Atomically manufactured nickel–silicon quantum dots displaying robust resonant tunneling and negative differential resistance

Abstract

Self-assembly: nickel-silicon clusters behave as quantum dots Silicon-based quantum dots are artificial two-level systems, whose long coherence times make them ideal candidates as qubits for quantum information technology. Researchers from the University of Illinois at Chicago and Argonne National Laboratory present an approach to fabricate via self-assembly randomly distributed clusters, by manipulating the density of nickel on a silicon substrate. Deposition of nickel below a critical density leads to the formation of two types of clusters, both of which behave as isolated quantum dots: confinement gives rise to well-spaced quantized levels similar to the structure of atoms, while measurements under positive and negative bias reveal two symmetric resonances, signatures of tunneling through the highest occupied and lowest unoccupied energy levels, respectively. Such a scalable fabrication method, based on self-assembly, may be further exploited for the design of silicon-based qubits