Enhanced Quantum Effects in an Ultra-Small Coulomb Blockaded Device Operating at Room-Temperature

An ultra-small Coulomb blockade device can be regarded as a mesoscopic artificial atom system and provides a rich experimental environment for studying quantum transport phenomena[1]. Previously, these quantum effects have been investigated using relatively large devices at ultra-low temperatures, where they give rise to a fine additional structure on the Coulomb oscillations [2-13]. Here, we report transport measurements carried out on a sub-2nm single-electron device; this size is sufficiently small that Coulomb blockade, and other quantum effects, persist up to room temperature (RT). These devices were made by scaling the size of a FinFET structure down to an ultimate limiting form, resulting in the reliable formation of a sub-2nm silicon Coulomb island. Four clear Coulomb diamonds can be observed at RT and the 2nd Coulomb diamond is unusually large, due to quantum confinement. The observed characteristics are successfully modeled on the basis of a very low electron number on the island, combined with Pauli spin exclusion. These effects offer additional functionality for future RT-operating single-electron device applicationsComment: 7 pages, 4 figure

Cutting Edge Nanotechnology

The main purpose of this book is to describe important issues in various types of devices ranging from conventional transistors (opening chapters of the book) to molecular electronic devices whose fabrication and operation is discussed in the last few chapters of the book. As such, this book can serve as a guide for identifications of important areas of research in micro, nano and molecular electronics. We deeply acknowledge valuable contributions that each of the authors made in writing these excellent chapters

Gate leakage variability in nano-CMOS transistors

Gate leakage variability in nano-scale CMOS devices is investigated through advanced modelling and simulations of planar, bulk-type MOSFETs. The motivation for the work stems from the two of the most challenging issues in front of the semiconductor industry - excessive leakage power, and device variability - both being brought about with the aggressive downscaling of device dimensions to the nanometer scale. The aim is to deliver a comprehensive tool for the assessment of gate leakage variability in realistic nano-scale CMOS transistors. We adopt a 3D drift-diffusion device simulation approach with density-gradient quantum corrections, as the most established framework for the study of device variability. The simulator is first extended to model the direct tunnelling of electrons through the gate dielectric, by means of an improved WKB approximation. A study of a 25 nm square gate n-type MOSFET demonstrates that combined effect of discrete random dopants and oxide thickness variation lead to starndard deviation of up to 50% (10%) of the mean gate leakage current in OFF(ON)-state of the transistor. There is also a 5 to 6 times increase of the magnitude of the gate current, compared to that simulated of a uniform device. A significant part of the research is dedicated to the analysis of the non-abrupt bandgap and permittivity transition at the Si/SiO2 interface. One dimensional simulation of a MOS inversion layer with a 1nm SiO2 insulator and realistic band-gap transition reveals a strong impact on subband quantisation (over 50mV reduction in the delta-valley splitting and over 20% redistribution of carriers from the delta-2 to the delta-4 valleys), and enhancement of capacitance (over 10%) and leakage (about 10 times), relative to simulations with an abrupt band-edge transition at the interface

InSb charge coupled infrared imaging device: The 20 element linear imager

The design and fabrication of the 8585 InSb charge coupled infrared imaging device (CCIRID) chip are reported. The InSb material characteristics are described along with mask and process modifications. Test results for the 2- and 20-element CCIRID's are discussed, including gate oxide characteristics, charge transfer efficiency, optical mode of operation, and development of the surface potential diagram

Nanoscale spin rectifiers controlled by the Stark effect

The control of orbital and spin state of single electrons is a key ingredient for quantum information processing, novel detection schemes, and, more generally, is of much relevance for spintronics. Coulomb and spin blockade (SB) in double quantum dots (DQDs) enable advanced single-spin operations that would be available even for room-temperature applications for sufficiently small devices. To date, however, spin operations in DQDs were observed at sub-Kelvin temperatures, a key reason being that scaling a DQD system while retaining an independent field-effect control on the individual dots is very challenging. Here we show that quantum-confined Stark effect allows an independent addressing of two dots only 5 nm apart with no need for aligned nanometer-size local gating. We thus demonstrate a scalable method to fully control a DQD device, regardless of its physical size. In the present implementation we show InAs/InP nanowire (NW) DQDs that display an experimentally detectable SB up to 10 K. We also report and discuss an unexpected re-entrant SB lifting as a function magnetic-field intensity

Decoherence in rf SQUID Qubits

We report measurements of coherence times of an rf SQUID qubit using pulsed microwaves and rapid flux pulses. The modified rf SQUID, described by an double-well potential, has independent, in situ, controls for the tilt and barrier height of the potential. The decay of coherent oscillations is dominated by the lifetime of the excited state and low frequency flux noise and is consistent with independent measurement of these quantities obtained by microwave spectroscopy, resonant tunneling between fluxoid wells and decay of the excited state. The oscillation's waveform is compared to analytical results obtained for finite decay rates and detuning and averaged over low frequency flux noise.Comment: 24 pages, 13 figures, submitted to the journal Quantum Information Processin