The semiconductor gallium arsenide (GaAs) has many potential
advantages over the more widely used semiconductor silicon (Si).
These include higher low field mobility, semi-insulating substrates,
a direct band-gap, and greater radiation hardness. All these
advantages offer distinct opportunities for implementation of new
circuit functions or extension of the operating conditions of similar
circuits in silicon based technology. However, full exploitation of
these advantages has not been realized. This study examines the
limitations imposed on conventional GaAs metal-semiconductor field
effect transistor (MESFET) technology by deviations of the semi-insulating
substrate material from ideal behavior. The interaction
of the active device with defects in the semi-insulating GaAs
substrate is examined and the resulting deviations in MESFET
performance from ideal behavior are analyzed.
A p-well MESFET technology is successfully implemented which
acts to shield the active device from defects in the substrate.
Improvements in the operating characteristics include elimination of
drain current transients with long time constants, elimination of the
frequency dependence of g[subscript ds] at low frequencies, and the elimination of
sidegating. These results demonstrate that control of the channel to
substrate junction results in a dramatic improvement in the
functionality of the GaAs MESFET. The p-well MESFET RF
characteristics are examined for different p-well doping levels.
Performance comparable with the conventional GaAs MESFET technology
is demonstrated. Results indicate that optimization of the p-well
MESFET doping levels will result in devices with uniform
characteristics from DC to the highest operating frequency. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36995 |
| Date | 02 August 1990 |
| Creators | Canfield, Philip C. |
| Contributors | Allstot, David J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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