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 the conduction state. Silicon, Germanium, 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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67 views

Why does the value of shunt resistor need to be very high for solar cell's greater efficiency?

In the circuit equivalent of a solar cell, shunt resistor is described as "The irregular polycrystalline lattice grain boundaries that resist to the flow of electrical current in the silicon ...
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56 views

Why does channel length modulation only occur in the saturation region?

As drain voltage is increased, the reverse bias across the drain-body junction also increases and thus the width of the junction should also increase which should deplete the channel length as well. ...
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Is saturation region defined for a “given” collector emitter voltage?

I have seen the traditonal saturation regions graphs (attached). The graph gives the impression that there is a huge region which is saturation region. Shouln't the saturation region be for a "...
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Does the collector voltage have to be greater than the emitter voltage by few tenths of a volt for an NPN transitor

For an NPN transistor, does the collector voltage have to be greater than the emitter voltage by few tenths of a volt for it to be in active state? If yes what is the reason? Also it says greater by a ...
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Node Technology in Modern Transistors

i was reading about the new 2nm chip IBM created and through some reading i learned that the "nm" part does not refer to the actual gate length like it did many years ago. Can anyone tell me ...
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How does the stored charge gets decayed when going from forward bias to zero bias?

In a pn junction diode when forward biased, excess electrons and holes get stored in p and n regions respectively. If we short the diode by connecting p,n terminals with a wire, how do these stored ...
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Maximum Typical and minimum into datasheets. What is the distribution?

What is the probability of having a component with the minimum and maximum specified value into the datasheet ? I suppose this follow a normal law and the typical value is the mean : Have a nice day !...
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What is exactly modeled by 'transit time' in SPICE diode model?

I'm trying to find a precise definition for the transit time parameter in SPICE diode model. What I think is the official documentation for standrad Berkeley SPICE diode model says the following ...
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Why is 'density' different for current?

Considering an N-type semiconductor, when we talk about carrier density, it means number of electrons per unit volume. But, when we define current density(J), it is measured as total current per unit ...
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Relation between forward bias and current in a diode

I have seen the VI graph to depict the relationship between forward bias and current. (left graph) and I think I get it. I have also seen another graph (right graph) to depict the relation between ...
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How can a Zener diode maintain a constant voltage?

A Zener diode in reverse bias more than breakdown starts conducting. If you increase the reverse bias: It conducts more i.e current in it increases The voltage across it remains same I think I get ...
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Capacitor as a ripple filter in the rectifier circuit - difference in charging and discharging time

Most of the times attached picture is used to depict the use of Capacitor as filter in the rectifier circuit. I guess, i understand the broad concept but I am struggling with the fact that charging ...
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GaN Vs SiC physic properties

Here is a table which shows the différence between GaN and SiC: I have no knowledge about physics of components. I have just some bases. In the above table I do not see real difference between SiC ...
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Is it a bug in the design of a low side UCC27524A, and 2EDN7424 gate driver if it doesn't use VDD capacitor?

I am using low-side TI and Infineon gate drivers. If I don't use a VDD capacitor, then there is a glitch in the output waveform as shown in the figures. It seems it's the designer's or layout problem ...
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Semiconductor Database for damage to electronics

My colleague, who has experience with EMP (electromagnetic pulse) analysis, mentioned a database for electronics (IC, discrete circuits, semiconductors devices) that contained the information on the &...
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In this schematic, where is the depleted layer once voltage is applied to the the sensor?

In the following schematic from https://cds.cern.ch/record/2717863/files/CERN-THESIS-2019-340.pdf the sensor is the top part, the readout electronic is the bottom. Once we have applied an electric ...
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Does the current change in a Zener diode if I we increase the voltage

Zener diodes work in reverse bias in the breakdown region. At breakdown voltage, high current flows. I get till here. I want to know what happens if I increase the voltage after breakdown. Is there an ...
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86 views

Why is the N side thinner than the P side in a photodiode?

I have been reading that a photodiode is built by sandwiching a very thin N type semiconductor togther with a thicker P type. Why is that so?
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diode circuit without a voltage source

Will there be any current in the given circuit? If current exists then why do they exist and what will be the forward and reverse current and voltage(across the diode)? As a student of Physics I will ...
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246 views

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 ...
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Is it possible to connect each and every pin of two IC's together and increase perfomance?

I am a newbie to electronics. I have a crazy idea in my mind to create a PC with 32 bit microcontrollers. I chose the ATSAMV71J20 chip. The processor has a maximum CPU speed of 300MHz. If I connect ...
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Why can't conductors be used in making ICs (integrated circuits) instead of semiconductors? [closed]

I really wanted to ask why we can not control flow of electrons in conductors. Can I not say if a current is flowing in a conductor it is 1 and when I disconnect the supply it is 0. Can you elaborate ...
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What is the exact meaning of 0.7V voltage drop in a forward-biased diode?

this question is partially (but not totally) discussed here: Why do diodes have a voltage drop? Does the power drop on a diode become entirely heat? The conclusion is that, in a forward-biased diode ...
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Why does conductivity depend only on electrons in conductors but in semiconductors depends on holes and electrons?

why does conductivity is calculated as: conductivity = e.n.Un e : electron charge n : electron concentration Un : electron mobility but in intrinsic semiconductors conductivity = e.n.(Un+Up) Why does ...
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Current flow between metal and piece of pure silicon

This is a very theoretical question and mainly just for my understanding for current flow. Let's say I have a DC voltage source. I use two metal wires to connect my DC voltage source across a piece of ...
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102 views

Zener Diodes: How are different voltage drops achieved

How do semiconductor makers make zener diodes with a fairly wide range of voltage drops? In particular I'm curious how they get small increments - 3.3V, 3.6V 3.9V, 4.2V, 4.8V etc as I thought the ...
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Is there any specific application for an indirect band gap semiconductor?

