DOI
https://doi.org/10.25772/7GNE-R876
Defense Date
2013
Document Type
Thesis
Degree Name
Master of Science
Department
Physics and Applied Physics
First Advisor
Michael Reshchikov
Second Advisor
Alison Baski
Abstract
The development of gallium nitride (GaN) light emitting devices has reached extraordinary echelons. As such, the characterization and analysis of the behavior of GaN materials is essential to the advancement of GaN technology. In this thesis, the effect of temperature on the optical and electrical properties of p-type GaN is investigated. The GaN samples used in this work were grown by various methods and studied by Kelvin probe and photoluminescence (PL) techniques. Specifically, the surface photovoltage (SPV) behavior and PL data were analyzed at different temperatures and illumination intensities. Using the SPV results, we show that p-type GaN exhibits n-type conductivity at low temperatures (80 K). If the sample is heated beyond a characteristic temperature, TC, the conductivity reverts to p-type. This temperature of conversion can be tuned by varying the illumination intensity. We explain this conductivity conversion using a simple, one-acceptor phenomenological model. Temperature-dependent PL measurements taken on Mg-doped p-type GaN layers show abrupt and tunable thermal quenching of the PL intensity. This effect is explained by a more complex model but with the same assertions, that the system must undergo a change in conductivity at low temperatures and under UV illumination. It is necessary to understand the observed behaviors, since the implications of such could have an effect on the performance of devices containing p-type GaN materials.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
May 2013