High Performance Gallium Nitride (GaN) Transistor Design

The use of GaN as a semiconductor in transistors has, for many reasons, recently become a promising area of research. GaN has a relatively high band-gap of 3.4 eV allowing it to have a high breakdown voltage, have promising optical applications such as LEDs, and operate at high temperatures. A GaN/AlGaN heterojunction takes advantage of GaN polarization effects to establish a two-dimensional electron gas (2DEG) above this junction without any doping, which other semiconductors need in order to create such a quantum well. The 2DEG allows GaN transistors to operate at high speeds and efficiencies. It is also important to mention that trends in electron velocity and mobility verses device size suggest that smaller devices will run faster. Furthermore, a Nitrogen polar configuration, where the 2DEG is above the AlGaN barrier layer, allows for scaling down the gate length while maintaining high aspect ratio, which determines the ability of the gate to control the channel. Our research aims to take advantage of these properties by implementing a unique self aligned gate design which results in a small gate as well as highly doped, low resistance source and drain contacts in order to create small, fast, and durable transistors.