Date of Award

2017

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Department of Physical Sciences

First Advisor

Dr. Tomasz Ochalski

Abstract

In the last century, semiconductor research has led to significant changes in the fields of communication, medicine, the environment, and many others. Semiconductor devices provide a relatively simple and effective way to convert electrical energy to light and vice versa. Devices based on semiconductor materials of various kinds provide interaction of an electromagnetic signal in the range of wavelengths with a medium. Examples of such devices are LED lamps, photovoltaic cells, thermometers, gas sensors, cameras, and many others. The study of various semiconductors broadens the range of application of photonics. This work is based on the study of materials which provide light generation around 2μm. Semiconductors with properties of that kind are Ge, InAs, and InSb. These materials are not as widely discussed in literature as InGaAs is, which is widely used in telecommunications. Main application of 2 μm materials is gas sensing. However, they also have the potential for telecommunications when using ZBLAN fiber for communication at short distances or utilising quantum constraints for tuning the band energies. In this work, attention is focused on Ge and InAs. Ge has a low lattice index and is more promising for silicon integration. Silicon is the basis for modem electronics and the possibility of direct integration with photonics will provide a new generation of devices with optical communication between components. For the design of the Ge energy structure, tensile stress is applied by growth of Ge on the lattice-mismatched material, and also investigated. As an alternative approach for band engineering nanoscale structures of GeSn are also studied. The optical properties of the materials were studied by the methods of photoluminescence and photoreflection. Also part of the work was devoted to the research of InAs as a powerful photonics material grown on an InP substrate. Manufactured materials and the lasers based on quantum confined InAs active medium were characterised as semiconductor sandwiches, Fabry-Perot lasers and single mode distributed feedback lasers. A method of frequency difference in a nonlinear crystal is used to provide a time resolution of the measured spectra. Based on this material, a laser with emission corresponding to NH3 gas spectral fingerprint was developed.

Comments

Thesis prepared in association with Tyndall National Institute.

Submitted to Cork Institute of Technology, July 2017.

Access Level

info:eu-repo/semantics/openAccess

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