Date of Award

1-1-2000

Thesis Type

Masters

Document Type

Thesis

Divisions

Faculty of Science

Department

Department of Physics

Institution

Universiti Malaya

Abstract

The n-channel enhancement mode power MOSFET device which is known to have the highest switching speed among the controllable switches group is the device studied in this research work. This commercially packaged device manufactured. by Harris Semiconductor has a combination ofMOSFET and JFET structures superimposed. It has a p-type MOS gate and a reversed biased field induced pin junction laterally at the surface and a vertical JFET structure. A Keithley 590 C-V Analyz.er was used to characterize this device. High frequency (1MHz) capacitance-voltage (C-V) and conductance-voltage (G-V) characteristic were measw-ed across the gate-source, gate-drain and source-drain tenninals of the device. These tenninaJs were biased at voltages ranging from - 7V to 7V and the remaining terminal was grounded and was used as a reference voltage. C-V and G-V curves obtained were ana1yzed and related to the structure of the device. Since the switching properties are dependent on the electrical properties across the gate-source structure, detailed measurements were concentrated across this structure. The C-V and GV measurements were done at different temperatures ranging from room temperature to 175°C. The device was annealed at different temperatures ranging from 100°C to 400°C. Since. significant effects were observed on the C-V and G-V curves of the device annealed at 400°C, similar measurements done on the device prior to annealing were repeated on the device annealed at 400°C. The C-V characteristic produced a p-type MOS characteri stic when negatively biased and an n-typc MOS characteristic when positively biased. The switching properties of a .. normally OFF" device was observed from the G-V characteristic curve. Increasing the measurement temperature resulted in the shift of the C-V and G-V curves towards zero gate voltage in both the positive and negative biased regions. These shifts produced significant effects on the peak conductance voltage, capacitance and conductance values at zero gate voltage and peak conductance value. Annealing at 400°C showed significant effects on the "tum-off"' and "tum-on" conductance value however showed almost insignificant effect on the "tum-on" voltage. These results were analyzed to provide physical explanation to the operation of the device, the tolerance of this device to extreme temperatures and device performance at temperatures above room temperatures.

Initial

snms

Additional Information

Dissertation (M.A) -- Faculty of Science, Universiti Malaya, 2000.

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