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Full-Text Articles in Nanoscience and Nanotechnology
Investigation Of Surface Properties For Ga- And N-Polar Gan Using Scanning Probe Microscopy Techniques, Josephus Daniel Ferguson Iii
Investigation Of Surface Properties For Ga- And N-Polar Gan Using Scanning Probe Microscopy Techniques, Josephus Daniel Ferguson Iii
Theses and Dissertations
Because the surface plays an important role in the electrical and optical properties of GaN devices, an improved understanding of surface effects should help optimize device performance. In this work, atomic force microscopy (AFM) and related techniques have been used to characterize three unique sets of n-type GaN samples. The sample sets comprised freestanding bulk GaN with Ga polar and N polar surfaces, epitaxial GaN films with laterally patterned Ga- and N-polar regions on a common surface, and truncated, hexagonal GaN microstructures containing Ga-polar mesas and semipolar facets. Morphology studies revealed that bulk Ga-polar surfaces treated with a chemical-mechanical polish …
Investigation Of Band Bending In N- And P-Type Gan, Michael Foussekis
Investigation Of Band Bending In N- And P-Type Gan, Michael Foussekis
Theses and Dissertations
This dissertation details the study of band bending in n- and p-type GaN samples with a Kelvin probe utilizing different illumination geometries, ambients (air, oxygen, vacuum 10-6 mbar), and sample temperatures (77 – 650 K). The Kelvin probe, which is mounted inside an optical cryostat, is used to measure the surface potential. Illumination of the GaN surface with band-to-band light generates electron-hole pairs, which quickly separate in the depletion region due to a strong electric field caused by the near-surface band bending. The charge that is swept to the surface reduces the band bending and generates a surface photovoltage (SPV). …