23-05-2014, 12:55 PM
Single-Electron Devices
[attachment=63590]
Introduction
Single electronics is one of the emerging technology that deal with control and transport of a single electron. The fundamental physical principal of single –electronics is tunnelling effect and phenomena of coulomb blockade.
Evolution Of Single-Electron Devices
Since the invention of the transistor by John Bardeen and William Shockley in 1948 constant miniaturization has lead to devices with dimensions well below the 100 nm limit. Originally designed to simply emulate the vacuum tube, the transistor soon proved to provide a lot more potential for speed, power consumption and reliability. In its most widespread configuration as metal oxide-semiconductor field-effect transistor (MOSFET).
The relentless quest for device miniaturization is something that has been with semiconductor technology since its early evolution starting in the 1950s. This search is driven by a few facts which became obvious at the latest when the first steps towards integrated circuits where made in the late 1950s. First, the reduced volume of a miniaturized transistor allows for lower power dissipation. Second, the consequently lower capacitances and shorter interconnects lead to faster systems. Finally, relative costs drop with more devices on ever-increasing chip sizes.
Modern Semiconductor Device Simulation
From the very beginning of semiconductor technology it was thought that numerical, physics-based analysis of devices could help a great deal in their understanding. Nowadays, simulation and modeling of semiconductor devices both at the process and the device level has become one of the most important development methodologies in industry and eventually has developed into an ever-growing industry itself.
Transport Models
When the channel length is larger than 0.1μm, we can apply the macroscopic transport models that involve macroscopic variables such as the average electron density, velocity, energy, and electron temperature. This can be divided into two classes: Kinetic models and Quasi-hydrodynamic models. For each of these classes we can consider classical (semi) and quantum models.
If the channel length is smaller than 0.1μm, the assumptions of the macroscopic transport models are generally not valid any more.
Motivation
There are three primary challenges to the continued scaling of transistors. The first set of challenges involves the physical assumptions underlying the operation of these devices, and the way that some of these assumptions break down as physical dimensions shrink. Oxides, for example, are used in several parts of integrated circuits to provide insulation between conducting regions. As oxide thicknesses approach the order of a few nanometers, however, electrons can increasingly tunnel through these barriers, leading to unacceptable levels of leakage current. Another problem arises when device volumes become small enough that statistical variations in the dopant distribution result in substantial diferences in characteristics from one device to the next .
[attachment=63590]
Introduction
Single electronics is one of the emerging technology that deal with control and transport of a single electron. The fundamental physical principal of single –electronics is tunnelling effect and phenomena of coulomb blockade.
Evolution Of Single-Electron Devices
Since the invention of the transistor by John Bardeen and William Shockley in 1948 constant miniaturization has lead to devices with dimensions well below the 100 nm limit. Originally designed to simply emulate the vacuum tube, the transistor soon proved to provide a lot more potential for speed, power consumption and reliability. In its most widespread configuration as metal oxide-semiconductor field-effect transistor (MOSFET).
The relentless quest for device miniaturization is something that has been with semiconductor technology since its early evolution starting in the 1950s. This search is driven by a few facts which became obvious at the latest when the first steps towards integrated circuits where made in the late 1950s. First, the reduced volume of a miniaturized transistor allows for lower power dissipation. Second, the consequently lower capacitances and shorter interconnects lead to faster systems. Finally, relative costs drop with more devices on ever-increasing chip sizes.
Modern Semiconductor Device Simulation
From the very beginning of semiconductor technology it was thought that numerical, physics-based analysis of devices could help a great deal in their understanding. Nowadays, simulation and modeling of semiconductor devices both at the process and the device level has become one of the most important development methodologies in industry and eventually has developed into an ever-growing industry itself.
Transport Models
When the channel length is larger than 0.1μm, we can apply the macroscopic transport models that involve macroscopic variables such as the average electron density, velocity, energy, and electron temperature. This can be divided into two classes: Kinetic models and Quasi-hydrodynamic models. For each of these classes we can consider classical (semi) and quantum models.
If the channel length is smaller than 0.1μm, the assumptions of the macroscopic transport models are generally not valid any more.
Motivation
There are three primary challenges to the continued scaling of transistors. The first set of challenges involves the physical assumptions underlying the operation of these devices, and the way that some of these assumptions break down as physical dimensions shrink. Oxides, for example, are used in several parts of integrated circuits to provide insulation between conducting regions. As oxide thicknesses approach the order of a few nanometers, however, electrons can increasingly tunnel through these barriers, leading to unacceptable levels of leakage current. Another problem arises when device volumes become small enough that statistical variations in the dopant distribution result in substantial diferences in characteristics from one device to the next .