Electronic properties of the Sn1-xPbxO alloy and band alignment of the SnO/PbO system: a DFT study

Abstract

Tin monoxide (SnO) has attracted attention due to its p-type character and capability ofambipolar conductivity when properly doped, properties that are beneficial for the realization ofcomplementary oxide thin film transistors technology, transparent flexible circuits andoptoelectronic applications in general. However, its small fundamental band gap (0.7 eV) limitsits applications as a solar energy material, therefore tuning its electronic properties is necessaryfor optimal performance. In this work, we use density functional theory (DFT) calculations toexamine the electronic properties of the Sn1-xPbxO ternary oxide system. Alloying with Pb byelement substitution increases the band gap of SnO without inducing defect states in the bandgap retaining the anti-bonding character of the valence band maximum which is beneficial for p-type conductivity. We also examine the properties of the SnO/PbO heterojunction system interms of band alignment and the effect of the most common intrinsic defects. A broken gap bandalignment for the SnO/PbO heterojunction is calculated, which can be attractive for energyconversion in solar cells, photocatalysis and hydrogen generation.