K. Eng

Enhancement-mode double-top-gated metal-oxide-semiconductor nanostructures with tunable lateral geometry

We present measurements of silicon (Si) metal-oxide-semiconductor (MOS) nanostructures that are fabricated using a process that facilitates essentially arbitrary gate geometries. Stable Coulomb-blockade behavior showing single-period conductance oscillations that are consistent with a lithographically defined quantum dot is exhibited in several MOS quantum dots with an open-lateral quantum-dot geometry. Decreases in mobility and increases in charge defect densities (i.e., interface traps and fixed-oxide charge) are measured for critical process steps, and we correlate low disorder behavior with a quantitative defect density. This work provides quantitative guidance that has not been previously established about defect densities and their role in gated Si quantum dots. These devices make use of a double-layer gate stack in which many regions, including the critical gate oxide, were fabricated in a fully qualified complementary metal-oxide semiconductor facility.

Charge sensing in enhancement mode double-top-gated metal-oxide-semiconductor quantum dots

Laterally coupled charge sensing of quantum dots is highly desirable because it enables measurement even when conduction through the quantum dot itself is suppressed. In this work, we demonstrate such charge sensing in a double-top-gated metal-oxide-semiconductor system. The current through a point contact constriction integrated near a quantum dot shows sharp 2% changes corresponding to charge transitions between the dot and a nearby lead. We extract the coupling capacitance between the charge sensor and the quantum dot, and we show that it agrees well with a three-dimensional capacitance model of the integrated sensor and quantum dot system.

Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry

We present transport measurements of a tunable silicon metal-oxide semiconductor double quantum dot device with lateral geometry. The experimentally extracted gate-to-dot capacitances show that the device is largely symmetric under the gate voltages applied. Intriguingly, these gate voltages themselves are not symmetric. A comparison with numerical simulations indicates that the applied gate voltages serve to offset an intrinsic asymmetry in the physical device. We also show a transition from a large single dot to two well isolated coupled dots, where the central gate of the device is used to controllably tune the interdot coupling.

Temperature-dependent transport in a sixfold degenerate two-dimensional electron system on a H-Si(111) surface

Low-field magnetotransport measurements on a high-mobility

Steps Towards Fabricating Cryogenic CMOS Compatible Single Electron Devices

(\ensuremath{\mu}=110,000\text{ }{\text{cm}}^{2}/\text{Vs})

Observation of percolation-induced two-dimensional metal-insulator transition in a Si MOSFET

two-dimensional electron system on a H-terminated Si(111) surface reveal a sixfold valley degeneracy with a valley splitting

Triangulating the source of tunneling resonances in a point contact with nanometer scale sensitivity

\ensuremath{\le}0.1\text{ }\text{K}

Enhancement of valley splitting in (100) Si MOSFETs at high magnetic fields

. The zero-field resistivity

Coulomb Blockade in Double Top Gated Si MOS Nano-Structures with Integrated Charge Sensing

{\ensuremath{\rho}}_{xx}

Temperature-dependent transport in a sixfold degenerate 2D electron system on a H-Si(111) surface

displays strong temperature dependence for