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Section 2.1.1 describes the historical development through Vacuum Tube Era.

2.1. history of electron devices- vacuum tube era, solid state era and nanotechnologyera.

In 1897, while studying Cathode Ray in a Vacuum Tube, J.J.Thomson for the first time identified the Cathode Ray with ‘Electrons’. For this J.J.Thomson was awarded Nobel Prize in Physics in 1906.

Thomson’s Vacuum Tube was a very simple contraption. The Tube was evacuated to a vacuum of 10 -3 Torr by a rotary pump. 1 Torr is 1mm Hg Vacuum. 1 Atmosphere pressure will support 76cm column of Hg. We can go to still higher vacuum using diffusion pump. For MOSFET fabrication we require ion-pump which can evacuate to 10 -8 Torr.

This evacuated Vacuum Tube (VT) contains a filament, cathode and anode. Filament is made of tungsten which on passage of current gives a lot of thermal energy by resistive heating. This heats the Cathode.

Cathode is made of Strontium-BariumCuO with a work-function W F = 1eV.

The energy band diagram of Cathode is given in Figure 2.2.

As seen in Figure 2.2., Cathode is heated to 1000K.Conducting electrons in the Cathode are energetic enough to cross the Surface Barrier Potential (φs) and constitute the thermoionically emitted electrons which form a space charge cloud around the cathode as shown in Figure 2.4. As emitted electrons leave the surface of the cathode, a positive charge builds up on the cathode surface because of unbalanced charge within the cathode. This positive charge holds on to emitted electrons causing space charge cloud. From this space charge cloud electrons are pulled to the anode held at positive potential of 100V. This motion of electrons from the cathode to anode constitute the Anode Current and which was interpretated as Cathode Ray until Thomson revealed the mystery of thermoionic emission of electrons from the cathode.

Thomson studied this beam of electron meticulously and established the charge ‘q’ and q/m ratio of electron where m is the mass of electron. The set up is shown in Figure 2.3.

The verification of the negative charge of electron led J.J.Thomson to hypothesize the Plum-Pudding Model. He suggested that negatively charged electrons are swimming in a sea of positive charge. It was only later on that by Gold-foil experiment Rutherford decisively established the planetary model of atom. He found that 99% of the mass of the atom is concentrated in the nucleus and it was positively charged. Electrons are orbiting this nucleus and their opposite charges are equal in magnitude to make an atom neutral in charge.

The discovery of electrons formally launched the Branch of Engineering we know as Electronics and Communication Engineering. This was also the start of Vacuum Tube Era.

2.1.1. vacuum tube era

Vacuum Diode - After the discovery of electron in 1897, Vacuum Diode was invented by John Ambrose Fleming in 1903. Vacuum Diode is identical to the CRT shown in Figure 2.1 except that it does not have parallel set of deflecting plates and is shown in Figure2.4. I-V characteristics of the Vacuum Diode is shown in Figure 2.5.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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Source:  OpenStax, Solid state physics and devices-the harbinger of third wave of civilization. OpenStax CNX. Sep 15, 2014 Download for free at http://legacy.cnx.org/content/col11170/1.89
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