DOI
https://doi.org/10.25772/JQK5-HA92
Defense Date
2009
Document Type
Thesis
Degree Name
Master of Science
Department
Physics
First Advisor
Alison Baski
Second Advisor
Mikhail Reshchikov
Third Advisor
Hadis Morkoc
Abstract
Steady-state and transient surface photovoltages in undoped GaN are studied in various environments (air, nitrogen, oxygen, vacuum) at room temperature and 400 K with a Kelvin probe attached to an optical cryostat. The results are explained within a phenomenological model accounting for the accumulation of photo-generated holes at the surface, capture of free electrons from the bulk over the near-surface potential barrier, and emission of electrons from surface states into the bulk. Mechanisms of surface photovoltage are discussed in detail. Photoadsorption and photodesorption of negatively charged species will either increase or decrease the surface potential and thus band bending. Oxygen is the assumed species responsible for the SPV changes in air ambient during continuous UV illumination. This variation in SPV will be confirmed with photoluminescence measurements.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
May 2009