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Browsing by Author "Chang, E. Y."

Now showing 1 - 4 of 4
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    Cascode GaN HEMT Gate Driving Analysis
    Heumesser, V.; Lai, J. S.; Hsieh, H. C.; Hsu, J.; Yang, C. Y.; Chang, E. Y.; Liu, C. Y.; Chieng, W. H.; Hsieh, Y. T. (IEEE, 2023-01-01)
    The aim of this paper is to analyze the conventional cascode gate driving to understand the switching transition and to provide a design guide for the GaN HEMT and its associated packaging. A double-pulse tester has been designed and fabricated with minimum parasitic inductance to avoid unnecessary parasitic ringing. The switching behaviors in both turn-on and -off are analyzed through topological study and explained through SPICE simulation. Two different cascode devices were tested to show the impact of threshold voltage and low-voltage Si MOSFET selection.
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    D-Mode GaN HEMT with Direct Drive
    Heumesser, V.; Lai, J. S.; Hsieh, H. C.; Hsu, J.; Yang, C. Y.; Chang, E. Y.; Ko, H. K.; Liu, W. H.; Lin, Y. M. (IEEE, 2023-01-01)
    A direct-driven gate driver circuit has been developed for the depletion-mode gallium nitride (d-mode GaN) high electron mobility transistor (HEMT), which is a'normally on'' device and is typically connected in series with a low-voltage power MOSFET to prevent shoot-through faults. The switching of such a''cascode'' device is substantially delayed due to a large MOSFET input capacitance. This paper introduces a charge-pump based direct-driven approach to provide a negative voltage in the gate drive loop so that the device becomes 'normally off The switching characteristics of the direct-driven HEMT is analyzed through computer simulation and hardware testing. Results indicate that the switching delays due to MOSFET gating is eliminated, and the voltage slew rate can be directly controlled by the gate resistance.
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    High quality Ge thin film grown by ultrahigh vacuum chemical vapor deposition on GaAs substrate
    Tang, S. H.; Chang, E. Y.; Hudait, Mantu K.; Maa, J. S.; Liu, C. W.; Luo, G. L.; Trinh, H. D.; Su, Y. H. (AIP Publishing, 2011-04-01)
    High-quality epitaxial Ge films were grown on GaAs substrates by ultrahigh vacuum chemical vapor deposition. High crystallinity and smooth surface were observed for these films by x-ray diffraction, transmission electron microscopy, and atomic force microscopy. Direct band gap emission (1550 nm) from this structure was detected by photoluminescence. Valence band offset of 0.16 eV at the Ge/GaAs interface was measured by x-ray photoelectron spectroscopy. N-type arsenic self-doping of 10(18)/cm(-3) in the grown Ge layers was determined using electrochemical capacitance voltage measurement. This structure can be used to fabricate p-channel metal-oxide-semiconductor field-effect transistor for the integration of Ge p-channel device with GaAs n-channel electronic device. (C) 2011 American Institute of Physics. [doi:10.1063/1.3580605]
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    The influences of surface treatment and gas annealing conditions on the inversion behaviors of the atomic-layer-deposition Al2O3/n-In0.53Ga0.47As metal-oxide-semiconductor capacitor
    Trinh, H. D.; Chang, E. Y.; Wu, P. W.; Wong, Y. Y.; Chang, C. T.; Hsieh, Y. F.; Yu, C. C.; Nguyen, H. Q.; Lin, Y. C.; Lin, K. L.; Hudait, Mantu K. (AIP Publishing, 2010-07-01)
    The inversion behaviors of atomic-layer-deposition Al2O3/n-In0.53Ga0.47As metal-oxide-semiconductor capacitors are studied by various surface treatments and postdeposition annealing using different gases. By using the combination of wet sulfide and dry trimethyl aluminum surface treatment along with pure hydrogen annealing, a strong inversion capacitance-voltage (C-V) response is observed, indicating a remarkable reduction in interface trap state density (D-it) at lower half-part of In0.53Ga0.47As band gap. This low D-it was confirmed by the temperature independent C-V stretch-out and horizontal C-V curves. The x-ray photoelectron spectroscopy spectra further confirm the effectiveness of hydrogen annealing on the reduction of native oxides. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467813]