Author ORCID Identifier
https://orcid.org/0000-0002-8152-6316
Defense Date
2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Nanoscience and Nanotechnology
First Advisor
Michael Reshchikov
Abstract
Annealing is a critical process in modern GaN technology, essential for achieving p-type conductivity by activating the MgGa acceptor, as first demonstrated by Shuji Nakamura in the early 1990s. Despite the omnipresence of hydrogen as an impurity in GaN crystals, the precise mechanisms governing hydrogen diffusion and acceptor passivation remain only partially understood. The presented research investigates the effects of annealing-induced activation and hydrogen passivation on C and Be acceptors in GaN grown by MOCVD, HVPE, and MBE methods. We explored these effects by using several annealing techniques, gas compositions, and thermal regimes. A transient behavior between the CN and CN-Hi complex was observed when samples were annealed in N2 and N2 + H2 atmospheres. Annealing in vacuum ambient revealed an unexpected behavior in acceptor-related PL bands, demonstrating that passivation of CN and BeGa can occur at temperatures as low as 200 °C and 350 °C, respectively. Both CN and BeGa exhibited a U-shaped pattern of passivation and activation, suggesting a common mechanism of hydrogen diffusion. In Be-doped MBE samples, high-temperature passivation involving VN was observed. Finally, using UHPA, activation of a shallow Be-related acceptor at an energy level 0.113 eV above the VBM, corresponding to the UVLBe peak at 3.38 eV, was achieved for the first time in Be-implanted samples.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
12-9-2024
Included in
Condensed Matter Physics Commons, Electronic Devices and Semiconductor Manufacturing Commons, Engineering Physics Commons, Physical Chemistry Commons, Semiconductor and Optical Materials Commons