Date of Award
8-1-2019
Degree Name
Doctor of Philosophy
Department
Electrical and Computer Engineering
First Advisor
Ahmed, Shaikh
Abstract
Recently, nonpolar InGaN/GaN optoelectronic structures have been widely studied for applications in ultrafast communication, solid-state lighting, solar cell, sensing, photonic integrated circuits and quantum cryptography. When grown in a core-shell architecture (where the nonpolar, multiple disk active region is radially grown on the sidewall of a hexagonal GaN nanowire), these devices exhibit superior properties that mainly arise from the availability of a larger active region. Recently, the viability of using such architectures in electrically injected, low-threshold single-nanowire laser operating at room temperature has been experimentally demonstrated. In contrast, axially (or expitaxially) grown disk-in-wire structures suffer from a smaller gain-volume and, thus, have failed to produce optically pumped lasing emissions. From fundamental physics point of view, the benefits of using nonpolar m-axis and a-axis oriented InGaN/GaN in the active region are as follows: a) lesser degree of lattice mismatch, resulting in a weaker strain field; b) absence of spontaneous (pyroelectric) polarization; c) smaller piezoelectric polarization, induced internal potential, and electric field in the carrier transport
Access
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