Theoretical and experimental studies in III-Nitride semiconductor alloys

Abstract

III-Nitride semiconductor materials have garnered significant attention among researchers due to their diverse applications stemming from their remarkable electrical and optical properties. This present thesis encompasses theoretical investigations conducted on InAlN and AlGaN for the purpose of designing light-emitting diodes (LEDs), along with experimental characterization experiments on BGaN thin films. The primary objective of this research is to delve deeply into the optoelectronic applications of InAlN and analyze the current state of BGaN. Theoretical studies were carried out on InAlN-based deep-ultraviolet (DUV) LEDs, with a particular focus on elucidating the polarization properties exhibited by this material when combined with AlGaN. Additionally, an estimation of the band alignment of this system was included, taking into account the available reported data. The intention behind this work is to underscore the importance of designing novel optoelectronic devices that incorporate ternary-to-ternary heterointerfaces. However, it is crucial to carefully consider both the advantages and disadvantages of such interfaces in terms of carrier injection efficiency and radiative efficiency. The experimental section of this thesis entailed the fabrication and characterization of BGaN thin films. A comprehensive understanding and development of this material are essential, as boron-alloys have garnered attention due to their unique properties. Nevertheless, there have been reports of epitaxial complications and theoretical limits associated with these alloys. In this section, we present the characteristics of the first conductive memory-effect-obtained p-type BGaN, doped with magnesium. Although the characterization of the reported samples includes techniques such as HRXRD, AFM, SEM, Hall, CTLM, SIMS, and CL, it is important to note that a more profound fundamental study is still underway. The relevance of this work can be summarized into two key aspects: Firstly, it provides valuable insights and descriptions of novel heterojunctions for ultraviolet LEDs from a physics perspective. Secondly, it contributes to material advancements in the pursuit of developing new ternary-alloys, offering a material science perspective.

Date of Award	Jun 2023
Original language	English (US)
Awarding Institution	Physical Sciences and Engineering
Supervisor	Xiaohang Li (Supervisor)