# Directional shift current in mirror-symmetric BC$_2$N

## TL;DR

This paper theoretically investigates the anisotropic shift current in mirror-symmetric BC₂N, revealing how mirror symmetry and band parity influence photoconductivity directionality and magnitude near the band gap.

## Contribution

It uncovers the role of mirror symmetry and band parity in dictating shift current anisotropy and magnitude in BC₂N, a noncentrosymmetric graphitic material.

## Key findings

- Photoconductivity is strongly anisotropic near the band gap.
- Certain tensor components vanish due to symmetry, affecting response direction.
- Band-edge photoconductivity is large and suitable for optical applications.

## Abstract

We present a theoretical study of the shift current in a noncentrosymmetric polytype of graphitic BC$_2$N. We find that the photoconductivity near the fundamental gap is strongly anisotropic due to the vanishing of particular tensor components not foretold by point-group symmetry arguments; this is a consequence of dipole selection rules imposed by mirror symmetry, which imply that the relative parities between valence and conduction bands are key for determining the directionality of the band-edge response. In addition, the band-edge photoconductivity turns out to be rather large, with the peak value occurring in an energy range suitable for optical manipulation