Ricerc@Sapienza

The passivation of nitrogen by hydrogen in dilute nitride semiconductors or dilute nitrides (such as, GaAsN, GaPN and InAsN) is a powerful tool to tailor the electronic and lattice properties of this peculiar class of semiconductors. Dilute nitrides indeed feature great potential in various applicative fields, ranging from telecommunications, to photovoltaics to gas sensing. In this project, we aim at studying a surprising effect by virtue of which the H-induced electronic passivation of N atoms in dilute nitrides depends on the N atom lattice nearest neighbours. In particular, we will investigate this phenomenon in GaAsN, InAsN, and in the intermediate case represented by the InGaAsN alloy. Photoluminescence measurements already performed and being performed will be compared with first-principle supercell calculations to address the physical mechanism responsible for the lack of N passivation by H, whenever N is surrounded by In instead of As. This finding will be finally exploited to create on purpose In-rich regions by laser annealing, thus providing a further tool to modify on demand the electronic properties of dilute nitrides.