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Huffman, J. E.

Publications and source records attributed to Huffman, J. E..

Far-Infrared Blocked Impurity Band Detector Development

DRS Sensors & Targeting Systems, supported by detector materials supplier Lawrence Semiconductor Research Laboratory, is developing far-infrared detectors jointly with NASA Langley under the Far-IR Detector Technology Advancement Partnership (FIDTAP). The detectors are intended for spectral characterization of the Earth's energy budget from space. During the first year of this effort we have designed, fabricated, and evaluated pilot Blocked Impurity Band (BIB) detectors in both silicon and germanium, utilizing pre-existing customized detector materials and photolithographic masks. A second-year effort has prepared improved silicon materials, fabricated custom photolithographic masks for detector process, and begun detector processing. We report the characterization results from the pilot detectors and other progress.

Hogue, H. H.↗

Near-contact diffusion and compensation in extrinsic photoconductors

Carrier diffusion from heavily doped contact regions has been experimentally monitored with resistivity measurements of variable thickness Si:P extrinsic photoconductors (n(+) -n-n(+)). Modeling of free carrier diffusion at the interface of heavily doped contacts and highly resistive bulk at low temperatures predicts extended regions (5-30 microns) of excess carriers in high purity materials so that, in thin device structures, free carrier diffusion profiles from each contact will overlap and determine the resistivity of the device. In this work, a decrease in resistivity of four orders of magnitude was observed in a 5-micron thick structure compared to a 10-micron thick device. The resistivity of an ohmic structure in the thin limit is strongly dependent on the bulk and near-contact compensation, and resistivity measurements can be used as a sensitive measure of compensation at interfaces or in the tail of implanted layers.

Olsen, C. S.↗