ABSTRACT
The transmission spectra of the sample discussed above and another sample with 6 ML thick wells are shown in Fig.3. The experimental (theoretical) ISB peaks are at 0.64 (0.80) eV and 0.71 (0.88) eV for the samples with 7 ML and 6 ML thick wells, respectively. The calculation was conducted in the framework of the effective mass
approximation including band nonparabolicity and strain effect using the band offsets determined by model-solid theory. There is a relatively large deviation between the calculated and measured ISBT energies. The observed red shift of the ISBT indicates that a significant change in the shape of the QW profile has occurred. Due to the large conduction band offset in this system, -1.52 eV, the composition grading at the interfaces deduced from the X-ray data analysis can explain the shift to lower energies of the ISBT. Thus the inhomogeneity along the interfaces is mainly responsible for the observed relatively broad peaks.
