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Virginia Commonwealth University

Theses and Dissertations

Semiconductor

Publication Year

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Full-Text Articles in Physics

Cafm Studies Of Epitaxial Lateral Overgrowth Gan Films, Vishal P. Kasliwal Jan 2007

Cafm Studies Of Epitaxial Lateral Overgrowth Gan Films, Vishal P. Kasliwal

Theses and Dissertations

This thesis uses the techniques of atomic force microscopy (AFM) and conductiveAFM (CAFM) to study defect sites on GaN films. In particular, these defect sites demonstrate current leakage under reverse-bias conditions that are detrimental to device fabrication. Two growth techniques that were used to improve this leakage behavior for samples in this study included: epitaxial lateral overgrowth (ELO) and nano-ELO using a Si3N4 film. Both techniques decrease defects such as threading dislocations by controlling the nucleation and growth behavior of the GaN films. The EL0 technique uses a patterned dielectric film to laterally grow micron-wide regions (referred to as 'wings') …


Raman Scattering In Gan And Zno, Shinobu Nagata Jan 2007

Raman Scattering In Gan And Zno, Shinobu Nagata

Theses and Dissertations

The Micro-Raman scattering technique has been used for the study of GaN and ZnO. Capabilities of the Raman technique and existing literature on Raman spectroscopy in GaN and ZnO are reviewed. About 50 GaN and ZnO samples with a wide range of properties are studied. From the analysis of positions of the E2H and A1(LO) phonon modes, biaxial stress and plasmon coupling of the Al(LO) mode are observed and compared to a bulk GaN sample. The stress-related shift rate for the AI(LO) mode in hexagonal GaN is established to be 2.7 ± 0.4 cm-1/GPa through series of GaN with low …


Stm Studies Of Oxygen Etching Of Silicon Surfaces, Mary L. Willis Jan 2005

Stm Studies Of Oxygen Etching Of Silicon Surfaces, Mary L. Willis

Theses and Dissertations

This study uses atomic force microscopy (AFM) to investigate the oxygen etching behavior of the following silicon surface orientations: (001), (111), (113), (5 5 12) and (112). Most etching was performed at sample temperatures between 650 °C and 800 °C, at pressures of 3.3×10-7 and 1.5×10-7 Torr, and at an exposure of 200 L. Surface orientation strongly influences the morphology resulting from extended etching. The surface orientations that are stable against etching and remain flat include Si(001), Si(111), and Si(113). Such surfaces also include island structures, which result from etching around oxide-induced pinning sites. The density of these islands increases …