Drain current enhancement and negligible current collapse in GaN MOSFETs with atomic-layer-deposited HfO2 as a gate dielectric |
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Authors: | Y.C. Chang Y.H. Chang Y.S. Lin J.M. Hong M. Hong |
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Affiliation: | a Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan b Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan c Department of Electronics Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan d HUGA Optotech Inc., Taichung 40768, Taiwan |
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Abstract: | Accumulation-type GaN metal-oxide-semiconductor field-effect-transistors (MOSFET’s) with atomic-layer-deposited HfO2 gate dielectrics have been fabricated; a 4 μm gate-length device with a gate dielectric of 14.8 nm in thickness (an equivalent SiO2 thickness of 3.8 nm) gave a drain current of 230 mA/mm and a broad maximum transconductance of 31 mS/mm. Owing to a low interfacial density of states (Dit) at the HfO2/GaN interface, more than two third of the drain currents come from accumulation, in contrast to those of Schottky-gate GaN devices. The device also showed negligible current collapse in a wide range of bias voltages, again due to the low Dit, which effectively passivate the surface states located in the gate-drain access region. Moreover, the device demonstrated a larger forward gate bias of +6 V with a much lower gate leakage current. |
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Keywords: | GaN Metal-oxide-semiconductor field-effect-transistor (MOSFET) Current collapse HfO2 Atomic layer deposition (ALD) |
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