Based at UNSW Sydney, the Atom Fabrication Laboratories were established in 2001 and provide a unique set of facilities world-wide for the development of atomically precise devices in silicon. These laboratories house 6 state of the art scanning tunneling microscopes, including a combined Multi-scan STM-SEM/MBE system, an Omicron Nanoprobe (4-point probe STM), a low temperature STM and several variable Temperature STMs from Omicron Nanotechnology GmbH. Each of these systems offers the combination of high quality silicon growth and high resolution STM.
The majority of work on understanding surface chemistry is performed on a Variable Temperature Scanning Tunneling Microscope (VT-STM) from Omicron Nanotechnology and consists of a custom-configured, triple-chamber UHV STM/MBE system. The STMs can be operated at temperatures ranging from 25 K to 1100 K and a second UHV chamber houses silicon sources for the MBE growth epitaxial silicon with thicknesses up to hundreds of nanometers.
The multi-chamber STM-SEM/MBE system was our first system to undertake qubit fabrication development and provides the necessary registration and high purity silicon growth capabilities required for multi-qubit fabrication. Specifically, the MBE system is capable of device quality Si and SiGe growth wafers up to 4” diameter, with low background doping levels. A low temperature oxide chamber is available for the development of high quality silicon dioxide barrier layers, using resistive silicon sublimation (SUSI) and an RF plasma neutral atomic oxygen source. Operating under UHV conditions, the STM-SEM and MBE chambers are physically connected even though they are housed in different, acoustically shielded laboratories within the AFF. The STM system incorporates an SEM that allows registration markers to be easily found without damaging the STM tip. A specially designed optical position readout system is also incorporated to allow precise alignment of features during successive fabrication steps.
The Omicron Nanoprobe four probe STM system is configured for in-situ electrical characterization of nano- and atomic-scale devices and a separate combined Variable Temperature (VT) STM and a Low Temperature (LT) STM system is used to directly imagine the donor wavefunctions, which when coupled with a Nanonis STM controller from SPECS Zurich allows state-of-the-art spectroscopy.
In 2016 a new R&D facility was completed adjacent to the existing Centre laboratories for the Centre’s spin-out company, Silicon Quantum Computing Pty Ltd. This 3-floor building doubles the experimental facilities available for the development of a prototype processor, including a considerable numbers of new STMs, fridges and a dedicated fast processing clean room facility. This building is operated with UPS and generator supported power supply, a Helium gas recovery network, and a large cooling water capacity for its He compressor.