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Section 3.3. Covers the Physics, Symbol and I-V characteristics of Zener Diode, Tunnel Diode and Backward Diode.

3.3.quantum mechanical diodes.

Till now we have studied classical diodes. Classical diodes are fabricated using non-degenerate semiconductor. Doping of 10 17 /cc or less is non-degenerate semi-conductor. Doping in the range of 10 18 /cc or more gives rise to degenerate semi-conductor.

In non-degenerate semi-conductors we have drift and diffusion of carriers. In degenerate semi-conductor apart from drift and diffusion we have band-to-band tunneling which is a purely quantum-mechanical transport mechanism.

I have talked about Quantum Mechanical tunneling in Chapter 1, Part 8. We will briefly review it in this Section.

An electron in an infinite potential well can never come out of the potential well. Electron in finite potential well with thick potential wall can come out of the potential well if by photon excitation or by thermal excitation it gains sufficient energy to cross the surface potential barrier and escape into vacuum above 0 eV energy level. These processes are known as Photoionic-emission or Thermoionic-emission. But there is a third case where the electron is trapped in a potential well with thin potential walls. The potential walls are as thin as 10A° to 100A° as shown in the Figure ( ) in Chapter 1 Part8 .In this case there is a finite probability of finding the electron outside the potential well by the process of tunneling.

The Tunneling factor is calculated to be:

Substituting the values of the different parameters, the values of Tunneling Factor is tabulated in Table 3.3.1.

Table 3.3.1.Qunatum Mechanical Tunneling Ratio for different Wall thickness and different Barrier Potential.

W (qV 1 -E) Exponent term T Comments
10A° 1eV -10.2463 3.5×10 -5 With 10A° wall thickness and 1eV well depth there is a very low probability of finding 3.5 electron in 100,000 electrons.
5A° 1eV -5.12317 6×10 -3 With wall thickness reduced to 5A° but well depth kept constant tunneling increases to 6 out of 1000electrons.
1A° 1eV -1.02463 0.36 With wall thickness reduced to 1A° but depth well kept constant tunneling increases to 36% .
1A° 10eV -3.24018 0.04 With wall thickness kept at 1A° but depth well increased to 10eV tunneling again decreases to 4% .
1A° 100eV -10.2463 3.5×10 -5 With wall thickness kept at 1A° but depth well increased to 100eV tunneling drastically decreases to . 3.5 electron in 100,000 electrons.

As the doping density is increased we encounter 4 different classes of devices:

  1. Classical Diode with an Avalanche Breakdown Voltage of BV A from 30V to 100V.
  2. Zener Diode with a zener breakdown of V Z = 4V and below.
  3. Backward Diode which conducts in forward as well as backwarddirections.
  4. Tunnel Diode which has N-Type Negative Resistance Region(NIR).

The I-V characteristics of these four diodes are shown in Figure 3.19.

We are considering an abrupt Si-diode with symmetrical N-type and P-type doping. Therefore the the built-in potential is given by the following formula:

Depletion Width (d) is given by the following fomula:

