Modeling Electronic and Optical Properties of InAs/InP Quantum Dots

A theoretical investigation of electronic properties of self-assembled InAs/InP quantum dots (QDs) is presented, utilizing a novel two-step modeling approach derived from a double-capping procedure following QD growth processes, a method pioneered in this study. The electronic band structure of the QD is calculated by the newly established accurate two-step method, i.e., the improved strain-dependent, eight-band k p method. The impact of various QD structural parameters (e.g., height, diameter, material composition, sublayer, and inter-layer spacer) on electronic states’ distribution and transition energies is investigated. Analysis of carrier dynamics within QDs includes intraband and interband transitions. The calculation of the carrier transitions between two atomic states, providing insights into optical gain or loss within QDs, is in terms of dipole matrix element, momentum matrix element, and oscillation strength, etc. In addition, the time-domain, traveling-wave method (i.e., rate equations coupled with traveling-wave equations) is used to investigate the optical properties of QD-based lasers. Several optical properties of the QD-based lasers are investigated, such as polarization, gain bandwidth, two-state lasing, etc. Based on the aforementioned method, our key findings include the optimization of carrier non-radiative intraband relaxation through sublayer manipulation, wavelength control through emission blue-shifting and gain bandwidth via variation of sublayer, polarization control of QDs photoluminescence via excited states’ transitions, and the enhancement of two-state lasing in InAs/InP QD lasers by thin inter-layer spacers. This review offers comprehensive insights into QDs electronic band structures and carrier dynamics, providing valuable guidance for optimizing QD-based lasers and their potential designs.