Enhanced cation-substituted p-type doping in GaP from dual surfactant effects

We report first principles calculations demonstrating a dual-surfactant effect of Sb and H on enhanced Zn, Mg, Be and Cd incorporation in organometallic vapor phase epitaxially grown GaP films. The combined effects of Sb and H lower significantly the film doping energy during the epitaxial growth of all the p-type dopants studied, while neither Sb nor H can work alone as effectively. The role of H is to satisfy the electron counting rule. The role of Sb is to serve as an electron reservoir to help electron redistribution. We also predict that due to the low electronegativity of Mg, Sb and H will enhance Mg doping the least among these dopants because Mg as an electron reservoir itself may negate the electron reservoir effect of Sb. Our findings provide an important general physical understanding for p-type doping in III—V thin films.