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As is evident from Fig. (6.24) W, the base width, is limited by the resolution of the photolithographic technique which is 10um in 1960s. Also punch through has to be avoided. (Punch through occurs when C-B depletion region overlaps E-B depletion region; at this point excessive current flows and transistor action is lost ). Therefore in lateral transistors W is 5 to 10um. This large W causes a drastic deterioration of short circuit current (β fo ) and transit frequency (ω T )

From our device physics we know that Transit Time = τ transit = W 2 /(2D B ) and β fo = (τ recombination / τ transit )

Also since P doping of emitter (10 17 /cc) and collector (10 17 /cc) is heavier than N doping(10 16 /cc) of the epilayer which is base here, the depletion width extends into base region predominantly. This causes δW/δV CB to be significant which leads to significant Early Effect hence h ob and h oe (or g c and g o ) are large (the slope of I-V characteristics is large) But here BV EBO = BV CBO high is quite high.

Because of poor performance parameters of lateral transistors, the latter are fully avoided for high frequency applications. But in low frequency applications (typically below 1 MHz ) a mix of n-p-n and lateral p-n-p can give very favorable performance characteristics. Therefore such a mix is used in uA 741.

Section 6.10 Breakdown voltages of n-p-n transistor in MC1530

Referring to the doping profile of n-p-n transistor in Fig. (6.17) it is seen that

background doping of the epi-layer is N BC = 1.2 × 10 16 (cm -3 )

and N’ B = 1.8 × 10 17 (cm -3 ), emitter doping is N E =1.0 X 10 20 (cm -3 ) and W = 0.7 um.


BV CBO (determined by N BC ) = 55V.

BV EBO (determined by N B ’) = 7V.

BV CEO = BV CBO / (β o ) 1/MillerIndex = 23V

[Substrate pnp transistor :- Here p substrate is used as collector and n epilayer is used as base and p layer, for the base diffusion in npn transistor, is used as emitter. Since here W depends upon diffusion depths therefore much better performance parameter as compared to lateral pnp can be achieved. But substrate pnp can be used only in CC configuration.]

Doping profile of pnp transistor is given in Fig. (6.25)

As is evident from Fig. (6.25)

N B ’ = N BC

Therefore BV CBO = BV EBO = 55v.

Therefore if lateral pnp transistor is used in the input circuit of Op-Amp (as it is done in uA741 ) a much larger V id (differential mode signal ) can be handled by the Op-Amp.

Section 6.11 Design Considerations in the circuit layout of MC1530/31.

We have already seen the fabrication steps involved in the manufacture of MC 1530 or MC 1531. Now we will examine the design considerations involved in the circuit layout of MC -1530 on the silicon chip. MC-1530 and MC-1531 are identical circuits except for the input differential stage. MC-1530 is a direct input to a differential stage with R id = 10K whereas MC-1531 is a darlington pair input to the differential stage with R id = 1M.

We have already seen that N epi layer of the isolated island forms the collector of the transistor or the anode of the diode. ( We have shown in Sec. 6.5 that transistor is used in diode configuration by shorting collector to base). Therefore N epi layer of any isolated island will always be at some positive potential as dictated by d.c. quiescent condition of the circuit. These positive potentials set the proper operating condition of the circuit as well as they help isolate the components from the substrate and from one another.

Questions & Answers

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
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
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.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket 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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