Performance optimization of InGaN nanowire photocathode by Cs-Li-NF3 activation ratio

Abstract

In order to investigate the influence of different activating substances on photoemission performance of InGaN nanowires, we conduct theoretical studies on InGaN nanowires adsorbed by Cs-Li, Cs-NF₃ and Cs-Li-NF₃ using first-principles methods. Adsorption energies indicate that all structures are stable. However, excessive Cs atoms will jeopardize the stability of InGaN nanowires. When there are 3 Cs atoms on surface of InGaN nanowire, the three adsorption types of InGaN nanowires all show better electron emission performance. Among them, InGaN nanowires adsorbed by 3Cs-Li-NF₃ have relatively small work function and bandgap. We further explain the reason for high stability of InGaN nanowires adsorbed by 3Cs-Li-NF₃ using electron transfer and surface distance. In addition, 3Cs-Li-NF₃ adsorbed InGaN nanowires have very low reflectivity and high absorption coefficient in visible and near-infrared bands, so they have excellent optical absorption characteristics. Therefore, InGaN nanowire adsorbed by 3Cs-Li-NF₃ has the best photoemission performance theoretically. This study will provide possible ways to improve performance of InGaN nanowire photocathode.