[CCoE Notice] Thesis Defense: X-Ray Techniques for GaN Characterization

[Grayson, Audrey A]

Weijie Wang’s M.S. Defense Announcement
X-Ray Techniques for GaN Characterization

Date:  06/22/2015 (Mon)
Time:  10:30 am ~ 12:30 pm
Location:  Mechanical Engineering Department small conference room (ENG 1, #208)

Committee Chair: Dr Jae-Hyun Ryou
Committee members: Dr Li Sun and Dr Jiming Bao

Abstract
Gallium nitride (Ga<https://en.wikipedia.org/wiki/Gallium>N<https://en.wikipedia.org/wiki/Nitrogen>) is a binary III<https://en.wikipedia.org/wiki/Boron_group>/V<https://en.wikipedia.org/wiki/Nitrogen_group> direct bandgap<https://en.wikipedia.org/wiki/Direct_bandgap> semiconductor<https://en.wikipedia.org/wiki/Semiconductor>. In recent years, due to unique characteristics like wide bandgap, large breakdown field strength, superior carrier saturation velocity, high heat capacity, and thermal conductivity, GaN is widely applied in light emitting diodes, optoelectronics, high-power and high frequency electronic devices.
However, a large difference in the coefficient of thermal expansion and lattice constant between GaN epitaxial layer and the substrate exists. These thermal mismatch and lattice mismatch lead to strain and the generation of defects in the GaN, affecting the performance of the devices.
In this dissertation, techniques of X-ray diffraction are applied for characterization: reciprocal space mapping is applied to analyze strain and relaxation in epitaxial layers; high-resolution rocking curves are applied for dislocation density calculation; and X-ray reflectivity is applied to characterize the thickness and roughness.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://Bug.EGR.UH.EDU/pipermail/engi-dist/attachments/20150618/2a9b2433/attachment-0001.html