Questions tagged [semiconductors]
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 their conduction state. Silicon, Germanium, and GaAs are some usual materials. The term is also used to speak about devices that are made from such materials, for example, a processor from Intel can be called a semiconductor.
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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 ...
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Can a thyristor be built from two transistors?
Supposedly, an SCR/thyristor is just a simple, four layer PNPN semiconductor.
If that's the case..
When a circuit calls for a SCR/thyristor, and there isn't one available, can it be substituted by (...
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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 ...
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Why is the temperature range of industrial and military products so high?
From Wikipedia the common temperature range for electrical components is:
Commercial: 0 to 70 °C
Industrial: -40 to 85 °C
Military: -55 to 125 °C
I can understand the lower part (-40°C and -55°C) ...
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How should I understand the intrinsic body diode inside a MOSFET?
I know there is an intrinsic body diode inside all the MOSFETs, but I'm confused about the reason why it's there. I've searched the articles but can't find a good explanation for it. Can anyone use ...
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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, ...
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Transistor(BJT) as Two Diodes
With reference to Vasiliy's answer on this question
Why can't two series-connected diodes act as a BJT?
"excess electrons from the P side of the forward biased diode can not be swept to the P ...
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What is the physical model for energy flow in or around a lossless conductor during transient analysis? (Veritasium Electricity in Wires)
Context
Veritasium - The Big Misconception About Electricity - Energy Doesn't Flow in Wires
Note I do not agree with the answer (D) given by Veritasium which is only plausible if any tiny current ...
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Why does a p-type conduction band have higher energy then n-type conduction band in a p-n junction?
In an energy band diagram that represents the p-n junction (during equilibrium) the p-type conduction band has greater energy then an n-type conduction band. Why does the p-type have greater energy ...
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MOSFET common source amplifier output impedance calculation
What I've read in microelectronic texts like Prof's Razavi's Fundamentals of Microelectronics is that for calculating output impedance, one has to make all independent sources 0, i.e., short all ...
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What is silicon germanium (SiGe)?
I've heard that SiGe chips can be faster than ordinary silicon chips.
What is SiGe and why is it faster than ordinary silicon?
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Where are the depletion PMOS transistors?
In school, I was taught about PMOS and NMOS transistors, and about enhancement- and depletion-mode transistors. Here's the short version of what I understand:
Enhancement means that the channel is ...
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Resistance of a semiconductor diode
When we calculate the dynamic resistance \$r=(\frac{dv}{dI})\$, for any n-p junction, how is it different from the normal resistance \$R=\frac VI\$? Does the equation for the voltage drop (The fermi ...
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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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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?
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Confusing regarding measuring barrier potential of a pn junction using a voltmeter
I have been trying to understand why we can't measure the Barrier potential existing in an unbiased pn diode but on seeing the answers I am quite confused.
There seems to be two answers to this ...
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Equivalent circuit of a photodiode
What can I learn from an equivalent circuit model of photodiode like the following?
I've actually gone the whole way beginning from doping semiconductors through each noise term to the amplification ...
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Formula for efficiency of half wave rectifier
I came across this formula for rectification efficiency of half wave rectifier:
η= (40.6 *resistance of load resistor )/ (resistance of load resistor+ resistance of secondary of transformer + ...
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How could the Gate-Source potential difference be neglected?
I’ve been reading the book
Electronic Principles by Malvino
In the Voltage-Divider bias section of JFET, if gate current is negligible then how did Gate Voltage attain a negative value, given Vdd ...
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What happens to the semiconductor in an LED when it is given voltage that it cannot handle?
Let us suppose we have an LED with the allowed voltage range of 1.5V to 4.5V and we gave it somewhat 12V. Now we know that the LED will instantly stop forever. But I want to know what will happen to ...
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A problem from shift in the fermi energy level
if the effective mass of holes in a semiconductor is 5 times that of the electron, at what temperature would the fermi level shift by 15% from the middle of the forbidden energy band? (given that, eg =...
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Why would a Intel 8080 chip be destroyed if +12 V is connected before −5 V?
The Intel 8080 is a classic microprocessor released in 1974, fabricated using an enhancement-mode NMOS process, and shows various unique characteristics related to this process, such as the ...
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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 ...
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Why do electrons move faster than holes in a semiconductor?
When an electron leaves, then only a hole is created, and when another electron fills it, then only the hole moves, so in that way, both should conduct current at the same speed. Yet I've been told ...
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Why won't this DIY transistor attempt conduct
I've been trying to make a crude transistor device at home. So far I have not been successful. My electrical understanding is next to non existent other than what I've learned in the last 3 months ...
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Exotic semiconductors for fast digital ASIC
I am researching exotic semiconductors for a digital ASIC with a few million logic gates which should run as fast as possible within a $30 million budget. (Specifically, I need to do a single fully-...
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Pre-biased Bipolar Transistor (BJT) Tradeoffs
If you go to the Discrete Semiconductor category on Mouser.com, there is a section for "Bipolar Transistors - Pre-Biased".
