Structural stability and electronic structures of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>InP</mml:mi></mml:mrow></mml:math>nanowires: Role of surface dangling bonds on nanowire facets

Abstract

The structural stability and electronic properties of $\mathrm{InP}$ nanowires (NWs) are investigated based on first-principles pseudopotential calculations. In contrast to the bulk phase, zinc-blende (ZB) NWs are found to be less favorable over wurtzite (WZ) NWs, in which the surface dangling bonds (DBs) on the NW facets play a crucial role to stabilize the WZ structure. Our analysis of the NW cohesive energy based on the number of DBs also suggests the bistability forming both ZB and WZ NWs around $120\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ diameter and the formation of rotational twin structures around $400\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ diameter being consistent with experiments. Furthermore, the stable WZ NWs are found to be semiconducting whose characteristics are dependent on the surface DBs as well as the NW size and shape. The estimated oscillator strength also indicates the possibility of efficient light emission originating from the direct gap and geometrically restricted excitonic effects.