I know that direct band gap semiconductors are very attractive for optical emission, and even though indirect band gap are used as well, I keep wondering: is there any technology that specifically ...
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Part Identification, Board says C32 but it looks nothing like a capacitor and has 6/9 marking on it

First, I understand that you have to remove the components to fault find but this is just something to play with. It's an internal HDD SATA adapter to USB3 with additional 12VDC for 3.5" HDDS. It ...
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3answers
346 views

Need to increase the amplitude of op-amp output

I'm using this circuit to measure the RPM of a DISC rotating at 24000 rpm. This circuit is working fine. But the problem is with amplitude. It should be of 4.2V, but actually is of 2V as shown in ...
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What are some reasons for hand painted dots on chips?

I've seen lots of products with hand painted dots or markings on chips, what do they often mean? Obviously I understand everybody has their own reasons but could it be an industry common practice for ...
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How to convert spontaneous emission into stimulated?

I have a semiconductor diode that has spontaneous emission (LED). The question is what can I change in the fabrication of the diode to improve its performance such that the diode gains a stimulated ...
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Calculating chip junction temperature based on case temperature

As far as I know one can calculate a chip’s (Diode, Transistor..) junction temperature rise with the consumed power and the thermal resistance Rth. Is there a way to calculate the junction ...
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Why is the saturation velocity for holes and electrons comparable?

In a semiconductor like GaAs, the saturation velocity for both holes and electrons is on the order of \$10^7\$ cm/s. However, under lower electric fields E, the drift velocity of electrons is much ...
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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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In semiconductor physics, how can we know which units to use for Boltzmann's constant?

I'm working through Example 3.9 from Sima Dimitrijev's Principles of Semiconductor Devices textbook, and I'm not sure how to know which units to use for k in solving for \$v_{th}\$ in part a. The ...
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Depletion Region Capacitance in MOSFET

Hi, I would like to ask about the behavior of a MOSFET as a capacitor, particularly at the onset of inversion/weak inversion - see Fig 2.6(c) At this stage in Fig 2.6(c), there is positive charge at ...
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Is this question wrong? possible to calculate gain without beta or Ic given? [closed]

How to proceed with this question? I can't think from where to start.
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MOSFET current at very low temperature (4K)

I am trying to model the current at low T. To do so I need to compute the integral between the fermid diract statistic and the conductivity, with respect to energy. My problem is that I cannot ...
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How is the asymmetry of a Schottky diode obtained?

A Schottky diode is constructed with two metal conductors bonded to a doped semiconductor. One of the metal-semiconductor junctions is a Schottky contact, and the other metal-semiconductor junction is ...
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In an intrinsic semiconductor, are there the same number of carrier electrons and holes? Or this is just exclusive for silicon?

I am working with some polymers that behave like semiconductors when they are plugged into the current. I am calculating the mobility of these polymers and I need the value of the current density (J) ...
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36 views

Measuring capacitance of Metal-Insulator-Semiconductor (MIS) structure with LCR meter

I can not get my head around what a LCR meter measures. My LCR meter measures my device (MIS) which is displayed as C_p and G_p (other components can be neglected). My LCR meter displays C_p, G_p, the ...
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pn Junction - Depletion Layer

From the textbook that is prescribed for my course as well as on google, I have been told due to the diffusion of electron from n->p and the holes from p->n, positive ions are left in the n-...
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Semiconductors out of equilibrium

In connecting two separated materials with different Fermi levels we have carrier flow. Do electrons and holes always move in opposite directions?
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Why can't current flow in this circuit?

Boylested says that during the positive voltage half cycle diode D2 is cut off. But why can't there exist a current flowing through the outer loop via C1, the secondary of transformer coil, C2, and D2 ...
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Explanation for drift current

My question is why the concept of drift current or movement of minority charges is necessary while the pn-junction is formed. So drift current was explained to me in more or less this way As the ...
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381 views

Inability to forward bias diode in a simple circuit

I am struggling with forward biasing a diode in the circuit in the attached. All the wires are attached properly, as there is continuity. The diode drops only 0.400V with a 9 V battery connected, the ...
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What happens when an LED burns out? [duplicate]

When an LED is burned out, specifically which part is burned out? Is it the semiconductor or the wires? Can we use a burned out LED to generate electricity?
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Current-voltage characteristics of silicon carbide luminescence

I am currently studying the textbook Light-Emitting Diodes (3rd Edition) by E. Fred Schubert. Chapter 1.2 Henry Round's demonstration of the first LED says the following: The mechanism of light ...
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How temperature difference does not affect transistors in CPUs?

Recently I learned about semi-conductors and some devices. Today I watched a video on youtube about a guy overclocking a cpu to 7.0 ghz, while cooling it with liquid nitrogen to -192 celsius degrees. ...
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Why will electrons move from hole to hole in the p type at forward bias, but not from hole to n type at reverse bias?

This question is about a diode with a p type and an n type. At the forward bias the electrons from the n type to the p type and from hole to hole in the p type. My questions are these: At the forward ...

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