Band Gap Tuning of Twinned GaAsP Ternary Nanowires

Abstract

GaAs_1–<i>x</i>P_<i>x</i> ternary alloy nanowires have drawn much interest because their tunable band gaps, which range from the near-infrared to visible region, are promising for advanced and integrated nanoscale optoelectronic devices. In this study, we synthesized compositionally tuned GaAs_1<i>–x</i>P_<i>x</i> (0 ≤ <i>x</i> ≤ 1) alloy nanowires with two average diameters of 60 and 120 nm by vapor transport method. The nanowires exhibit exclusively twinned superlattice structures, consisting of zinc blende phase twinned octahedral slice segments between wurtzite phase planes. Smaller diameter and higher P content (<i>x</i>) result in shorter periodic superlattice structures. The band gap of the smaller diameter nanowires is larger than that of the larger diameter nanowires by about 90 meV, suggesting that the twinned superlattice structure increases the band gap. The increase in band gap is ascribed to the higher band gap of the wurtzite phase than that of the zinc blende phase