Energy Band and Absorption Coefficient of Quantum Dots in a Well Structure

Building on the effective-mass envelope function theory, this paper focuses on the study of the energy band and the absorption coefficient of $InAs//In_{x}Ga_{1 - x}As$ quantum dots in a well (DWELL) structure. In contrast to $InAs//In_{0.15}Ga_{0.85}As$ quantum DWELL, the $InAs//In_{0.2}Ga_{0.8}As$ quantum DWELL has lower ground states. With the thickness of $In_{0.15}Ga_{0.85}As$ layer changing from 7 nm to 9 nm and $In_{0.2}Ga_{0.8}As$ layer changing from 9 nm to 12 nm, the calculation shows that their absorption coefficient spectra takes a red shift in the long-wave infrared and far-infrared ranges, respectively. Moreover, when the thickness of the $In_{x}Ga_{1 - x}As$ layer is defined as 9 nm, the absorption coefficient spectra of $InAs//In_{0.2}Ga_{0.8}As$ DWELL shows a obvious red shift comparing with that of $InAs//In_{0.15}Ga_{0.85}As$ DWELL.