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Investigation Of Surface States And Device Surface Charging In Nitride Materials Using Scanning Kelvin Probe Microscopy, Mohammed Shahriar Sabuktagin
Investigation Of Surface States And Device Surface Charging In Nitride Materials Using Scanning Kelvin Probe Microscopy, Mohammed Shahriar Sabuktagin
Theses and Dissertations
In this work Scanning Kelvin Probe Microscopy (SKPM) was used to characterize surface states and device surface charging in nitride materials. Samples grown by Molecular Beam Epitaxy (MBE), Metal Organic Chemical Vapor Deposition (MOCVD) and Hydride Vapor Phase Epitaxy (HVPE) typically show a high surface band bending of about 1 eV. In an n-type sample with 3X1017 cm-3 carrier concentration, 1 eV upward band bending corresponds to 1.7X1012 cm-2 trapped charge density in the surface states. Under continuous ultraviolet (UV) illumination up to 0.6 eV surface photo voltage effect could be observed in some samples, which further indicates that surface …
A Study On The Nature Of Anomalous Current Conduction In Gallium Nitride, Joshua K. Spradlin
A Study On The Nature Of Anomalous Current Conduction In Gallium Nitride, Joshua K. Spradlin
Theses and Dissertations
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 …