GAN-ON- SI(100) NANOSTRUCTURES FOR OPTOELECTRONICS APPLICATIONS

This thesis focused on the development of high quality GaN epilayers for optoelectronics applications. GaN based materials were grown on Si(100) substrates by modifying the surface of the Si(100) substrate to expose the Si(111) planes . The Si(100) plane has a four-fold (square) atomic symmetry while the Si(111) possess a three-fold (triangle) atomic symmetry. The three-fold atomic symmetry of the Si(111) plane is more suitable as template for the deposition of GaN which has six-fold (hexagon) atomic symmetry. Anisotropically etched-holes with Si(111) sidewalls arranged in a triangular-array was found to be desirable to obtain continuous GaN epilayer films. The presence of vicinal surface on the exposed Si(111) planes resulted in two phenomenon; firstly, is the crystallographic tilt of the GaN(0002) plane relative to the Si(111) plane and secondly, the reduction of dislocations density by two orders of magnitude via the bending of the dislocation by 3D AlN buffer islands.

Author dc:creator

• KWADWO KONADU ANSAH-ANTWI

• GaN, Heteroepitaxy, Surface modification, Anisotropic etching, Dislocations, Crystallographic tilt