GeVn complexes for silicon-based room-temperature single-atom nanoelectronics

Abstract

We propose germanium-vacancy complexes (GeVn) as a viable ingredient to exploit single-atom quantum effects in silicon devices at room temperature. Our predictions, motivated by the high controllability of the location of the defect via accurate single-atom implantation techniques, are based on ab-initio Density Functional Theory calculations within a parameterfree screened-dependent hybrid functional scheme, suitable to provide reliable bandstructure energies and defect-state wavefunctions. The resulting defect-related excited states, at variance with those arising from conventional dopants such as phosphorous, turn out to be deep enough to ensure device operation up to room temperature and exhibit a far more localized wavefunction.

Position‐Controlled Functionalization of Vacancies in Silicon by Single‐Ion Implanted Germanium Atoms

“…Based on ab initio calculations, [ 3 ] some of us have recently demonstrated that Ge V complexes in silicon are stable defects, characterized by excited states deep in the bandgap, at about ≃−0.5 eV and ≃−0.35 eV from the conduction band, consistent with experiment. [ 23 ] Such impurity states have large on‐site electron–electron repulsion (≃150 meV) due to their highly localized wavefunctions (the decay length of the lowest charged state is ≃0.45 nm).…”

“…We evaluate the hopping and inter‐site repulsion parameters using the wavefunction of the electronic state occupied by an additional electron on the defect, namely the charged excitation sitting −0.5 eV below the conduction‐band bottom. [ 3 ] The use of a wavefunction obtained from ab initio calculation allows a more accurate description of deep energy levels of Ge V with respect to the usually adopted Kohn–Luttinger wavefunction which is suitable for shallow levels of conventional dopants but not appropriate for Ge V . Figure 1a shows a section of such ab initio‐computed wave function across a high‐symmetry crystal plane through two vacancy centers.…”

“…Deep-level impurities in group IV semiconductors have been envisioned as a possible route toward room-temperature quantum information processing. [1][2][3][4] Vacancies in silicon could requires operating temperature below 1.5 K, [21] preventing the exploitation of this technology between soft cryogenic and room temperatures.…”

“…Deep‐level impurities in group IV semiconductors have been envisioned as a possible route toward room‐temperature quantum information processing. [ 1–4 ] Vacancies in silicon could in principle provide deep electrically relevant individual centers suitable for high temperature quantum information manipulation, [ 5,6 ] but their positioning is rarely controllable. [ 7 ] Indeed, the miniaturization of nanoelectronic devices for quantum information processing [ 8 ] faces many technological and fundamental challenges, such as the control of effects induced by structural disorder [ 9 ] and those related to the localization of the dopant wavefunction in nanometer‐size channels.…”

Terahertz detection with an antenna-coupled highly-doped silicon quantum dot

“…The other solution is by improving the quantum efficiency by sophisticated Si doping techniques such as deterministic doping 31 to control the donor bands’ energy spread. In addition, by using a variety of donors and acceptors, it is possible to operate in a different bandwidth such as in the near-infrared range by using a deep level dopant (e.g., ~0.51 eV Ge-vacancy center as a donor 32 ). An additional advantage of using Si nanotechnology is that arrayed Si-QD detectors are compatible with mature Si integrated circuit technologies for multiple signal processing and amplification techniques, which can then be applied to THz cameras in the future.…”