First principles calculation of shift current in chalcopyrite semiconductor ZnSnP$_2$

TL;DR

This study uses first principles calculations to analyze the shift current in the non-inversion symmetric chalcopyrite semiconductor ZnSnP$_2$, revealing significant photovoltaic responses comparable to known ferroelectric materials.

Contribution

It provides the first theoretical calculation of shift current in ZnSnP$_2$, demonstrating its potential for photovoltaic applications due to large nonlinear optical effects.

Findings

Shift current magnitude is comparable to other ferroelectric semiconductors.

Peak response occurs several eV above the bandgap.

Main contributions come from P-3$p$ and Sn-5$p$ orbitals.

Abstract

The bulk photovoltaic effect generates intrinsic photocurrents in materials without inversion symmetry. Shift current is one of the bulk photovoltaic phenomena related to the Berry phase of the constituting electronic bands: photo-excited carriers coherently shift in real space due to the difference in the Berry connection between the valence and conduction bands. Ferroelectric semiconductors and Weyl semimetals are known to exhibit such nonlinear optical phenomena. Here we consider chalcopyrite semiconductor ZnSnP$_2$ which lacks inversion symmetry and calculate the shift current conductivity. We find that the magnitude of the shift current is comparable to the recently measured values on other ferroelectric semiconductors and an order of magnitude larger than bismuth ferrite. The peak response for both optical and shift current conductivity, which mainly comes from P-3$p$ and Sn-5$p$ orbitals, is several eV above the bandgap.