Optically detected kinetic carrier transfer in InP-GaP lateral nanowires

Abstract

The temperature dependence of the linearly polarized photoluminescence (PL) of an InP-GaP lateral nanowire (LNW) structure grown by a lateral composition modulation technique was measured. Two prominent PL peaks were observed at 5 K from each cross-polarization direction (the P//[110] and P//[1 1 0] crystal directions). By varying the excitation laser power, the higher-and lower-energy peaks were identified as the transitions from the InGaP bulk layers and from the nanowire structure, respectively. The transitions from the InGaP bulk exhibit a free-to-bound exciton transition below 60 K. For the nanowire transitions, the polarization directions parallel to the [110] and [110] directions are recognized as recombination from the InP conduction band to the InP (type I) and GaP (type II) valence band, respectively. The temperature dependent polarization degree and the integrated PL intensity of the bulk InGaP transition show thermal equilibrium behavior, whereas the type I LNW PL transition shows kinetic carrier transfer behavior below similar to 50 K. We also confirm that the temperature dependent polarization degree for the LNW transition supports the kinetic carrier transfer.