Ferroelectric‐Gated HfZrO2/AlGaN/GaN HEMTs with Regrown Contacts for RF and mm‐Wave Switch Applications

Emerging millimeter‐wave wireless communication systems require high‐performance radio frequency (RF) switches to support advanced functionality such as frequency agility, circuit reconfigurability, and beamforming. Ferroelectric‐gated AlGaN/GaN HEMTs (FeHEMTs) have been developed and demonstrated as a technology option for this important role. AlGaN/GaN HEMT heterostructures grown by MOCVD have been augmented with a ferroelectric gate stack comprising ALD‐grown HfZrO 2 . In addition, highly doped regrown source and drain ohmic contacts have been integrated into an improved fabrication process flow. This improved process leads to contact resistances of 0.105 Ω‐mm and a reduction in switch on‐resistance of approximately 30% compared to prior reports, as well as drain current densities of 1 A/mm and measured f t =54 GHz for gate lengths of 0.1 µm. The improved contact and gate length scaling makes FeHEMTs a promising candidate for mm‐wave switch applications with a reported switch figure of merit of f CO = 1.55 THz. This article is protected by copyright. All rights reserved.