Liu, S., Zhuang, Y., Li, H., Xie, Q., Wang, Y., Xie, H., Ranjan, K., Ng, G. I. (2024). Variable range hopping-assisted parasitic channel leakage in AlN/GaN/AlGaN HEMTs on Si. Applied Physics Letters, 125(2). https://doi.org/10.1063/5.0219359
Abstract:
This work investigates the off-state leakage characteristics of AlN/GaN/AlGaN high electron mobility transistors (HEMTs) on Si substrate with varying mesa depths and uncovers the existence of a parasitic channel associated with the AlGaN back barrier. Significant differences in off-state leakage up to three orders of magnitude were observed between devices fabricated using different mesa depths. The electrical properties of AlN/GaN/AlGaN HEMTs were measured, and it was found that there is a N-type parasitic channel in the unintentionally doped AlGaN back-barrier. Analysis of the isolation test structure, which retains this parasitic channel, reveals a buffer leakage of 12.8 mA/mm and a sheet resistance of 7739.1 Ω/sq, as a result of the parasitic channel. The depletion electric field strength of the parasitic channel is 3.2 × 105 V/cm. Temperature-dependent I–V curves obtained from the isolation area affirm that the primary leakage mechanism is two-dimensional variable range hopping along the sidewall. As the isolation distance extends from 3 to 5 μm, the slope of the fitting line decreases from −53.14 to −126.11 due to increased resistance.
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Funding Info:
This research / project is supported by the NRF and A*STAR - RIE2025 MTC IAF-PP
Grant Reference no. : M22L3a0112
This research / project is supported by the NRF and A*STAR - RIE2025 White Space-MTC
Grant Reference no. : M23WSNG001
Description:
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in (Liu, S., Zhuang, Y., Li, H., Xie, Q., Wang, Y., Xie, H., Ranjan, K., & Ng, G. I. (2024). Variable range hopping-assisted parasitic channel leakage in AlN/GaN/AlGaN HEMTs on Si. Applied Physics Letters, 125(2). https://doi.org/10.1063/5.0219359) and may be found at (http://dx.doi.org/10.1063/5.0219359)