Wurtzite MgSe: a promising candidate with excellent visible light transparency and p-type conductivity

Abstract

Transparent conducting materials (TCMs) play a vital role in optoelectronic fields. To date, commercially available TCMs are predominantly n-type, with excellent p-type TCMs being scarce. In this work, the electronic structures, optical properties, and hole effective mass of rock-salt, zinc blende, wurtzite, and nickel arsenide phases of MgSe were studied by utilizing the hybrid functional method based on the HSE scheme. The results showed that wurtzite MgSe was a promising candidate for p-type TCMs. At room temperature, the p-type electrical conductivity exceeded 150 S cm⁻¹ when the hole density reached 10²⁰ cm⁻³. To obtain a high hole density, the properties of intrinsic defects and extrinsic p-type defects were screened. We found that N substitutes for Se (labeled as N_Se) was a promising p-type defect in wurtzite MgSe. Thermodynamic equilibrium simulations showed that the hole density could reach ∼10¹⁶ cm⁻³. Using the thermodynamic equilibrium fabrication method, N_Se and N_int (the interstitial defect of the N atom) formed a defect complex, which had a minor effect on increasing the hole density. The nonequilibrium fabrication scheme was necessary to realize p-type conductivity. Our findings provide comprehensive support for understanding the properties of MgSe and open up new avenues for the design and exploration of TCMs.