Absorption spectroscopy studies of strained InGaAs/GaAs single-quantum wells

Abstract

Strained In0.20Ga0.80As/GaAs single-quantum well (SQW) structures with the GaAs capping layer thickness ranging from 5 to 500 nm have been studied directly by absorption spectroscopy. The absorption peaks are shifted to lower energy while the GaAs capping layer thickness decreases due to the strain relaxation in InGaAs/GaAs SQW structures induced by the GaAs capping layer. The best fit gives the conduction-band offset ratio Qc=0.70±0.05. The pronounced exciton peaks are observed in the absorption spectra at room temperature. The strength of the exciton–phonon coupling is determined from linewidth analysis and is found to be much larger than that of strained InGaAs/GaAs MQW structures.