Here, we report direct band gap transition for Gallium Phosphide (GaP) when alloyed with just 1–2 at% antimony (Sb) utilizing both density functional theory based computations and experiments. First principles density functional theory calculations of GaSbxP1−x alloys in a 216 atom supercell configuration indicate that an indirect to direct band gap transition occurs at x = 0.0092 or higher Sb incorporation into GaSbxP1−x. Furthermore, these calculations indicate band edge straddling of the hydrogen evolution and oxygen evolution reactions for compositions ranging from x = 0.0092 Sb up to at least x = 0.065 Sb making it a candidate for use in a Schottky type photoelectrochemical water splitting device. GaSbxP1−x nanowires were synthesized by reactive transport utilizing a microwave plasma discharge with average compositions ranging from x = 0.06 to x = 0.12 Sb and direct band gaps between 2.21 eV and 1.33 eV. Photoelectrochemical experiments show that the material is photoactive with p-type conductivity. This study brings attention to a relatively uninvestigated, tunable band gap semiconductor system with tremendous potential in many fields.
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The authors would like to thank and acknowledge the NSF SOLAR grant (DMS 1125909) for providing financial support and the Conn Center for Renewable Energy Research for experimental facilities.
Russell, H. B.; Andriotis, A. N.; Menon, Madhu; Jasinski, J. B.; Martinez-Garcia, A.; and Sunkara, M. K., "Direct Band Gap Gallium Antimony Phosphide (GaSbxP1-x) Alloys" (2016). Center for Computational Sciences Faculty Publications. 5.