Determination of Exciton Reduced Mass and Gyromagnetic Factor of Wurtzite (InGa)As Nanowires by Photoluminescence Spectroscopy under High Magnetic Fields

Semiconductor nanowires (NWs) have the prospect of being employed as basic units for nanoscale devices and circuits. However, the impact of their one-dimensional geometry and peculiar crystal phase on transport and spin characteristics remains largely unknown. We determine the exciton reduced mass and gyromagnetic factor of (InGa)As NWs in the wurtzite phase by photoluminescence (PL) spectroscopy under very high magnetic fields. For 8 perpendicular to the NW (c) over cap axis, the exciton reduced mass is 10% greater than that expected for the zincblende phase and no field-induced circular polarization of PL is observed. For B parallel to an exciton reduced mass 35% greater than that of the zincblende phase is derived. Moreover, a circular dichroism of 70% is found at 28 T. Finally, an analysis of the PL line shape points at two Zeeman split levels, whose separation corresponds to an exciton gyromagnetic factor vertical bar g(e) - g(h)hJI vertical bar =5.8. These results provide a quantitative estimate of the basic iw electronic and spin properties of NWs and may guide a theoretical analysis of the band structure of these fascinating nanostructures.