Polarized photocurrent spectroscopy of wurtzite InAs nanowires*

Polarized photocurrent measurements on devices fabricated from wurtzite InAs nanowires reveal the energy band structure and optical transitions in this hexagonal material. InAs nanowires were grown by MOCVD and dispersed onto a Si++/SiO2 substrate. Aluminum contacts were placed at the two ends of nanowire using photolithography. Experiments were performed with light polarized along the long axis of the nanowire (the c-axis), as well as perpendicular to the c-axis. The data displays a 0.43 eV band gap energy at room temperature, which is ~70 meV larger than observed in bulk zinc blende material. Valence band splittings are in a good agreement with theory. The transition from the A hole band to the conduction band is only seen for perpendicular polarized light. The transitions from B and C to the conduction band are seen for both polarizations in accordance with group theory.