Magneto-Optical Properties of Wurtzite-Phase InP Nanowires

The possibility to grow in zincblende (ZB) and/or wurtzite (WZ) crystal phase widens the potential applications of semiconductor nanowires (NWs). This is particularly true in technologically relevant III-V compounds, such as GaAs, In As, and InP, for which WZ is not available in bulk form. The WZ band structure of many III-V NWs has been widely studied. Yet, transport (that is, carrier effective mass) and spin (that is, carrier g-factor) properties are almost experimentally unknown. We address these issues in a well-characterized material: WZ indium phosphide. The value and anisotropy of the reduced mass (mu(exc)) and g-factor (g(exc)) of the band gap exciton are determined by photoluminescence measurements under intense magnetic fields (B, up to 28 T) applied along different crystallographic directions. mu(exc) is 14% greater in WZ NWs than in a ZB bulk reference and it is 6% greater in a plane containing the WZ (c) over cap axis than in a plane orthogonal to (c) over cap. The Zeeman splitting is markedly anisotropic with g(exc) = vertical bar g(e)vertical bar = 1.4 for B perpendicular to(c) over cap (where g(e) is the electron g-factor) and g(exc) = vertical bar g(e) - g(h,/) (/)vertical bar = 3.5 for B/ /(c) over cap (where g(h,/ /) is the hole g-factor). A noticeable B-induced circular dichroism of the emitted photons is found only for B/ /(c) over cap, as expected in WZ-phase materials.