RAMACHANDRAN , RAMYA . Investigation of Surface States in Gallium Nitride

RAMACHANDRAN, RAMYA. Investigation of Surface States in Gallium Nitride Devices using a New High Frequency Measurement Technique. (Under the direction of Dr. Douglas W. Barlage). Surface states place a limitation on the high-frequency behavior of Gallium Nitride devices by causing RF dispersion. They are also a source of undesirable 1/f noise. This thesis specifically aims to explore techniques to address known experimental observations of dispersion phenomena of unknown origin in the 1-30 GHz frequency range. A new method to investigate these at high frequencies is proposed. It involves the measurement of S-parameters between the drain and source of a GaN n-i-n structure in the GHz frequency range. The basis of the proposed technique is the assumption that the behavior of surface states and other dispersion phenomena can be isolated by subtracting the behavior of the device from the measured Y -parameters. Investigation of Surface States in Gallium Nitride Devices using a New High Frequency Measurement Technique