AlGaN/GaN schottky barrier diode technology for RF application

Wu, Zehao 2025. AlGaN/GaN schottky barrier diode technology for RF application. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

This thesis investigates AlGaN/GaN Schottky diodes on Si for Ka-band (26.5– 40 GHz) nonlinear front-ends. Device-level performance is governed by series/on resistance (Rs/Ron), junction capacitance (Cj), and cut-off frequency (fc). Diodes with 2-/4-finger anodes were fabricated on high- and low-resistivity Si; small-signal parameters were extracted from 100 MHz–50 GHz S-parameters using open/short de-embedding. Representative devices exhibit Cj ≈ 15 fF at 0 V for a 2-finger high-resistivity sample, falling to ≈ 6.9 fF at −10 V (~54% reduction). For a 25-nm/20%-Al barrier variant, fc reaches ~163 GHz, providing ample Ka-band margin. Across 26.5–40 GHz, reverse bias consistently improves S11; under −10 V the high-resistivity substrate yields the best overall reflection. Extracted Rs spans ~46–102 Ω depending on layout and epilayer. These results demonstrate the suitability of the reported process and geometries for Ka-band mixers/multipliers and motivate leveraging reverse bias to trade Cj against impedance matching in circuit design.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Engineering
Date of First Compliant Deposit:	12 December 2025
Last Modified:	12 Dec 2025 11:22
URI:	https://orca.cardiff.ac.uk/id/eprint/183168

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