Characterization of GaN-based HEMT structures for high power applications

• Main Author: Pang, Shi Xiang.
• Other Authors: K Radhakrishnan
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Microelectronics
• Online Access: http://hdl.handle.net/10356/54247
• Institution: Nanyang Technological University

GaN based HEMT devices on 4 inch Si (111) were characterized to study their electrical parameters, using Hall Effect, Current-Voltage and Capacitance-Voltage measurements. Four different types of structure configurations were studied, which include different stress mitigating layers with carbon doping of the GaN buffer. The effect of carbon doping on the electrical parameters and the buffer leakage current were analyzed. The threshold voltages and the doping concentration were comprehensively studied to determine the background carrier concentration. The stress mitigating layers help to reduce cracks on the GaN layers during growth as well as allowing thicker GaN layer to be grown. Electrical parameters obtained from the characterization techniques concluded that the addition of carbon doping has proven to be effective in the reduction of both vertical and horizontal leakage currents on the GaN-HEMTs devices. The carbon doping reduces the background carrier concentrations by compensating the excessive unintentionally doped electrons in GaN buffer layers Study of Reflection High Energy Electron Diffraction (RHEED) technique was done theoretically with the discussion of diffraction theories and the usage of reciprocal space notation, and construction of Ewald’s sphere to predict diffraction patterns. Both streaky and spotty RHEED patterns obtained during GaN growth were discussed briefly.