Most generally a class of materials that are neither insulators or conductors in their natural state but which can be manipulated via doping or electric fields to change the conduction state. Silicon, Germanium, GaAs are some usual materials. The term is also used to speak about devices that are ...

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What's the current-vs-bias difference between a conductor and a semiconductor with free charge carriers in its conduction band?

What are the electrical differences between a piece of metal and a piece of a (heavily) doped n-Si? How would the difference in charge carrier concentration affect current flow under low-to-breakdown ...
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29 views

Diffusion process in p-n junction

While studying about Semiconductors I couldn't get why "Negative charge stop electrons from further diffusion and Positive charge stop holes from further diffusion" as stated in (p.6) of the ...
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2answers
78 views

Dark current of photodiode gets higher after heating, why?

I'm doing some experiments using photodiodes. I raised the temperature to about 1000 degree Celsius for 1 second with melting AuSn near the PIN junction. Then the dark current of photodiode is higher ...
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1answer
40 views

Finding depletion region without built in potential

I am trying to solve a problem as to find the depletion region's width of a p+-n-n diode. I am given the width of the first n region and the doping of both n regions. Here is the problem: I ...
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40 views

Cannot find built in potential for this problem

I am doing some homework for my semiconductor physics class but cannot for the life of me find out how to continue... Here is the problem: A p+ n junction is formed in an n-type substrate with ND = ...
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5answers
116 views

Why do we need transforms (Fourier, Laplace, Z and wavelet etc.) for a signal to analyse?

Why do we need transforms (Fourier, Laplace, Z and wavelet etc.) for a signal to analyse? Is it necessary for practical calculations and analysis?
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49 views

Charge carrier concentration - intrinsic and extrinsic semiconductors

We define the charge carrier concentration in intrinsic semiconductors as: $$n^2_i = n_h \times n_e$$ In intrinsic semiconductors we say that these will be equal in number, and hence $$n_i = n_h = ...
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2answers
289 views

Making transistors or semiconductors at home

The transistor was invented some 50 65 years ago, so is it not about time to be able to make transistors or other semiconductors at home? Would that be possible?
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1answer
74 views

Metal semiconductor contacts

I’m headed back to the CNF (http://www.cnf.cornell.edu/) shortly. It’s a user clean room facility for semiconductor processing. My goal is to make some very simple samples, for use in student teaching ...
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1answer
70 views

Why does it take several seconds of time for the photodiodes to come out of saturation?

I am currently studying about photodiodes and came across this fact that photodiodes take quite a bit of time to come out of the saturation. What really happens during this time (after it is saturated ...
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3answers
116 views

How to remove energy from inductor using semiconductors?

So I have this coil and I'm driving dc current through it. This coil has inductance and thus stores energy from the dc current. I have to remove this energy before I can change the polarity of my ...
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1answer
139 views

How to build an H-bridge using MOSFETs? [duplicate]

I want to reverse the polarity of my current source, which is a capacitor in this case, in the middle of discharging phase. Also the capacitor bank is being discharged through a coil to make a short ...
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1answer
44 views

What happens on heating an intrinsic semiconductor?

Suppose I have an intrinsic semiconductor and I heat it up on one side. What will be the changes that will occur? As far as I know it won't become an extrinsic semiconductor because that would need to ...
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3answers
216 views

Transistors why does increasing base current increase collector current?

I am new to this area so please can you keep your answers simple, thanks. From what I know for an npn transistor in the common-emitter connection the base-emitter junction is in the forward bias and ...
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2answers
86 views

Can (CPU) logic and (flash) memory be located on the same die?

Is it possible to manufacture semiconductors in a way that places logic (for example, a CPU core) on the same die with non-volatile flash (or other EEPROM memory) circuits? What about DRAM? It ...
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1answer
113 views

If the depletion layer of a transistor collector/base junction is thick, why are majority carriers still collected?

