Membrane Supported GaN CPW Structures for High-frequency and High-power Applications

• Published in: 2019 IEEE Asia-Pacific Microwave Conference (APMC) pp. 1179 - 1181
• Main Authors: Eblabla, Abdalla, Alathbah, Moath, Wu, Zehao, Lees, Jonathan, Elgaid, Khaled
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-12-2019
• Subjects: Coplanar waveguides; Gallium nitride; GaN membrane technology; GaN-based HEMTs on low-resistivity silicon; HEMTs; Millimeter-wave integrated circuits interconnect; MMIC; MODFETs; Radio frequency; Silicon; Substrates
• DOI: 10.1109/APMC46564.2019.9038731

High performance coplanar waveguides (CPWs) on GaN membrane technology for AlGaN/GaN high electron mobility transistors (HEMTs) grown on low-resistivity (LR) Si substrates have been demonstrated in this work. The developed CPW technology shows a remarkable improvement in RF losses when the lossy Si beneath CPW structures is removed, resulting in comparable RF performance to that of CPW realized on high-resistivity (HR) Si and semi-insulating (SI) SiC substrates, with similar AlGaN/GaN top epitaxial layers. Experimental results, first to be reported, demonstrate transmission losses ( S21) of 0.47 dB and Q-factor of 20.77 for the CPW on GaN membrane technology, compared to S21 of 2.95 dB and Q-factor of 4.51 for the CPW on GaN-on-LR Si, at 40 GHz. Furthermore, the influence of substrate parasitics on RF performance of CPW on GaN-based HEMTs grown on various substrates was studied and analyzed by the extraction of transmission line parameters for frequencies up to 40 GHz. These findings offer viable integrated GaN-based HEMTs on LR Si technology suitable for high-power and high-temperature system applications at RF and millimeter-wave frequencies, when used in conjunction with high thermal coefficient materials such as diamond and AIN.