Photovoltaic spectroscopy studies of strained InGaAs GaAs quantum wells

Photovoltaic (PV) spectroscopy measurements at various temperatures have been carried out on strained In0.18Ga0.82As/GaAs multiple quantum wells. Pronounced exciton peaks in the photovoltaic spectra up to room temperature were observed. At T approximate to 77 K, the PV spectra provided the best resolution of interband transition peaks and revealed most useful information on the electronic structure of the quantum wells. They have been identified as interband transitions in individual quantum wells by comparing the experimental data with theoretical calculations taking into account both strain and quantization effects. The temperature dependence of the transition energies shows that the band discontinuity and the strain effect of quantum wells are temperature independent. The exciton-phonon coupling and the inhomogeneous effect due to alloy disorder and interface roughness are also determined from the linewidth analysis. The results show that the photovoltaic measurement is a simple and powerful technique for investigating the electronic properties of low-dimensional materials.