Joseph A. Hagmann, Xiqiao Wang, Pradeep N. Namboodiri, Richard M. Silver, Curt A. Richter
An improved capacity to control matter at the atomic scale is central to the advancement of nanotechnology. The complementary metal-oxide-semiconductor (CMOS) devices that power existing computing technology, which continue to scale down in size as predicted by Gordon Moore in 1965, now approach a scale at which the number and exact position of individual dopant atoms within the device determine the electronic qualities of the device,1 affecting device performance variability when dopants are randomly distributed in the silicon lattice, and revealing a physical limit on the degree to which CMOS technology can be scaled.2 The development of devices based on the deterministic placement of dopants in silicon is an exciting avenue towards the pursuit of quantum computing architectures due to long spin-coherence3 and spin-relaxation4 times in dopants and because such devices would easily be made compatible with existing silicon CMOS technology.5 The key building block for such devices is the deterministic formation of dopant monolayers (in this case phosphorous) and their overgrowth with high quality crystalline Si. Lithographically defined dopant delta-layers can be formed with a scanning tunnel microscope which can pattern device features on a hydrogen-terminated silicon surface by exposing Si dangling bonds at specific locations and implanting phosphorus at these locations with atomic precision (e.g., Fig. 1). We describe advancements in the dopant formation and overgrowth processes necessary to produce prototypical few-atom devices in a controlled solid-state environment. The structure of the samples is determined from a suite of measurements that includes scanning tunneling microscopy (STM), transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), and directly correlated with the electrical properties as determined by variable-temperature magnetotransport.
International Semiconductor Device Research Symposium 2016
, Wang, X.
, Namboodiri, P.
, Silver, R.
and Richter, C.
Atomically precise device fabrication, International Semiconductor Device Research Symposium 2016, Bethesda, MD
(Accessed June 10, 2023)