Questions & Answers

does psychology deal with love?
Mohammed Reply
Maybe, i think
I definitely would say yes
how so
there are so many different reasons why you can fall in love with someone, many of them develope subconsciously -> psychology
love messes with the brain, a lot, ergo I believe that Psychology does indeed deal with love
what is synapse
Katie Reply
In the central nervous system, a synapse is a small gap at the end of a neuron that allows a signal to pass from one neuron to the next. synapse are found where nerve cells connect with other nerve cells
can you do auto book auto
Mariah Reply
WHT u mean?
heyy, may i join the conversation please?
edem Reply
who is the father of psychology
Richy Reply
and please, how would you guys, describe the study of psychology at college ?
psychologist student?
i mean not yet but am about to start college so wanna know how is it(college in general and psychology course) please
Psychology is the study of mind and behaviour. So if you will take psychology as a subject so you will get to know how your everything (physical, mental, social, spiritual aspects) effects your behaviour
With this brief knowledge you can help people to cope up with their problems and only you can guide them correctly
And if you go for further specialisations you can study hypnosis, face reading, body language etc
Thanks a lot🙏🏾 And ik some of the stuffs u said but i am also going to write thesis, right ?
ok no prob, thanks a lot🙏🏾✨
hae everyone, hope you are well this evning my question is what is the difference between drive and motivation
good question
drive is more like an impulse or urge and i think they both go together (drive and motivation) even if there is a slight difference
@ Michael Drive is delivered to be innate without the use of an external stimuli, motivation normally evolves an outside stimuli which may include praise, appreciate, or reward.
*believed...sorry for typo
@Reginald, can't the motivation come from the inner self?
Good question, please give an example.
can we say desire of success for example
Wilhelm Wundt is the father of psychology
Wilhem Wundt thank you for the road that you opened.
You mean who is the father of having a great educated argumentative guess? nothing is more wrong than this question. The question is you should ask yourselfs is, how sure are you abour their scientific studying? one's percieved assimilated approach to judging another person and saying they are
the biggest problem with scientific research and data is that ya you could get the same result 1000 times then it could go the other way 1000 times, but we would never know that and we did, we would still say ya but the proof is there. The only thing science proves is that humanity has
no facts about human behavior in the scientific context, but more in the trial and error.. sorry to tell you, but so far no one has proven Father of anything, thats up to you and i, judgement is bias, science is good enough lazy
cognitive development is the growing and development of the brain.
Jessy Reply
Anyone knows about Techno-fascism?
Hussein Reply
Ecofascism is a theoretical political model in which an authoritarian government would require individuals to sacrifice their own interests to the "organic whole of nature". The term is also used as a rhetorical pejorative to undermine the environmental movement.
what's the big difference between prejudice and discrimination?
Danice Reply
A prejudiced person may not act on their attitude.  Therefore, someone can be prejudiced towards a certain group but not discriminate against them.  Also, prejudice includes all three components of an attitude (affective, behavioral and cognitive), whereas discrimination just involves behavior
Nancy Lee
what is all about cognitive development?
cognitive development is the growing and development of the brain
how do you control a variable when using spss whilst running a pearsons correlation analysis?
Jessie Reply
it dependa on your study. according to what you want to say and explain your result
why does it say her and she
Jayla Reply
stages of cognitive development
brivia Reply
sensory preoperatinal concrete formal
what is psychology
Chethani Reply
the study of insecurities and the effect on the host .
Psychology is the scientific study of behavior & mental processes
psychology is science about learning human behaviour
In thinking about the case of Candace described earlier, do you think that Candace benefitted or suffered as a result of consistently being passed on to the next grade?
Nene Reply
what is reward
Angeles Reply
reward is a technique to change behaviour
Reward is a way to promote a specific behaviour or to teach someone/ something to behave a specific way or perform a specific task.
a reward is something that is usually associated with desirable behavior. The child got a reward for winning the game. A reinforcer is different in that a reinforcer is anything that increases behavior, even if it is increasing an undesirable behavior.
reward is earned effort realized
why heroine addicted people smoke heroine in a dirty and polluted place ?
Najeem Reply
/i don't know
I believe they don't wanna be seen
Rajendra Singh I'm asking from those who know thanks for your comment
Ruphine it's not a scientific answer
more my personal opinions and experiences than a real answer but more of an answer than the question marks
what's the data or fact that actually say that heroine smokers host in dirty and polluted place.
Generally the more time an addict is using and the harder they use the more their life and everything around them crumbles. it's quite common to find neat respectable clean users but over time the addiction increases and their health declines along with their ability to keep up day to day duties.
I'll see if I can find some links for you to have a read.
hi. as heroine affedted exactly on the brain, it should be because the chages heroine makes on frintal lobe and sensory and motor parts. after a while the cannot behave in a normal way. in a way heroine ruines the neurones
The things said in the thread are some of the most horridly presumptuous & unwarrantedly pretentious statements I've read in my entire life. It's distastefully disrespect, to say the least.
Pouran Hi! thanks for answering I'm agree with your opinion and may the answer be the same
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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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