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Full-Text Articles in Physics
Afm And C-Afm Studies Of Gan Films, Katherine Cooper
Afm And C-Afm Studies Of Gan Films, Katherine Cooper
Theses and Dissertations
This thesis uses the techniques of atomic force microscope (AFM) and conductive AFM (C-AFM) to study the conduction properties of n-type GaN films. A total of 16 samples were examined and grouped according to their surface morphologies and conduction behaviors. The most common type of surface morpliology was that of Ga-rich samples having undulating "hillocks" with interspersed holes. Although most of the samples had this common morphology, their local conduction behaviors were not all similar. Local I-V spectra of the tip-sample Schottky contact could be grouped according to three major types: low leakage, high leakage, and "p-type". The highest quality …
Integration Of Vmc++ Into A Commercial Treatment Planning System, Joseph Kingsley Gardner
Integration Of Vmc++ Into A Commercial Treatment Planning System, Joseph Kingsley Gardner
Theses and Dissertations
Recently, there has been interest to integrate VMC++ into the commercial treatment planning system at VCU as another Monte Carlo code option, since it has been shown to increase efficiency dramatically without introducing a significant amount of systematic error. Also, independent validation of VMC++ for photon beams is of interest since this has not been performed previously in literature. This study included several tests required to integrate VMC++. Output factor normalization was performed and found to agree with experiment to within 1% for all field sizes except 1x1 cm2. Geometric validation was successful. Dosimetric validation was performed with respect to …
Stm Studies Of Oxygen Etching Of Silicon Surfaces, Mary L. Willis
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 …