Molecular Beam Epitaxy (MBE)

The molecular beam epitaxy (MBE) laboratory is the heart of the submicron center. Its purpose is to prepare high purity semiconductor epitaxial layers (such as GaAs and AlGaAs). Two MBE systems at the submicron center includes two growth chambers in addition to six other for introduction and pre-treatment of the substrates. One growth chamber is designed to produce high purity materials (growing presently 2DEG with low temperature mobility 36x106cm2/V-s) while the other growth chamber is growing semiconductor nano-wires (InAs and GaAs). A new, customized, high purity MBE system, is being delivered in Oct. 2008.

New Molecular Beam Epitaxy (MBE)

A new, customized, high purity MBE system, is being delivered in Oct. 2008.

Optical Lithography

Connecting submicron structures to the ‘outside world’ is done via optical lithography of structures greater than about one micrometer. Exposing a layer of photoresist to blue light through an optical mask, which has the desired pattern printed on it, is used to define the structures. Subsequently, the semiconductor chips are etched (or metal deposited), through the reproduced photoresist mask. Three Karl Süss systems, with the smallest possible exposed pattern ~0.6 micrometer.

Electron-beam lithography system

Submicron lithography is performed with a profession Electron Beam Writing system. The E-Beam system is used to produce structures, via a well-focused electron beam that exposes an electron sensitive film, down to a minimum size of 5 nanometer. Layer stitching accuracy is ~10 nm. A profession 9300 JEOL system.

Scanning Electron Microscope

The resolution of the scanning electron microscope is ~ 1.5nm with an in-beam detector. It is used mostly for evaluation of ultra small electronic and optical devices. It is also used to calibrate layer thickness in the molecular beam epitaxy system. A Zeiss Supra 55.

Processing

Processing systems include a load locked plasma etching system, with plasma and/or reactive on etching capabilities - used to etch vertical walls with minimum damage to lower lying layers; load locked plasma deposition system - used and to deposit insulators such as SiO2 and Si2N3. Ultra high vacuum evaporation systems (with electron beam and Joule evaporation) are used to deposit metal films for ohmic contacts and various metal gates. Rapid thermal annealing systems are used to activate ohmic contacts. A variety of characterization tools, scriber, bonders, etc.

Dilution refrigerators

Two dilution refrigerators, with base temperature of 8 mK, with magnetic field of 0-18 T, are supported by state of the art electronics driven by a computer. Cooled preamplifiers (inside the fridges) allow measuring extremely low noise electronic signals. Two new refrigerators are now on order: one, with a quick turn around time and easy to use, reaching base temperature of 15 mK, and another (DRS from Leiden Cryogenics), with a top loader probe and a Pomeranchuk cell, expecting to reach 1-4 mK.

He3 cryostat

A He3 cryostat, with a magnetic field of 0-6 T, with base temperature of 0.3 K.

Hall measurement system

An automated Hall measurements system determines the carrier density and mobility at low magnetic field (0-1 T), at temperature range 4.2-300 K.