Demonstration of N-Polar All-AlGaN High Electron Mobility Transistors With 375 mA/mm Drive Current
Maliha Noshin, Rohith Soman, Srabanti Chowdhury
Abstract
Devices made from ultrawide bandgap (UWBG) materials are being widely investigated for high-power and radio frequency (RF) electronics. High electron mobility transistor (HEMT) is one of the most effective designs to implement heterostructures in III-Nitrides and III-Oxides that leverage a 2D-channel with high conductivity and large breakdown electric field. Nitrogen (N)-polarity in GaN channel HEMTs have shown remarkable performance advantage in both power and RF applications compared to its metal-polar counterpart. Here, UWBG N-polar AlGaN channel HEMT can bring further performance benefits due to an increase in the channel’s breakdown electric field. In this work, we report the first experimental demonstration of N-polar all-AlGaN HEMT devices with two different Al compositions (20% and 30%) in the channel. The HEMT with 3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> long-channel (20% Al) showed a drive current of 375 mA/mm (at 0 V gate voltage). These devices also show low on-state leakage current of ~0.5 nA/mm, and large on/off ratio of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 2\times 10^{{8}}$ </tex-math></inline-formula> . Furthermore, > 400 V breakdown voltage was achieved without any field plate structures.