Transport in split gate MOS quantum dot structures (original) (raw)

Transport in split-gate silicon quantum dots

Superlattices and Microstructures, 2000

We report on the transport properties of novel Si quantum dot structures with controllable electron number through both top and side gates. Quantum dots were fabricated by a split-gate technique within a standard MOSFET process. Four-terminal dc electrical measurements were performed at 4.2 K in a liquid helium cryostat. Strong oscillations in the conductance through the dot are observed as a function of both the top gate bias and of the plunger bias. An overall monotonic and quasi-periodic movement of the peak conductance is observed which is believed to be associated with the bare level structure of the electronic states in the dot coupled with the Coulomb charging energy. Crossing behavior is observed as well, suggestive of either many-body effects or symmetry breaking of the dot states by the applied bias.

Electrostically defined few-electron double quantum dot in silicon

2009

A few-electron double quantum dot was fabricated using metal-oxide-semiconductor(MOS)-compatible technology and low-temperature transport measurements were performed to study the energy spectrum of the device. The double dot structure is electrically tunable, enabling the inter-dot coupling to be adjusted over a wide range, as observed in the charge stability diagram. Resonant single-electron tunneling through ground and excited states of the double dot was clearly observed in bias spectroscopy measurements.

Electrostatically defined few-electron double quantum dot in silicon

Applied Physics Letters, 2009

A few-electron double quantum dot was fabricated using metal-oxide-semiconductor(MOS)-compatible technology and low-temperature transport measurements were performed to study the energy spectrum of the device. The double dot structure is electrically tunable, enabling the inter-dot coupling to be adjusted over a wide range, as observed in the charge stability diagram. Resonant single-electron tunneling through ground and excited states of the double dot was clearly observed in bias spectroscopy measurements.

Atomic-Scale, All Epitaxial In-Plane Gated Donor Quantum Dot in Silicon

Nano Letters, 2009

Nanoscale control of doping profiles in semiconductor devices is becoming of critical importance as channel length and pitch in metal oxide semiconductor field effect transistors (MOSFETs) continue to shrink toward a few nanometers. 1,2 Scanning tunneling microscope (STM) directed self-assembly of dopants is currently the only proven method for fabricating atomically precise electronic devices in silicon. To date this technology has realized individual components of a complete device with a major obstacle being the ability to electrically gate devices. Here we demonstrate a fully functional multiterminal quantum dot device with integrated donor based in-plane gates epitaxially assembled on a single atomic plane of a silicon (001) surface. We show that such in-plane regions of highly doped silicon can be used to gate nanostructures resulting in highly stable Coulomb blockade (CB) oscillations in a donor-based quantum dot. In particular, we compare the use of these all epitaxial in-plane gates with conventional surface gates and find superior stability of the former. These results show that in the absence of the randomizing influences of interface and surface defects the electronic stability of dots in silicon can be comparable or better than that of quantum dots defined in other material systems. We anticipate our experiments will open the door for controlled scaling of silicon devices toward the single donor limit.

A Multi-Purpose Electrostatically Defined Silicon Quantum Dot Structure

Japanese Journal of Applied Physics, 2012

Small size and good coupling control between dots are the key parameters for useful coupled quantum dot devices. Using a new approach of electrostatically defined silicon double quantum dot device recently proposed, we design and simulate a silicon quantum dot structure that exhibits multi functionality. Control on potential tunnel barrier using side gates, as well as the preparation of series-coupled and parallel-coupled double quantum dot structure are demonstrated and explained by numerical simulation on electron distribution profile.

Transition from MOSFET to Quantum Dot: An Overview

The quantization of electron energies in nano crystals leads to dramatic changes in electron transport and optical properties. For quantum effect to work properly in any system the spacing of energy level must be larger in comparison to K B T and for room temperature operation; this implies that the diameter of the potential box must be at most a few nano-meters. In this work, we have given theoretical idea of a quantum dot starting from the electron transport in MOSFET. Then, we have shown that for quantum effect to work properly the size of the quantum dot should be in nano-scale using quantum mechanics.

Finite-element analysis of a silicon-based double quantum dot structure

Physical Review B, 2006

We present finite-element solutions of the Laplace equation for the silicon-based trench-isolated double quantum-dot and the capacitively-coupled single-electron transistor device architecture. This system is a candidate for charge and spin-based quantum computation in the solid state, as demonstrated by recent coherent-charge oscillation experiments. Our key findings demonstrate control of the electric potential and electric field in the vicinity of the double quantum-dot by the electric potential applied to the in-plane gates. This constitutes a useful theoretical analysis of the silicon-based architecture for quantum information processing applications.

Electron transport through silicon serial triple quantum dots

Solid-State Electronics, 2009

We study the electron transport through silicon serial triple quantum dots (TQDs) formed effectively in a lithographically-defined multiple quantum dot system on a silicon-on-insulator substrate at a temperature of 4.2 K. Our serial TQDs are composed of two lithographically-patterned QDs and another one inbetween formed by stress during the pattern-dependent oxidation process. The TQDs formation is confirmed by equivalent circuit simulations, which show an excellent agreement with the experimental results. With detailed analysis of the charge configurations in the TQDs, we discuss the distinct properties of the TQDs, including electron transport at the charge quadruple points. In addition, we discuss higher order tunneling processes of the TQDs. The analysis of electron states in the silicon TQDs is a crucial step toward the future implementation of integrated silicon quantum information devices.