Liu, S., Zhuang, Y., Cui, P., Xie, Q., Li, H., Tan, H. T., Xie, H., Xi, L., Boothroyd, C., & Ng, G. I. (2026). Multimode GaN Transistors with Ultrawide Threshold Voltage Control Enabled by Passivation-Induced Stress–Strain–Polarization Coupling. ACS Applied Materials & Interfaces. https://doi.org/10.1021/acsami.6c08343
Abstract:
Multimode GaN transistors achieve multimodality by exploiting a broadly tunable and ultrawide threshold voltage (VTH) that covers both depletion-mode (D-mode) and enhancement-mode (E-mode) operation. This VTH tunability is enabled by epitaxial growth of ultrathin AlN barriers with high interface quality and strong electrostatic control, combined with tensile stress introduced by PECVD-SiN passivation. Through stress–strain–polarization coupling (SSPC), strain along [0001] approaching −4.2% was generated, which increased the 2DEG density by more than 1 order of magnitude and thus enabled an ultrawide VTH window. The evolution among background-carrier, MOS-like, and D/E-mode high-electron mobility transistor (HEMT) conduction modes under different passivation thickness (PT) was further clarified by simulations, accounting for the observed multimode behavior. SSPC was thus supported as a compact and low-damage method for etch-free tuning of polarization, carrier density, and VTH. The continuously tunable conduction modes provide multimode GaN transistors multiple functionalities, enabling applications in RF amplification, multimode neuromorphic computing, efficient power conversion, and complex circuit optimization.
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Funding Info:
This research / project is supported by the A*STAR - White Space Manufacturing, Trade, and Connectivity Funding
Grant Reference no. : M23WSNG001
This research / project is supported by the A*STAR - Manufacturing, Trade, and Connectivity Industry Alignment Fund Pre-Positioning (IAF-PP)
Grant Reference no. : M22L3a0112