Master of Science / Department of Electrical and Computer Engineering / William Kuhn / Studies of Silicon-on-Sapphire (SOS) CMOS device operation in cryogenic environments
are presented. The main focus was to observe the characteristic changes in high, medium and
low threshold SOS NFETs as well as SOS silicide blocked (SN) resistors when the operational
temperature is in the devices’ freeze-out range below 77 Kelvin. The measurements taken will
be useful to any integrated circuit (IC) designer creating devices based on an SOS process
intended to operate in cryogenic environments such as superconducting electronics and planetary
probes.
First, a 1N4001 rectifier and a 2N7000 NFET were tested to see how freeze-out effects
standard diode and MOS devices. These devices were tested to see if the measurement setup
could induce carrier freeze-out.
Next, SOS devices were studied. Data was collected at room temperature and as low as 5
Kelvin to observe resistance changes in an SN resistor and kink effect, threshold voltage shifts
and current level changes in transistors. A 2μm high threshold NFET was tested at room
temperature, 50 Kelvin, 30 Kelvin and 5 Kelvin to observe effects on I-V curves at different
temperatures with-in the freeze-out range. A 2μm medium threshold NFET was tested down to
56 Kelvin to see if the behavior is similar to the high threshold FET. A 2μm intrinsic, or low
threshold, NFET was also tested with the assumption it would be the most susceptible to carrier
freeze-out. All of the devices were found to behave well with only mild effects noted.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/14864 |
| Date | January 1900 |
| Creators | Melton, Steven Allen |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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