Defect physics and electronic properties of Cu3PSe4 from first principles

TL;DR

This study uses first-principles calculations to analyze the defect physics and electronic properties of Cu3PSe4, revealing key defects responsible for its p-type behavior and demonstrating the effectiveness of the GGA+U method.

Contribution

It provides a detailed first-principles analysis of defect energetics and electronic properties of Cu3PSe4 using GGA+U, improving accuracy over standard methods.

Findings

Copper vacancy V_Cu and P_Se antisite defects cause p-type conductivity.

GGA+U method yields more accurate defect energies than standard GGA.

Cu3PSe4 is thermodynamically stable with potential for photovoltaic applications.

Abstract

The p-type semiconductor Cu3PSe4 has recently been established to have a direct bandgap of 1.4 eV and an optical absorption spectrum similar to GaAs [Applied Physics Letters, 99, 181903 (2011)], suggesting a possible application as a solar photovoltaic absorber. Here we calculate the thermodynamic stability, defect energies and concentrations, and several material properties of Cu3PSe4 using a wholly GGA+U method (the generalized gradient approximation of density functional theory with a Hubbard U term included for the Cu-d orbitals). We find that two low energy acceptor-type defects, the copper vacancy V_Cu and the phosphorus-on-selenium antisite P_Se, establish the p-type behavior and likely prevent any n-type doping near thermal equilibrium. The GGA+U defect calculation method is shown to yield more accurate results than the more standard method of applying post-calculation GGA+U-based bandgap corrections to strictly GGA defect calculations.