A Study on the Nature of Anomalous Current Conduction in Gallium Nitride

• Main Author: Spradlin, Joshua K.
• Format: Others
• Published: VCU Scholars Compass 2005
• Subjects: photoluminescence; SEM; DLTS; CAFM; mobility; KOH etching; MODFET; resistivity; III-Nitride; III-V; Hall measurements; silvaco; schottky diode; illumination; polarization; MBE; MOCVD; HVPE; semiconductor; Electrical and Computer Engineering; Engineering
• Online Access: http://scholarscompass.vcu.edu/etd/709; http://scholarscompass.vcu.edu/cgi/viewcontent.cgi?article=1708&context=etd

Current leakage in GaN thin films limits reliable device fabrication. A variety of Ga and N rich MBE GaN thin films grown by Rf, NH3, and Rf+ NH3, are examined with electrical measurements on NiIAu Schottky diodes and CAFM. Current-voltage (IV) mechanisms will identify conduction mechanisms on diodes, and CAFM measurements will investigate the microstructure of conduction in GaN thin films. With CAFM, enhanced conduction has been shown to decorate some extended defects and surface features, while CAFM spectroscopy on a MODFET structure indicates a correlation between extended defects and field conduction behavior at room temperature. A remedy for poor conduction characteristics is presented in molten KOH etching, as evidenced by CAFM measurements, Schottky diodes, and MODFET's. The aim of this study is to identify anomalous conduction mechanisms, the likely cause of anomalous conduction, and a method for improving the conduction characteristics. Keywords: 111-Nitride, 111-V, Gallium Nitride, GaN, Electrical Properties, Conduction, Conductivity, Mobility, Hall Measurements, Resistivity, Schottky Diode, Modulation Doped Field Effect Transistor (MODFET), Conductive Atomic Force Microscopy (AFM), Defects, Molten Potassium Hydroxide (KOH) etching, Silvaco, Atlas, and Illumination.