Single Electron Transistor

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SINGLE ELECTRON TRANSISTOR

SEMINAR

ABSTRACT

A single-electron transistor consists of a small conducting island connected to the source and drain leads by tunnel junctions and connected to one or more gates. The nanometre scale conductive island is embedded in an insulating material. Gate signals are capacitive coupled to the island. Two gate signals can be applied to the island out of which one is optional. Here, only one electron can tunnel from source to drain. The processes that take place in this island (nano structure) are coulomb blockade phenomenon and single electron tunnelling.

CONTENTS

CHAPTER 1: List of figures……………………………………………..6 CHAPTER 2: List of tables………………………………………………7 CHAPTER 3: Introduction……………………………………………….8 CHAPTER 4: Single-Electron Transistors…………………….…….…...9 CHAPTER 5: Equivalent Circuit for SET...……………………………..13 CHAPTER 6: SET Characteristics..………………………………...…….17 CHAPTER 7: Comparison between SET and MOSFET............................19 CHAPTER 8: Conclusions………… …..…………………………….....20 CHAPTER 9: References ……………………………………………….21

CHAPTER 1

LIST OF FIGURES

SL. noFig noDescription Page. No
1Fig 1EVOLUTION OF SET FROM SIMPLE TUNNEL
JUNCTION9
2Fig 2CHARGE FLOW IN CONDUCTORS AND TUNNEL
JUCTION10
3Fig 3CURRENT BIASED TUNNEL JUNCTION SHOWING
COULOMB OSCILLATIONS11
4Fig 4EQUIVALENT CIRCUIT FOR SINGLE ELECTRON
TRANSISTOR13
5Fig 5SCHEMATIC AND DEVICE PARAMETERS OF A SET
13
6Fig 6SET ID VS VDS CHARACTERISTICS
16
7Fig 7IDS VS VGS CHARACTERISTICS OF SET17
8Fig 8GATE ENERGY BAND DIAGRAM17

CHAPTER 2

LIST OF TABLES

SL. NoTable. noDescriptionPage. No
1Table 1COMPARISON BETWEEN SETS AND MOSFETS
19

CHAPTER 3

INTRODUCTION:

SETs are now becoming attractive candidates of post-CMOS VLSI mainly due to its (i)nano feature size
(ii)ultra low power density

About SET

A single-electron transistor consists of a small conducting island connected to the source and drain leads by tunnel junctions and connected to one or more gates. The nanometre scale conductive island is embedded in an insulating material. Gate signals are capacitive coupled to the island. Two gate signals can be applied to the island out of which one is optional. Here, only one electron can tunnel from source to drain. The processes that take place in this island (nano structure) are coulomb blockade phenomenon and single electron tunnelling.

CHAPTER 4

SINGLE-ELECTRON TRANSISTORS
This section introduces and enlightens the reader about the basic architecture and characteristics of the single-electron transistor (SET) and its differences from the MOSFET. The detailed physics of the carrier transport in the SET will be discussed in The basic element of a SET is the tunnel junction, and hence, unlike MOSFETs, the quantum mechanical tunneling of the electrons through the tunnel barrier controls current conduction in a SET. If we consider a piece of conductor and divide it into two parts by inserting an ultrathin dielectric, the overall structure will behave as a tunnel junction, as shown in Figure 1(a). It should be noted that because it is so thin, the insulator actually acts as a leaky capacitor as electrons tunnel through it. Now the most basic architecture of a single-electron device (SED) can be constructed by placing two such tunnel junctions in series, as shown in Figure 1(b). The piece of the conductor, which is sandwiched between two tunnel junctions, is known as the island (or grain, or dot). This device is called a SED because only one electron can travel from one terminal to another at a time (under some particular assumptions). Therefore, in SEDs,...
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