Advisor: Paul R. Berger
Ms. Parastou Fakhimi (ECE undergrad researcher to Masters)
Lee Mosbacker (Traycer Diagnostics)
Roger Loo (IMEC)
Ngoc Duy Nguyen (IMEC)
Shotaro Takeuchi (formerly IMEC)
Matty Caymax (IMEC)
Phillip E. Thompson (Naval Research Laboratory)
Patrick J. Fay (University of Notre Dame)
Charles L. A. Cerny (AFRL-WPAFB)
Joseph E. Van Nostrand, (AFRL-WPAFB)
Former Graduate Students:
Ms. Anisha Ramesh (ECE Ph.D. 2012)
Si-Young Park (ECE Ph.D. 2009)
Sung-Yong Chung (ECE Ph.D. 2005)
Niu Jin (Ph.D. 2004)
This project demonstrates Si-based sensors with high room temperature curvature coefficient which is suitable for seamless integration with Si readout circuitry for passive millimeter-wave detection of reflected RF energy for detection of concealed weapons and pilot assistance through rain, fog and smoke. Highest reported zero-bias curvature coefficient of any Si-based backward diode (2-fold increase). A high nonlinearity directly correlates to high sensitivity for a passive millimeter-wave camera system suitable for detection of concealed weapons and vision through fog, smoke and other obscuring media for transportation safety.
High sensitivity Si-based backward diodes were realized that are monolithically integratable with transistor circuitry. Potential applications include large area focal plane arrays. The Si-based backward diodes exhibit a high zero-biased curvature coefficient, g, of 31 V-1 and a low zero biased junction capacitance, Cj, of 9 fF/m2, all at room temperature. The predicted low frequency voltage sensitivity, bv, for a 50 W source is 3100 V/W. The high sensitivity, low junction capacitance, and Si/SiGe heterojunction bipolar transistor (HBT) compatibility of the Si-based backward diodes make them very attractive for zero-bias square-law detector applications.
Silicon-based backward diodes incorporating delta-doped active regions for direct detection of microwave radiation with zero external dc bias was demonstrated at room temperature and sensitivity characterized. The resulting backward diodes, which were grown by low temperature molecular beam epitaxy, show a high zero-bias curvature coefficient ( ) of 23.2 V-1 with a junction resistance (Rj) of 687 kohm for a 5 micron diameter diode. The microwave-frequency voltage sensitivity is reported for the first time; a measured sensitivity of 2376 V/W is obtained at zero-bias. An intrinsic 3-dB cutoff frequency of 1.8 GHz was determined based on an extracted series resistance of 290 ohm and a junction capacitance of 0.307 pF using a small signal model established to fit the measured S-parameters.
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