University of Illinois at Urbana-Champaign
The invention of transistor by Bardeen and Brattain in 1947 lead us to realize that the ‘magic” of the transistor is intrinsically in the base. And, it is the base that potentially offers more, particularly when we arrive at the direct-gap, high speed, high current density heterojunction bipolar transistor (HBT) and realize the base although thin (10-100nm), has room for more layering (bandgap and doping) and can be modified.
Employing quantum-wells (QWs) and cavity reflection, we can re-invent the base region and its mechanics (its carrier recombination and transport fraction), reduce the current gain and achieve stimulated recombination, i.e., realize a transistor laser – a novel device with an electrical input, an electrical output and an optical output. The result is unique transistor in form and operation, as well as a unique three-terminal laser. Much more structure is evident in the output collector current and voltage characteristics owing to the sensitivity to QW bandfilling, state change, spectral change, mode hopping, change in optical field strength, and the effect of photon-assisted collector tunneling. We note that quantum well base region and stimulated recombination (stimulated emission), besides yielding a transistor laser, changes the transistor into an active element that can used for nonlinear and switching applications (both electrical and optical) as we recently demonstrated. With two electrical inputs through the base, we demonstrated new mixer with both electrical and optical outputs in nonlinear operation region and signals addition to produce new waveform in linear operation region. High Speed direct modulation of clear eye-diagram @ 20 Gbit/s has been demonstrated. It is an amazing new device opens up new optoelectronics integration frontier.
Since 1991, Dr. Feng has been a professor of electrical and computer engineering and a research professor at the Microelectronics Laboratory at the University of Illinois. Prof. Feng invented the pseudomorphic HBT (PHBT), “pushed” the transistor speed boundary toward THz, and demonstrated InP PHBTs with the world’s fastest speed performance (> 800 GHz). Prof. Feng, along with Prof. N. Holonyak, Jr., demonstrated the first laser operation of a quantum-well-based light emitting transistor (QWLET), a transistor laser (TL). A transistor laser opens up a rich domain of integrated circuitry and high speed signal processing that involves both electrical and optical signals.
Prof. Feng has published over 200 papers, 200 conference talks, and been granted 25 U.S. patents in semiconductor microelectronics. He is an IEEE and OSA Fellow, and serves on many executive and strategy committees both in industry and at conferences. In 1989, he received the Ford Aerospace Corporate Technology Outstanding Principal Investigator Award for his contribution of advancing ion implantation GaAs and InGaAs MESFETs into manufacturable millimeter-wave ICs. In 1997, he received the IEEE David Sarnoff Award, and in 2000, he received the Pan Wen Yuan Outstanding Research Award in Microelectronics. In 2005, he was chosen as the first Holonyak Chair Professor of Electrical and Computer Engineering. In 2006, his transistor laser research paper was selected as one of the top five papers in the 43 year-history of Applied Physics Letters, and also was selected as one of the top 100 most important discoveries in 2005 by Discover magazine.