MODULATION SPECTROSCOPY STUDY OF AN INGAAS GAAS-STRAINED ASYMMETRIC TRIANGULAR QUANTUM-WELL HETEROSTRUCTURE/

We have studied modulation spectra related to the intersubband transit ions at 300K and 20K from an InGaAs/GaAs-strained asymmetric triangula r quantum well (ATQW) heterostructures fabricated by molecular beam ep itaxy using the digital alloy compositional grading (DACG) method. A c areful analysis of the spectra has led to the identification of variou s excitonic transitions, mnh(1), between the m-th conduction band stat e to the n-th heavy (light)-hole band state. Comparison of the observe d intersubband transitions with a theoretical calculation based on the envelope function model, including the effects of strain provided a s elf-consistent verification that the DACG method produced the intended ATQW composition profile.