CPM Seminar

Atomically Precise Doping in Silicon by Scanning Tunneling Microscopy

Taylor J.Z. Stock

London Centre for Nanotechnology
University College London

In recent years, atomic-scale device fabrication has been achieved using scanning tunneling microscopy (STM) hydrogen resist lithography. This technique exploits the atomic resolution of the STM to precisely position individual dopant atoms in silicon. Specifically, a hydrogen passivation layer is patterned with the STM tip and used as a resist to spatially confine the surface chemical reaction of dopant precursor molecules on the Si(001) surface. The precisely patterned 2D dopant layers are then substitutionally incorporated into the silicon surface and encapsulated with an epitaxial silicon overlayer. Using this technique it is possible to fabricate new classes of quantum electronic devices where dopant atoms, charge carriers, and spins can be spatial confined in one, two, or three dimensions.

In this seminar, I will discuss the basic surface chemistry and materials science underpinning this fabrication scheme. Here the focus will be on our recent work to introduce arsenic as a second compatible dopant species, where previously only phosphorus was used [Ref: arXiv:1910.06685]. Additionally, I will discuss electrical, structural, and chemical characterisation of atomic-scale dopant layers and patterns using a variety of techniques including magnetotransport measurements, angle resolved photoemission, electron microscopy, and scanning microwave microscopy.