In "Principles of transistor circuits, 8th edition" (top of p26) it is said that once holes have been injected in the base region by a forward biased base-emitter junction (which I understand) of a ...
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0answers
24 views

Find the Output curve for the given Input Curve

For the circuit given below find the output wave form for the given input wave. The following are the answer choices for the curve of Vout. The answer choice selected in my book is (3) Please ...
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1answer
34 views

Why is the voltage across a PN junction 0 v when it is in open circuit conditions? [duplicate]

Why is the voltage across a PN junction 0 v when it is in open circuit conditions ?
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1answer
65 views

Cutoff and Conducting diodes

Why is D1 considered cutoff and D2 considered conducting ? Note : I am working with constant voltage model where the diode voltage is 0.7v and I need to figure out I and V. Please explain why D1 is ...
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3answers
125 views

Instructions on how to build electronic devices [duplicate]

I have got plenty of books in the theory of electronic devices, but I wish to build these transistors (BJT, MOSFETS, etc) and diodes by myself. Which books are there in offer to learn how to do this? ...
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1answer
116 views

Why can current flow through the reverse biased base-collector junction (N-P junction) in a BJT with a forward biased base-emitter junction?

If the base-emitter junction of a BJT is forward biased, then current can flow through the reverse biased base-collector junction (N-P junction). This disagrees with my understanding of the PN ...
2
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3answers
75 views

reason for degradation of photovoltaics

Photovoltaic panels can have 20 or 25 year underwritten warranties with a guaranteed remaining efficiency of 80 % of the new panel. That means, that photovoltaic panels seem to degrade somehow. Why ...
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1answer
78 views

Dependence of mobility of charge carriers in semiconductor on the applied electricfield

The mobility in a moderately doped semiconductor depends on the temperature, carrier concentration and the applied electric field. so I want to know: How does mobility vary with electric field while ...
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1answer
191 views

How is EMI avoided inside of an IC?

I was re-watching this video about how CPUs are made and at the time of the video the link points to, I thought "Isn't there some EMI problems with all those transistor signals flying all over the ...
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2answers
181 views

How does a Schottky diode work?

There are no spare positive/negative charge carriers on the metal side of the diode, so the spare positive/negative charge carriers on the semiconductor side can not diffuse into the metal and ...
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2answers
74 views

Relation between drift velocity & conductivity of a doped semiconductor

Here is the problem, and I am stuck. When an electric field with strength \$1 \times 10^3 \text{V/cm}\$ is applied to a p-type uncompensated Si sample at room temperature, the electron drift ...
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1answer
119 views

How power system is designed for extreme small system, such as google contact lens?

I just read this news and got very curious: http://www.takepart.com/article/2014/07/23/goodbye-finger-pricking-how-googles-smart-contact-lens-really-helps-diabetics Google is designing "Google ...
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1answer
303 views

Why does Intel produce core i3, core i5 and core i7 processors; but not core i2, core i4 or core i6 processors? [closed]

Why does Intel produce core i3, core i5 and core i7 processors; but not core i2, core i4 or core i6 processors? What is the reason behind this?
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1answer
157 views

What is the meaning of biasing in electrical/electronics circuits? [duplicate]

What is the meaning of biasing in electrical/electronics circuits? What is the need for biasing in BJT/MOSFET? What will happen after biasing when we apply input signal(AC/DC)? Will biasing signal and ...
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1answer
111 views

What is difference? The name of IC's are punched or printed or stickered on top of it

I've seen in some IC's the name of it is 'printed' on the top side. But in some IC's the names are 'punched',they have impressions on the IC. And in some cases, a 'Sticker or a Label' has been ...
3
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2answers
187 views

Why does Intel looks so advanced compared to other foundries, engraving fineness-wise? [closed]

Latest chips from Intel were 22nm, and they are now targeting 14nm (coming in 2014 or 2015 it seems). On the other hand, Global Foundries or TSMC struggle since several years to go beyond the 28nm ...
0
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1answer
72 views

Semiconductor diode barrier potential

I have little confusion regarding barrier potential (or built-in voltage) and cut-in voltage of diode. Are these are same or what is the difference between built-in voltage and cut-in voltage in ...
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1answer
638 views

Where to find derivation of s'' (stability factor for beta) for BJTs?

