Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Alison Baski


This thesis discusses a variety of techniques based on the atomic force microscope (AFM), and their application to the GaN materials system. In particular, the local conductivity and contact potential of surfaces have been measured using the techniques of Conductive AFM (CAFM) and Surface Potential Electric Force Microscopy (SPEFM), respectively. CAFM studies of GaN surfaces have revealed that prismatic planes around islands and pits on surfaces can lead to enhanced conductivity, which may be related to leakage problems in device applications. With regard to SP-EFM work, the change in surface potential associated with inversion domains on Ga-polar GaN has been imaged, yielding voltage differences up to 90 mV. Given that such inversion domains increase carrier scattering and can degrade device performance, their identification using this technique is important. SP-EFM has also been used to map the local surface potential in the active region of Modulation Doped Field Effect Transistors (MODFET's). This is the first step in a proposed study to investigate the effects of current lag in such devices.


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