Nanodevices and nanostructures: quantum wires and quantum dots
ECE 423 Final Project Wan-Ching Hung Dec 12,2006
Quantum Dots and Quantum Lines
A quantum dot typically contains between 1 to 200 atoms in diameter and its length, width, and high are generally defined less than 100nm. The electron is retrained by Fermi wavelength. Quantum dot is confined in 3 dimensions and quantum line is confined in 2 dimensions.
Quantum Dots Applications
Si single electron transistors
Quantum Computer
Quantum Dots Applications
Nanobarcodes
nanobarcodes are made different quantum wires of different metals that have
different reflectivity.
Molecule capsule in drug delivery system
Quantum Confinement
Under 100nm, the wave property of electron can not be ignored.
L n 2
En
d
2
n h
2 2 2
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2m
2
dy
2
( E V ) 0
Tunneling Effect
Coulomb Blockade
a Coulomb blockade is the increased resistance at small bias voltage of an electronic device comprising at lease one low-capacitance tunnel junction.
Bottom-Up
Self Assembly
Applicatoins: solar cell, light-emitting diodes, capsule in drug delivery system
Chemical Colloidal Method
Lithography and Etching
Lithography: electron beam, ion beam, nanoimprint, dip pen nanolithography Etching: wet etching, dry etching, plasma, implantation, photo etching
Split-gate Approach
Use additional voltage to create 2 dimensional confinements to control the shape and size of the quantum dot’s gate. It’s a combination of e beam lithography, evaporation, lift off, contact annealing