Woodruff School of Mechanical Engineering

NRE 8011/8012 and MP 6011/6012 Seminar

Nuclear & Radiological Engineering and Medical Physics Programs


Radiation Effects in Nanoscale-Engineered Silicon-Germanium Electronics


Dr. John D. Cressler


Georgia Tech, School of Electrical and Computer Engineering


Thursday, September 25, 2014 at 11:00:00 AM


Boggs Building, Room 3-47


Dr. Nolan Hertel


Bandgap engineering is a power tool for electronic and photonic device optimization, but until recently it has been the exclusive domain of III-V technologies such as GaAs or InP. The advent of robust epitaxial growth techniques in the silicon material system, however, is generating worldwide interest, because it enables bandgap-engineering on far-more-manufacturable silicon wafers. The most mature of the Si-based heterostructure electronic device platforms is the Silicon-Germanium Heterojunction Bipolar Transistor (SiGe HBT). At the present state-of-the-art, SiGe HBTs with frequency response above 500 GHz have been demonstrated, on CMOS foundry compatible 200 mm wafers, and is being practiced commercially around the world. The combination of ultra-high-speed SiGe HBTs with scaled silicon CMOS, to form SiGe HBT BiCMOS technology, represents a unique opportunity for highly-integrated, low-cost, silicon-based system-on-a-chip or system-in-a-package solutions for emerging high-frequency wireless and wireline applications ranging from RF as sub-mm-wave frequencies (e.g., to > 100 GHz).

Interestingly, SiGe HBTs have been shown to have a built-in tolerance to total-ionizing dose radiation, and are also well-suited for operation down to very low-temperatures (to 4.2 K), and up to very high temperatures (to 300 C), making them very appealing for a wide-variety of emerging extreme environment electronics applications, which might be needed, for instance, in space exploration.

This presentation is intended for a general audience and will focus primarily on radiation effects in SiGe HBT devices and circuits. After an introduction to bandgap engineering, SiGe strained layer epitaxy and its use in SiGe HBT design and fabrication, a detailed assessment of the impact of radiation on SiGe materials, devices, and circuits is presented, including: radiation tolerance; basic damage mechanisms; the effects of different radiation types; technology scaling issues; single event upset mitigation approaches; cryogenic operation; and the future directions of SiGe technology.


John D. Cressler received his B.S. from Georgia Tech in 1984, and his Ph.D. from Columbia University in 1990. From 1984 to 1992, he was on the research staff at the IBM Thomas J. Watson Research Center, and from 1992 to 2002 he served on the faculty at Auburn University. In 2002, he joined the faculty at Georgia Tech, and is currently Schlumberger Chair Professor of Electronics in the School of Electrical and Computer Engineering.

The basic thrust of Cressler’s research is to develop novel micro/nanoelectronic devices, circuits and systems for next-generation applications within the global electronics infrastructure. He and his team attempt to break the business-as-usual mold in this field and re-imagine the way electronics in the 21st century can and should be practiced. His research interests include: Si-based (SiGe/strained-Si) heterostructure devices and technology, mixed-signal (analog, digital, RF-sub-mmW) circuits built from these devices, radiation effects, cryogenic electronics, device-to-circuit interactions, noise and reliability physics, device-level simulation, and compact circuit modeling. He and his students have published over 600 scientific papers in this field and he has graduated 43 Ph.D. students during his academic career. He was elected Fellow of the Institute of Electrical and Electronics Engineers (IEEE) in 2001 for his research contributions, and was awarded the 2010 Class of 1940 W. Howard Ector Outstanding Teacher Award (Georgia Tech's top teaching award), the 2011 IEEE Leon Kirchmayer Graduate Teaching Award (the IEEE’s top graduate teaching award), and the Class of 1934 Distinguished Professor Award (the highest honor Georgia Tech bestows on its faculty).

Cressler’s books include: Silicon-Germanium Heterojunction Bipolar Transistors, Reinventing Teenagers: the Gentle Art of Instilling Character in Our Young People, Silicon Heterostructure Handbook, Silicon Earth: Introduction to the Microelectronics and Nanotechnology Revolution, Extreme Environment Electronics, and the historical novels Emeralds of the Alhambra and Shadows in the Shining City, love stories set in medieval Muslim Spain.