Identification of band-edge optical transition types in tensile strained quantum wells

A new characterization technique based on photoluminescence excitation spectroscopy (PLE) which allows simple and direct identification of band-edge transition types in quantum wells is developed. A ratio curve is generated by pointwise division of one PLE spectrum by a second PLE spectrum. The two PLE spectra are obtained using orthogonal polarizations of the excitation beam, which is incident on the sample surface at an oblique angle, and the transition types near the band edge are identified by simple visual inspection of the ratio curve. The authors describe and assess the theoretical foundation for the ratio method, detail the experimental procedure, present PLE spectra and ratio curves for several quantum wells, and determine optimum experimental conditions and the physical origin of features in the ratio curve through investigation of the influence of several experimental parameters