy can be extended to other face-centered cubic semiconductors.

Abstract

As a wide bandgap semiconductor, diamond holds both excellent electrical and thermal properties, making it highly promising in the electrical industry. However, its hole mobility is relatively low and dramatically decreases with increasing temperature, which severely limits further applications. Herein, we proposed that the hole mobility can be efficiently enhanced via slight compressive shear strain along the [100] direction, while the improvement via shear strain along the [111] direction is marginal. This impressive distinction is attributed to the deformation potential and the elastic compliance matrix. The shear strain breaks the symmetry of the crystalline structure and lifts the band degeneracy near the valence band edge, resulting in a significant suppression of interband electron-phonon scattering. Moreover, the hole mobility becomes less temperature-dependent due to the decrease of electron scatterings from high-frequency acoustic phonons. Remarkably, the in-plane hole mobility of diamond is increased by approximately 800% at 800 K with a 2% compressive shear strain along the [100] direction. The efficient shear strain strategy can be further extended to other semiconductors with face-centered cubic geometry.