Importance of Scaling in RF GaN HEMTs for Reduction of Surface Traps-Induced Drain Lag
H. Yazdania, C. Zervosb, P. Beleniotisb, E. Brusaterraa, O. Hilta, M. Rudolpha,b, and J. Würfla
Published in:
phys. stat. sol. (a), vol. 222, no. 8, pp. 2300885, doi:10.1002/pssa.202300885 (2025).
Abstract:
Drain lag is a well-known phenomenon that leads to radio frequency performance degradation in AlGaN/GaN high-electron-mobility transistors. Herein, it is demonstrated that a reduction of the gate-to-drain distance (Lgd) from 2.0 to 0.5 μm results in 7% reduction in the current collapse. This improvement is attributed to a decrease in surface trapping, which, in this case, is found to have a greater impact on current collapse than relatively slow traps in the buffer layer. To support this argument, TCAD simulations are conducted. Load-pull analysis confirms that scaling the devices to Lgd = 0.5 μm provides 15% better output power density at 10 GHz than Lgd = 2.0&nbp;μm. Additionally, a new passivation layer for reduced surface traps exhibits a 20 to 30% higher output power density and at least a 10% improvement in power-added efficiency at 20 GHz on a nominally identical GaN-on-semi-insulating SiC epi-wafer.
aFerdinand-Braun-Institut gGmbH Leibniz-Institut für Höchstfrequenztechnik (FBH), Berlin 12489, Germany
bChair of Radio Frequency and Microwave Techniques Brandenburg University of Technology (BTU), Cottbus 03013, Germany
Keywords:
drain lags, GaN HEMTs, two-dimensional electrons gas
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