Contactless Electroreflectance, Photoluminescence and Time-Resolved Photoluminescence of GaInNAs Quantum Wells Obtained by the MBE Method with N-irradiation

Artikel i vetenskaplig tidskrift, 2011

The optical properties of GaInNAs quantum wells (QW) grown by molecular beam epitaxy with and without N-irradiation (i.e. grown by the classical method) were investigated by the contactless electroreflectance (CER), temperature-dependent photoluminescence (PL) and time-resolved PL (TRPL). From CER measurements it was concluded that one type of nitrogen nearest-neighbor environment (In-rich environment) is dominant for GaInNAs QWs grown with N-irradiation whereas various nitrogen environments are present for the reference GaInNAs QW (i.e. the sample obtained by the classical method). PL and TRPL measurements clearly show that the optical properties of GaInNAs QWs are affected mainly by the amount of the incorporated nitride atoms. It was observed that the PL decay time decreased from ∼200 to ∼40 ps when the nitrogen concentration is increased from 0.8 to 2.2%. In addition, the presence of As flux during N-irradiation reduces the amount of the incorporated nitrogen and simultaneously improves the optical quality of GaInNAs QWs (i.e. it weakens the carrier localization at low temperatures and improves the quantum efficiency of PL).