Is this as simple as including a resistor in series with the base?
Are there ...
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E-K diagram in case of semiconductors
I am currently studying solid state electronic devices and want to build my concept in this subject. Can anyone explain to me what is E-k Diagram and what is its significance?
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Mosfet Depletion Region?
I'm reading about Semiconductor Physics (Semiconductor - Physics and Technology), and I'm confused on one part of MOSFETs.
I understand the PN junction (FINALLY!) and all the basic level stuff. But I'...
user3073
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Series connection of diode and resistor. Why is there a constant voltage across the diode?
So I know that a diode can be described using the Shockley equation and after a certain voltage, the diode current begins to increase rapidly. The nominal 0.7 volts. I also know that this voltage ...
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How is a semiconductor electrically neutral?
I'm in the process of learning how transistors works, which starts with understanding how doping is used to create n-type and p-type semiconductor materials.
All the resources I've read sort of ...
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In a JFET, is the gate *always* connected to the bulk/substrate?
In a JFET, is the gate always connected to the bulk/substrate ?
Or is there "no rule" (sometimes it is, sometimes it is not)?
And what about the case of the MOSFET ?
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What is the reason of difference in distributed gate thyristor design
As in the pictures, they use different designs (current rate, voltage rate etc. are same.)
What is difference between these two designs?
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Why "substrate" is exposed through a "do not connect" pin at all?
I've were reading through MOC3041 opto-isolated triac when I noticed this part:
"Substrate". It's also repeated later on one page down further, but there's no explanation. I guess that might be the ...
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How does it work when multiple companies sell the same IC? [closed]
Very common ICs are sold by many manufacturers, for example let's say the TL07x range (which is vintage, but does demonstrate the case).
Inspecting datasheets of two manufacturers, TI and Diodes Inc,...
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Can Tesla valve concept work for electrons?
This is a Tesla valve. It works by diverting liquid or gas back on itself when it is flown in one direction and allowing a smooth flow in the other direction.
Can the same concept be used to create a ...
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Modelling and simulating multiple-collector/emitter BJTs
I occasionally like to try to understand how well-known integrated circuits work by building them up in a simulator and observing how they respond to changing conditions. However, I keep coming across ...
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Doping of pure semiconductors
When adding extra electrons to pure silicon in a conduction band, the extra electrons will occupy a donor level below the conduction band (we get n-type), as shown here:
When adding electron-deficient ...
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Measuring barrier potential of a pn junction using a voltmeter
The image above is from the book "The Electronics companion". Can someone please explain why the barrier potential of a pn junction cannot be measured due to the presence of the contact potential?
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Understanding reverse biased PN junction
I'm trying to understand a reverse biased PN junction, conceptually. For reference, I'll adopt the convention that the P-type is on the left, and N-type is on the right. So without a bias, the ...
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Orientaion Flat on Semiconductor Wafer
On semiconductor wafers there is a straight line, which is called Orientation Flat.
What exactly are these and how they are formed?
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Why reverse connected MOSFET start to turn on at Vgs<Vth?
The circuit shown below is implemented using two AO3400 N-MOSFETs.
AO4300 datasheet here.
The right-hand MOSFET is connected with normal polarity (Vds is positive),
while the left-hand MOSFET is ...
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Connecting phototriac substrate to adjacent pins
For a regulatory exercise I am analyzing the result of a short fault between a phototriac's substrate (MOC3023) and its anodes (one at a time). The datasheet warns ...
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Identifying parts of a transistor die
In books, I have studied that in a Transistor, the Base is the layer sandwiched in between Collector an Emitter. Wikipedia also mentions that
"The base is physically located between the emitter ...
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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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Does diffusion current cause drift current?
I was studying about currents in an injected semiconductor (by illumination) from Integrated Electronics by Millman and Halkias. They consider the diffusion hole current in an injected n-type open-...
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Why aren't semiconductor wafers diced into triangles?
Semiconductor wafers are circular, and usually they are divided into squares or rectangles. However it's more efficient to pack triangles into circles than it is rectangles, so less wafer area would ...
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What are the ratings of vintage Selenium Rectifier B20/16-2,4?
Sort-of a follow-up to How to ground a vintage device that was powered without a ground? in that the device is the same.
I finally took the leap and opened up the old charger (depicted in the linked ...
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Why were bipolar junction transistors (BJTs) better than metal oxide semiconductor field effect transistors (MOSFETs) in the past? [closed]
I know that MOSFETs are used much more in industry than BJTs at the present, but I heard that performance of BJTs was better than that of MOSFETs in the past.
Can you tell me why?
Additionally, where ...
user284276
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Why Collector-to-Base currents ratio in a BJT transistor is always greater than 1?
In fact, this question has been asked on the EE site, but it's not well-answered. I suppose it might be more on-topic here.
According to this answer:
Note that the holes injected into Emitter are ...
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