AFM and C-AFM Studies of GaN Films

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 samples with low leakage were usually grown at moderate temperatures (~650°C). For such samples, localized leakage only occurred at screw dislocations located at small pits terminating surface hillocks. I-V spectra taken on and off such hillocks were fit in forward bias to determine whether field emission or Frenkel-Poole conduction were dominant. Although field emission is a good fit compared to Frenkel-Poole, yielding reasonable values for the barrier height, the results are not yet conclusive without variable temperature studies.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Physics

Year dc:date.available

2005

Author dc:creator

• Cooper, Katherine

Contributors dc:contributor

• Dr. Alison Baski

• spectra
• GaN films
• AFM
• Physical Sciences and Mathematics
• Physics

Statement dc:rights

• © The Author

Identifier

https://scholarscompass.vcu.edu/etd/1246

OAI identifier oai:identifier

oai:scholarscompass.vcu.edu:etd-2245