Development and Modelling of Gallium Nitride Based Lateral Schottky Barrier Diodes with Anode Recesses for mmWave and THz Applications

Abstract

This paper presents novel multi-channel RF lateral Schottky-barrier diodes (SBDs) based on AlGaN/GaN on low resistivity (LR) (σ = 0.02 Q·cm) silicon substrates. The developed technology offers a reduction of 37% in onset voltage, VON (from 1.34 to 0.84 V), and 36% in ON-resistance, RON (1.52 to 0.97 to Ω·mm), as a result of lowering the Schottky barrier height, Φn, when compared to conventional lateral SBDs. No compromise in reverse-breakdown voltage or reverse-bias leakage current performance was observed as both multi-channel and conventional technologies exhibited a VBV of (VBV > 30 V) and an IR of (IR < 38 μA/mm), respectively. Furthermore, a precise small-signal equivalent circuit model was developed and verified for frequencies up to 110 GHz. The fabricated devices exhibited cut-off frequencies of up to 0.6 THz, demonstrating the potential use of lateral AlGaN/GaN SBDs on LR silicon for high-efficiency, high-frequency integrated circuits’ applications. The paper begins with a brief outline of the basic Schottky-contact diode operation. A series resistance analysis of the diode studied in this project is discussed. The small signal equivalent circuit of the Schottky-contact diode is presented. The layout of the diodes studied is described, and their fabrication techniques are briefly mentioned. DC, RF, and low frequency C-V measurement techniques and measurements to characterize the diodes are outlined. Finally, results and discussions on the effects of multiple recesses under the Schottky-contact (anode) obtained from the I-V diode characteristics and C-V measurements, and the small signal equivalent circuit deduced from RF measurements for different diode configurations, are presented.