Dr Lok Yi Lee

My PhD project at the Cambridge Centre for Gallium Nitride was on the growth of GaN on novel Si-based substrates.

Cubic zincblende GaN has advantages over more commonly used hexagonal wurtzite GaN, such as absence of strong internal fields and smaller band gap, which are both beneficial to the production of efficient green-wavelength LEDs. Challenges arise during growth as zincblende GaN is a metastable phase, and growth of wurtzite GaN is thermodynamically preferred. The aim of the project was to grow high quality zincblende GaN on 3C-SiC/Si substrates. To achieve this aim, I studied how parameters of the MOVPE reactor affect the surface morphology of zincblende GaN epilayers by atomic force microscopy (AFM), and defects in such epilayers by transmission electron microscopy (TEM).