Exploring p-type transparent conductive materials in conventional binary compounds beyond the equilibrium doping limit†

Abstract

Developing conventional binary semiconductors into p-type transparent conductive materials (TCMs) is hindered by low hole concentrations and large hole effective masses due to the low-energy and localized orbitals of their valence bands. Although alloying can improve p-type conductivity by raising energy levels and delocalizing the orbitals of valence bands, it often introduces more compensating defects, limiting the increase in hole concentration. Thermodynamic nonequilibrium growth has emerged as a mature method to increase particular defects and shift the Fermi level to a desirable position. Here, we use high-throughput first-principles calculations combined with high-temperature quenching to systematically explore p-type TCMs from 216 conventional binary compounds, focusing on stability, p-type dopability, hole effective masses and concentrations. We identify Li₂Te, Li-doped BeSe, Li-doped MgS, CaSe and Be-doped BN as potential efficient p-type TCMs, particularly with Li₂Te, CaSe and BN showing hole effective masses below 1.5m_e and concentrations up to 10¹⁸ cm⁻³ following high-temperature quenching. This study could revive interest in overlooked binary compounds for p-type TCMs and highlights that going beyond the equilibrium doping limit could address low hole concentrations in wide gap semiconductors.