Propriedades opticas de nanofios de InP / Optical properties of InP nanowires
AUTOR(ES)
Everton Geiger Gadret
DATA DE PUBLICAÇÃO
2009
RESUMO
Optical properties of InP nanowires grown by Vapor-Liquid-Solid (VLS) method in a Chemical Beam Epitaxy system were investigated by using micro-photoluminescence spectroscopy varying experimental parameters such as excitation power, emitted signal polarization and sample temperature. Due to polytypism (InP in cubic, zincblende (ZB), and hexagonal, wurtzite (WZ) phases), this structure becomes interesting by the point of view of optical properties, due to type?II InP?ZB/InP?WZ interfaces. We have noticed that there are few informations in the literature about electronic structures of InP in wurtzite phase, because this phase has been only reported in nanowires. We focused, thus, our investigation about electronic structure of nanowires having both structural phases. We identified optical emissions from type II quantum wells in InP nanowires as well as emissions involving shallow acceptor impurities and InP?WZ gap recombination. The type II quantum well optical emission is dominant at low temperatures, below 100K, which is in 1,44 ? 1,46eV range at 10K. This emission behavior as function of temperature, excitation power and light polarization is in agreement with the proposed structure and is supported by transmission electronic microscopy (TEM) imagem. The shallow impurity emission is ~ 43meV below the quantum well emission, a value close to the carbon acceptor in InP in cubic phase. The optical emission associated to the InP?WZ at 1,49eV (10K) was observed from temperatures of 10K to 300K, in agreement with results reported in literature. We also observed an additional optical transition related to the carrier localized at the barriers of the quantum wells at at high temperatures, above 150K.
ASSUNTO(S)
nanostructures micro-photoluminescence semiconductor nanowires nanofios semicondutores - propriedades óticas micro-fotoluminescencia nanoestrutura
