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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

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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