I'm looking for the derivation of the formula for the stability factor (\$S''\$ or \$S(\beta)\$) of BJT bias circuits, particularly the ones with emitter resistance. The book I'm using says that the ...
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2answers
302 views

Flyback Diodes and Relays

I'm wanting to use a relay as a SPST switch, and I've noticed many designs incorporate a flyback diode. What instances are these needed and what are potential drawbacks, if any?
2
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1answer
298 views

Noticed something weird in derivation of relationship between ICBO and ICEO in BJTs

So I'm currently studying Electronic Devices and Circuit Theory by Boylestad and Nashelsky (11th ed.) and I'm confused as to how the relation between \$I_{CEO}\$ and \$I_{CBO}\$ is derived. So the ...
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1answer
92 views

Ideal diodes and applications

simulate this circuit – Schematic created using CircuitLab Question: The input signal V(s) is a square wave of \$\pm\$20V (peak) at 1Hz. Sketch the output waveform V(o). Clearly mark the ...
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3answers
217 views

Understanding the PN-Junction Built in Voltage

I don't like asking duplicate questions but I couldn't find one that was quite the same. I apologize if it is similar to another. TL;DR: How can a charge neutral substance have a potential? Why ...
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3answers
64 views

Avalanche breakdown voltage, how does it start?

I would like to learn about the avalanche effect. I understand what goes on in the avalance effect, but I can't understand how it starts. For the avalanche effect to start, an electron (the first) ...
5
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3answers
162 views

Given metal dimensions and material, is it possible to determine the maximum current that the structure can handle? [semiconductor processing]

I have a linewidth structure that has very low resistance. I want to know the maximum current that this structure can handle. Since the resistance of the metal is so low, it's hard to measure the ...
1
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1answer
203 views

Diode built-in voltage and barrier voltage (forward bias voltage) are they almost equal? how do they relate to each other?

I am little confused between the built in potential that is built up in the diode depletion region and the barrier voltage that needs to be applied across the PN junction to start conducting. My ...
2
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1answer
1k views

Comparison between MOSFET, MODFET, and MESFET?

I am taking a course on semiconductor physics and am learning about MOSFETs, MODFETs, and MESFETs. I know the general structural differences between each one. A MOSFET is a metal, oxide, and ...
1
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3answers
68 views

Transportation of holes

I was studying pn junctions and came across the concepts of diffusion currents. From what I understand is, when the junctions come together, since there is an excess of donors on the n side and an ...
2
votes
1answer
333 views

Why doesn't a capacitor connected to a MOSFET charge to VDD

If an nmos which has the gate and drain connected to VDD, and the source connected to a grounded capacitor, the nmos will start conducting and the capacitor will start charging as long as VDD > VTn ...
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2answers
119 views

Problem related to semiconductor?

Ok so this is the question along with its four option given in my text book I can't figure out what the answer should be as it is not stated that is the semiconductor forward biased or reverse ...
20
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3answers
1k views

Why isn't there a potential difference across a disconnected diode?

I know this question sounds silly, as if there was a potential difference a current would be created when the terminals are connected together and this would mean energy has come from somewhere. The ...
6
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1answer
869 views

Does MOSFET let current flow through source to drain as it allows it from drain to source?

Does a MOSFET allow current flow in reverse direction (i.e.; from source to drain)? I made a Google search, but couldn't find a clear statement about this matter. I have found this similar question, ...
3
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2answers
77 views

In a semiconductor, why is it said that holes also diffuse?

Let's say we have a p-type and an n-type semiconductor. I understand that the free electrons in the n-type semiconductor move to the p-type, but why is it said that the holes also move to the n-type ...
3
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2answers
201 views

Are BJTs used in modern integrated circuits to the same extent as MOSFETs?

On modern integrated circuits, are there as much BJT's on the chip as MOSFET transistor? If not, why?
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1answer
57 views

When does Direct Source-Drain tunneling become a problem?

Because of the probabilistic nature of quantum mechanics, direct source-drain tunneling is bound to happen as a result of CMOS scaling. The smaller the transistors become, the more tunneling occurs. ...
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2answers
206 views

What exactly is a potential barrier in transistors?

Here it says that: When a transistor is OFF, there exists a potential barrier between the source and the drain.. I don't know exactly what a potential barrier is. If I had to make an educated ...