EBL: Electron-Beam Lithography Laboratory

The EBL is located in room 1322, A.V. Williams Building. The electron-beam lithography system consists of a JEOL 6400 scanning electron microscope and a computer-controlled electron-beam steering system. Conventional photolithography can transfer a pattern on the photomask to the photoresist on top of wafers with a resolution approximately the same as the wavelength of photons used. In contract, for electron beam lithography, a tightly-focused electron beam is steered to directly expose an electron-sensitive polymer. For a “positive tone” electron-beam resist, the exposed polymer should be broken into smaller chains, thus easier to dissolve in a solvent in the development process. Our typical feature size on the electron beam resist is about 70 nm, and a higher resolution can be obtained by using various laboratory tricks. We next transferred this pattern on the electron beam resist to the semiconductor heterojunctions below, and carried out magnetoresistance measurements.

Recent projects:

• Single electron confinement in an InAs quantum dot and probed by single electron transistors
• Single electron confinement in silicon, and verified also by single electron transistors
• Spin Berry phase, electron waveguide in InAs quantum wires
• Single electron tunneling in double barrier resonant tunneling structures

Supported by:

• Laboratory for Physical Sciences/ National Security Agency
• Office of Naval Research
• Naval Research Laboratory

Pictures:

1. Aharonov-Bohm quantum interference ring

2. InAs single electron quantum transistor

Contact:

Prof. C.H. Yang, ECE, UMCP (yang@ece.umd.edu)