Enhancing Optoelectronic Properties of Quantum Dot Heterostructures through Strain Coupling: Modelling and Characterization
by Dr. Jhuma Saha (Research Associate, Department of Electrical Engineering, Indian Institute of Technology Bombay)
Tuesday, November 19, 2019 from to (Asia/Kolkata)
Self-assembled InAs quantum dot (QD) systems have attracted the research community for many years owing to their superior optoelectronic properties, thus facilitating a wide range of applications. QDs have been exploited in various applications such as, LASERS, infra-red photodetectors, intermediate band solar cell (IBSC), etc. In recent years, extensive research on escalating the emission wavelength of InAs QD based devices has been done by implementing various techniques, such as variation of growth temperature, capping QDs with strain reducing ternary and quaternary alloys, and so on. However, there is constraint in emission wavelength (⁓1.3 μm) due to the reduced size of QDs, which is a consequence of In/Ga intermixing during the capping process. To overcome this, scientists have incorporated elements like N, Al and Sb in the capping material. In this talk, some theoretical and experimental investigations will be described, which would give a pathway to enhance the optoelectronic properties of InAs QD heterostructures. Consistent theoretical simulations were performed prior the growth of QD based structures. This is necessary for upgrading, and understanding the characteristics of QD structures, as it would save a lot of effort, time and money. The optoelectronic properties were improved through strain coupling, incorporation of combinational capping layers, and implementation of type-I and type-II band alignment. The emission wavelength of 1.7 μm has been achieved, which could be utilized in various optoelectronic applications.