Large Signal Modelling of AlGaN/GaN HEMT for Linearity Prediction

This objective of this work is to develop predictive device modelling methodology to relate the physical behavior of AlGaN/GaN HEMTs with RF power amplifier parameters.The large signal performance of two 0.25µmx100µm GaN transistors -a standard HEMT with a recessed gate and a graded channel HEMT were analyzed at a frequency of 20 Ghz using the model.The devices are simulated in Silvaco Atlas TCAD with a velocity saturation model to obtain the high frequency two port network parameters.From these, the small signal circuit components of the device were extracted as a function of gate voltage, drain voltage and frequency.Harmonic balance simulations were performed in ADS to obtain the output power and linearity characteristics.The choice of bias points to maximize linearity from the device was explored.First and foremost, I thank Prof. Siddharth Rajan, my advisor, through whose association over the last two years, the foundation of my understanding and interest in semiconductor devices has been laid.Prof. Rajan's courses were some of the most challenging ones and motivated me to try and understand devices from an intuitive physical perspective rather than a mathematical one.I am grateful to him for having conceived the idea behind my work, his constant support, enthusiastic outlook on research and valuable guidance and suggestions regarding my projects.I thank Prof. Wu Lu for his time and suggestions during my thesis defense.I thank the members of Rajan lab -Omor Shoron, for having provided me with the Silvaco Atlas Modelling he had done for AlGaN/GaN HEMTs, Pil Sung park for having developed the velocity saturation model that is incorporated in my TCAD code, Sanyam Bajaj for his help on using Silvaco and BandEng and Sriram Krishnamoorthy, for having clarified a multitude of my doubts about Masters in Ohio State, research and device physics and for the fun music jamming sessions.I thank Prof. Waleed Khalil, for the rigorous RFIC and Analog IC coursework, which has been invaluable and given me much exposure to circuit design.I thank Satheesh for being the go-to person for me in Ohio State, for any questions starting from grocery shopping to using spectrum analyzers.I am grateful for all his help in my coursework and everything else.I thank Dipti and Mehul for being the most cooperative roommates for the last two years.I thank my parents, without whose unconditional love, support and sacrifices, I would not be here.I am indebted to them for any tiny steps I take towards achieving my goals and for always believing in