Optical properties of indium phosphide nanowire ensembles at various temperatures

Abstract

Ensembles that contain two types (zincblende and wurtzite) of indium phosphide nanowiresgrown on non-single crystalline surfaces were studied by micro-photoluminescence andmicro-Raman spectroscopy at various low temperatures. The obtained spectra arediscussed with the emphasis on the effects of differing lattice types, geometries, andcrystallographic orientations present within an ensemble of nanowires grown onnon-single crystalline surfaces. In the photoluminescence spectra, a typical Varshnidependence of band gap energy on temperature was observed for emissions fromzincblende nanowires and in the high temperature regime energy transfer fromexcitonic transitions and band-edge transitions was identified. In contrast, thephotoluminescence emissions associated with wurtzite nanowires were rather insensitive totemperature. Raman spectra were collected simultaneously from zincblende and wurtzitenanowires coexisting in an ensemble. Raman peaks of the wurtzite nanowires areinterpreted as those related to the zincblende nanowires by a folding of the phonondispersion.