Investigation of Electro Optical Properties of III to V Quantum Dot Epitaxial Structure for High Power Quantum Dot Laser Application

Abstract

This research work is concerned with the analysis of the electro-optical properties of IIIV semiconductor quantum dot (QD) heterostructure, which may lead to optimal material and device parameters for efficient quantum dot laser sources. This study will help laser designers and researchers to develop high-performance and thermally stable lasers. The development of stable laser sources has significant applications in optical communication, sensing, defense, medical and aesthetics. This work is contained in three parts described below. The first part of the work is concerned with spectroscopic studies performed on a molecular beam epitaxially grown eight-layer InAs/GaAs/AlGaAs quantum dot heterostructure. The thermal properties of InAs quantum dots are measured for carrier dynamics at the surface and interfacial layers of the heterostructure. newlineFinally, we demonstrated the temperature-dependent performance of the fabricated laser diodes measured in pulse and CW mode of operation. Operational characteristics of the fabricated QDLs, including the output power, threshold-current density, slope efficiency, and characteristic temperature, are measured to analyze the thermal stability. The performance of the fabricated diodes is found to compare well with the analytically calculated device parameters. Their performance has been analyzed by measuring threshold characteristics, output power and slope efficiency, which is one of the main concerns of the work presented in this thesis. The InAs/GaAs QD lasers developed in this thesis exhibit threshold current density with a high output power of 100 mW, showing high characteristic temperature. newline newline