Experimental Investigations of Transport and Optical Properties of III-V QuantumWell Structures Grown via Molecular Beam Epitaxy Under Optimal Growth Conditions

摘要

A series of experimental studies have been conducted to explore; (1) theoptimization of transport and optical properties of quantum structures via control of the growth kinetics during molecular beam epitaxy and (2) relation of these properties with the structure design. As a result of a combined approach of material science, physics, and device engineering research, quantum structures with the best properties to-date, such as the resonant tunnelling diodes with high peak to valley ratio and large peak current density, inverted heterojunction structures with ultra-low density and high mobility suitable for the basic study of quantum Wigner solid states, etc., have been grown. Carrier scattering induced by interface roughening and interface trapped impurity and exciton scattering induced by band edge discontinuity fluctuations and alloy disorder have been demonstrated. A strong phenomenon of double resonant Raman scattering and optical phonon-electron resonance mixing is observed in specially designed structures. The possibility of in-situ fabrication of laterally confined nano-structures via growth on pre-patterned substrates has been explored. Additionally, benefits of using external beams to control the growth kinetics have been investigated. All these results are helpful towards a better understanding of the nature of quantum structures. They also provide a strong basis for the design and fabrication of some novel device structures in the future.