Professor Stella W. Pang

University of Michigan 
Department of Electrical Engineering and Computer Science
2304 EECS Building
1301 Beal Avenue 
Ann Arbor, MI 48109-2122
Telephone: (734) 936-2962
Fax: (734) 763-9324
Email: pang@umich.edu

Associate Dean for Graduate Education
2105 LEC Building
1221 Beal Avenue 
Ann Arbor, MI 48109-2102
Telephone: (734) 647-7090
Fax: (734) 647-7045

Education

Research Interest

Nanofabrication Technology, Dry Etching, Dry Deposition, Microelectronic, Optical, and Microelectromechanical Devices

Research Projects

Research areas include nanofabrication technology, plasma etching and deposition technology, process induced damage, micromachining technology and devices, field emission devices, and quantum effect devices. High-resolution patterning and plasma processing are used to generate devices with features below 100 nm. Plasma process induced defects are identified and techniques to minimize, remove, and passivate damage have been developed. Novel techniques in micromachining are developed to create high sensitivity and high frequency resonators and sensors with merged circuits. Optical switching arrays in Si are formed using vertical Si micromirrors and high aspect ratio resonators. Uniform arrays of gated Si field emission devices are fabricated with sharp emitters and close gate-tip spacing. These high efficiency field emitters have low threshold voltage and high emission current, especially after plasma passivation or HfC coating. Controllable and low damage dry etching technology is applied to single electron transistors, in-plane gated quantum wire transistors, heterojunction bipolar transistors, optical waveguides and mirrors with high performance.

• Identify process induced defects and relate changes in electrical characteristics to optical responses. Develop novel techniques to minimize or passivate damage to provide substantial performance improvements. Model and control defect generation and distribution in Si and III-V devices.
• Develop and characterize quantum effect devices including single electron transistors, in-plane gated quantum wire transistors and quantum wires/dots for lasers and waveguides. Patterning and etching technologies are developed to fabricate high quality devices down to 20 nm.
• Develop direct nano-printing technology in metal and polymer using SiC molds for high resolution and high throughput patterning. This is the first demonstration that nanostructures down to 20 nm can be printed in metal repeatedly using a SiC mold.
• Develop novel micromachining technology to fabricate thick resonators with higher sensitivity. With this new technology, device thickness is no longer limited and the process is simplified significantly since bonding to glass is not needed and it requires only 1 mask level.
• Implementation of merged MEMS devices with on-chip circuits using thick (>10 µm) single crystal Si microstructures without bonding to glass or another wafer. Without bonding, the process is simplified significantly. The thick single crystal Si also provides higher sensitivity and higher quality factor.
• Demonstration of vertical mirrors and lenses in Si that can be controlled by integrated electrostatic drivers. Optical switching arrays with Si vertical mirrors were fabricated with large modulations of the optical signals at low power.
• Develop new technology for self-aligned field emitter arrays with sharp emitters and close gate-tip spacings. Emitters with radius of 8 nm and density >107 tips/cm2 have been demonstrated. Low turn-on voltage (16 V), high emission current (6 µA/tip), and good stability (±0.25%) were obtained which are substantially better than previously reported results.
• Develop low damage emitter etch and precise end point techniques for self-aligned HBTs. Emitter etching is stopped within 5 nm with low damage and high device performance.