Atomic White-Out: Enabling Atomic Circuitry Through Mechanically Induced Bonding of Single Hydrogen Atoms to a Silicon Surface

We report the mechanically induced formation of a silicon-hydrogen covalent bond and its application in engineering nanoelectronic devices. We show that using the tip of a non-contact atomic force microscope (NC-AFM), a single hydrogen atom could be vertically manipulated. When applying a localized electronic excitation, a single hydrogen atom is desorbed from the hydrogen passivated surface and can be transferred to the tip apex as evidenced from a unique signature in frequency shift curves. In the absence of tunnel electrons and electric field in the scanning probe microscope junction at 0 V, the hydrogen atom at the tip apex is brought very close to a silicon dangling bond, inducing the mechanical formation of a silicon-hydrogen covalent bond and the passivation of the dangling bond. The functionalized tip was used to characterize silicon dangling bonds on the hydrogen-silicon surface, was shown to enhance the scanning tunneling microscope (STM) contrast, and allowed NC-AFM imaging with atomic and chemical bond contrasts. Through examples, we show the importance of this atomic scale mechanical manipulation technique in the engineering of the emerging technology of on-surface dangling bond based nanoelectronic devices.Comment: 9 pages (including references and Supplementary Section), 8 figures (5 in the main text, 3 in Supplementary

Binary Atomic Silicon Logic

It has long been anticipated that the ultimate in miniature circuitry will be crafted of single atoms. Despite many advances made in scanned probe microscopy studies of molecules and atoms on surfaces, challenges with patterning and limited thermal stability have remained. Here we make progress toward those challenges and demonstrate rudimentary circuit elements through the patterning of dangling bonds on a hydrogen terminated silicon surface. Dangling bonds sequester electrons both spatially and energetically in the bulk band gap, circumventing short circuiting by the substrate. We deploy paired dangling bonds occupied by one movable electron to form a binary electronic building block. Inspired by earlier quantum dot-based approaches, binary information is encoded in the electron position allowing demonstration of a binary wire and an OR gate

Single Electron Dynamics of an Atomic Silicon Quantum Dot on the H-Si(100) 2x1 Surface

Here we report the direct observation of single electron charging of a single atomic Dangling Bond (DB) on the H-Si(100) 2x1 surface. The tip of a scanning tunneling microscope is placed adjacent to the DB to serve as a single electron sensitive charge-detector. Three distinct charge states of the dangling bond, positive, neutral, and negative, are discerned. Charge state probabilities are extracted from the data, and analysis of current traces reveals the characteristic single electron charging dynamics. Filling rates are found to decay exponentially with increasing tip-DB separation, but are not a function of sample bias, while emptying rates show a very weak dependence on tip position, but a strong dependence on sample bias, consistent with the notion of an atomic quantum dot tunnel coupled to the tip on one side and the bulk silicon on the other.Comment: 7 pages, 6 figure