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Atom-Based Dimensional Metrology


To fabricate and measure solid state implementations of manufacturable atomically precise devices. Build the infrastructure to fabricate prototype few-atom structures in isotopically pure Si and characterize them using new, unique metrology capabilities. Our goal is to fabricate few-atom devices that display transistor operation or that can operate as coherent qubits, and to provide the metrology and understanding needed by US industry.

Technical Goals:

  • Enable fabrication methods capable of routine atomic precision using an STM.
  • Develop RIE etch processes that enable atomic scale alignment and pattern transfer at the atomic scale.
  • Applying these fabrication methods to enable new quantum device research that lays the foundation for future generations of memory, logic, and devices that rely on the quantum nature of the structure.
  • Develop atomic-scale calibration standards based on the crystalline lattice to support the nanotechnology and semiconductor industry.


To realize atomically precise devices we have vertically integrated a program from design and fabrication through electrical characterization, device operation and state-of-the-art atomistic modeling. The key enabling fabrication technology is hydrogen-based scanning probe lithography that allows deterministic placement of individual dopant atoms in the Si lattice. We pattern Si at the atomic scale and are implementing atomically aligned mask and etch processes, providing a method for fabricating atomically precise 3-D structures. Using recently developed NIST enriched 28Si processing we will fabricate quantum devices in an isotopically pure Si environment redefining solid-state, electron coherence times. We are implementing the fabrication infrastructure necessary to manufacture prototypical few-atom devices in a controlled solid-state environment and building the measurement framework necessary to fully characterize these devices. We are developing the fundamental theories and models needed to understand these devices at the atomic scale and the basic relationship between the atomic arrangement and final device performance.

Major Accomplishments:


  • New Phosphorus doping capability installed and made operational. Two new Si overgrowth capabilities installed - ebeam evaporation and SUSI evaporation.
  • Major upgrades to both UHV systems to enable vacuum transfers. Pumping systems upgraded to target 1x10-11 torr base pressures throughout multi-chamber facilities.
  • A UHV vacuum transfer suitcase is now operational. Both SDMD systems and the QMD system are connected via UHV transfer.


  • Won an IMS titled "Atom-based Devices: Single Atom Transistors to Solid State Quantum Computing"
  • Developed support from PML director for atom-based devices project and was awarded new base funding for project.


  • Completed Phase III DARPA project with extensive external collaborations.
  • UMD student completed PhD thesis with a research focus on modeling step flow dynamics.
An STM image to show three vertical lines patterned by a STM.
Figure 1. An STM image to show three vertical lines patterned by a STM. The distance between any two lines can be determined by counting the number of atoms separating lines.

Lead Organizational Unit:



  • JQI (Joint Quantum Institute) at University of Maryland
  • Zyvex Labs

Facilities/Tools Used:

  • System1: UHV STM with surface analysis, Phosphor doping, and Si overgrowth (ebeam).
  • System 2: UHV STM with Si overgrowth (SUSI), Auger, and oxidation. STM designed for positioning.
  • System 3: In the design phase. A new UHV STM facility with low temperature imaging and spectroscopy. This system will be targeted at atomically precise fabrication.
  • NIST Nanofab, Extensive collaborations with Quantum Measurement Division.

Figure 2. A STM image shows two Si(100) terraces and a single atomic step(height of 0.136nm) between them. A STM patterned a single line on the right side of terrace.
Figure 2. A STM image shows two Si(100) terraces and a single atomic step(height of 0.136nm) between them. A STM patterned a single line on the right side of terrace.


Richard M. Silver, Project Leader
Joseph (Joe) Fu


Kai Li
Pradeep Namboodiri
Xiqiao Wang
Xiao Deng


Physical Measurement Laboratory (PML)
Engineering Physics Division (683)

General Information:
301-975-5609 Telephone
301-869-0822 Facsimile

100 Bureau Drive, M/S 8212
Gaithersburg, Maryland 20899-8212