Design of insulator/AlGaN structures in MIS AlGaN/GaN HFETs for higher device performance

Narihiko Maeda; Masanobu Hiroki; Takatomo Enoki; Takashi Kobayashi

doi:10.1117/12.808816

16 February 2009 Design of insulator/AlGaN structures in MIS AlGaN/GaN HFETs for higher device performance

Narihiko Maeda, Masanobu Hiroki, Takatomo Enoki, Takashi Kobayashi

Proceedings Volume 7216, Gallium Nitride Materials and Devices IV; 721605 (2009) https://doi.org/10.1117/12.808816
Event: SPIE OPTO: Integrated Optoelectronic Devices, 2009, San Jose, California, United States

Abstract

To improve the device performance of GaN-based Metal-Insulator-Semiconductor (MIS) heterostructure field-effect transistors (HFETs), the layer design of MIS AlGaN/GaN HFETs has been investigated by considering the insulator/AlGaN structures as the total barrier layers of MIS HFETs. Since deposition of insulators on AlGaN has proven to change electrical properties of the heterostructures as the increase in AlGaN thickness does, considering the insulator/AlGaN structures as the total barrier layers is effective and indispensable in designing the MIS AlGaN/GaN HFETs. With an increased insulator thickness and decreased AlGaN thickness, where the gate capacitance is kept constant, a high transconductance was successfully obtained that was equivalent to that of HFET, in addition to the reduced gate leakage current in MIS HFETs. Moreover, Al₂O₃-based MIS HFETs were revealed to exhibit superior DC characteristics over conventional Si₃N₄MIS HFETs, which can be ascribed to larger bandgap energy of Al₂O₃ than Si₃N₄. Channel doping design has also been proposed to incorporate into MIS HFETs to modulate the threshold voltage aiming at the same application of depression mode as conventional HFETs. In a MIS HFET with channel doping design, a significantly reduced gate leakage current was obtained with a transconductance and threshold voltage that are kept close to typical values of HFETs, indicating that the device has a potential to replace conventional HFETs. Thus, design of insulator/AlGaN structures and incorporation of channel doping design are the key, with which MIS HFETs exhibiting a low gate leakage current and high transconductance with a desired threshold voltage can be realized.

Citation Download Citation

Narihiko Maeda, Masanobu Hiroki, Takatomo Enoki, and Takashi Kobayashi "Design of insulator/AlGaN structures in MIS AlGaN/GaN HFETs for higher device performance", Proc. SPIE 7216, Gallium Nitride Materials and Devices IV, 721605 (16 February 2009); https://doi.org/10.1117/12.808816

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