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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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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56 views

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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33 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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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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FET source body connected to the same potential

I have learn that the FET looks like this: However industrial FETs are not built like that.The source and the substrate have common potential.However if the source and substrate have common potential ...
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How would the total charge density of n type semiconductor formula change after applying bias?

The following formula is the total charge density of n type semiconductor. When we applied, lets say, 2 V bias to this semiconductor, how would this formula change? (Nc: effective density of states ...
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Qualitative explaination of Output Characteristic of Transistor (BJT) using Depletion layer between Collector and Base

From my understanding, The diffusion layer at a p-n junction is an equilibrium of two opposing forces on charge carriers due to 2 forces - Concentration Gradient and Electric Field caused by Bias and ...
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Transistor: Getting “incorrect” graph for input voltage to output voltage

I tried drawing the graph of \$v_o\$ vs \$v_i\$ for a bipolar junction transistor. I used the below setup (common emitter:) By design of how the base is a small part compared to others, \$I_b <<...
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Calculating effective mass of electron from energy band diagram

How can I calculate the effective mass of electron in the conduction band of silicon with the approximation that they are free, from its energy band diagram by my hand - not software or something else?...
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1answer
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Is the current in reverse biased PN junction due to drift or diffusion?

Wikipedia says The saturation current (or scale current), more accurately the reverse saturation current, is that part of the reverse current in a semiconductor diode caused by diffusion of minority ...
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How point-contact transistor work?

In December 1947 Bardeen, Brattain and Shockey introduced a device which is considered to be the first transistor. This transistor was point-contact device. So, it used metal-semiconductor junctions. ...
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If leakage current for a diode is 20μA at 20 degrees celsius, what is its value at 40 degrees celsius?

These are the only values provided so I'm not sure how to go about this question. Any help would be greatly appreciated
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Confusion regarding the I-V characteristics of a solar cell

We know that I-V characteristics of a solar cell are described through the following equation : This equation can be translated graphically to the following (ideal) circuit : Now according to the ...
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how to calculate doping concentration in the base

how to calculate doping concentration in the base, and emitter, collector of SiC ? In the neamen book dont teach that. just propose the constant number. so can you help me? I hope to calculate NB, NC, ...
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IGBT modelling from datasheet

how to model igbt from the APT150GN120J datasheet. ...
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Can I find a file of a microchip for a 1:100000+ version on a 3D printing machine?

It would be cool to replicate a semiconductor microchip on a 3D printer, i.e. a C64, an intel processor, an AMD processor. Can you think of a kind of map file format which graphs many transistors and ...
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Simulating circuit TINA TI

For my assignment I got to run a transient analysis for the duration of 5 periods of sinusoidal input voltage and display the input voltage (ac + dc) and the output voltage on the RL component. Used ...
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TINA TI Zener diode scheme

I've encountered some problems while trying to get this scheme. I don't think graph should look like this. What I am trying is to draw a diagram to record the static characteristic of the Zener diode ...
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Cut-off frequency of a LED

I'm trying to solve this problem: A GaAs LED is at \$ 300 K \$ when the current density is 1000 \$A/cm^2\$ . The width of the active region is \$ 1 µm \$. Assume that, for that current, we are in the ...
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Mobility of electrons vs holes in semiconductors (intrinsic vs extrinsic)

I was reading my class notes and it was written that electrons are more mobile than holes because the effective mass of electrons are lower than that of holes. (μ=eτ/m*) I checked online to find the ...
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Current Voltage Relation in Mosfet

I have the following problem We want to find the graphical current-voltage relationship for both the mosfets on the left. The only difference I can actually spot is the doping of the body of the ...
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Why do n-type materials have a smaller conduction energy band?

I looked at "Why does a p-type conduction band have higher energy then n-type conduction band in a p-n junction?" and am still confused. From the image above we can see that the conduction ...
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Which semiconductors are good candidates for constructing a CPU? [closed]

Wikipedia offers an excellent list of semiconductor materials but does not include which can be used to create integrated circuits or even logic transistors (PNP or NPN). The Integrated Circuit page ...
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How drift current is independent of bias voltage in semiconductors?

According to my textbook: The drift current is relatively insensitive to the height of the potential barrier. The reason for this anomaly is the fact that the drift current s limited not by how fast ...
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BJT DC Circuit Analysis

Say we have this circuit below: And we were tasked to: a.) Get Ve and Vc when Vb=0v. b.) To find what Vb will make the transistor be in the cutoff and saturation region. The following are given: α ...
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BJT Active Region - Biasing of BE and BC junction

I am having trouble understanding why the BC junction is considered to be reversed biased in these two models. The way I see it, the base looks to be in a higher potential than the collector junction ...
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Dependency of Collector current in common base transistor(active region)

I just started reading about transistors from book "Microelectronics circuits"by Sedra/Smith, This is written in book which I don't understand, any help would be much appreciated For forward ...
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How are opcodes decoded at hardware level in any controller?

I know that any compiler will convert human readable code to binary. This binary code is a opcode which has instruction+operands in it. I do not understand how this opcode is decoded at hardware level....
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Mechanism of conversion of electrical energy to EM energy in LEDs

I've always been intrigued that electrical energy can just disappear out of a circuit 'into the aether' as RF. Of course thinking about it, some energy 'vanishes' as EM radiation even in a filament ...
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Light coming from the room influencing TV

Inside the TV Remote we have a LED of infrared light which sends commands to the TV. Isn't it influenced by the light of the room(if any?).I thought if an electron in the valence band absorbs a photon ...
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Need of semiconductor instead of conductors for changing conductivity

Is changing conductivity is one of the reason to use semiconductors? When we can change conductivity of metals(by some means) then why do we need semiconductors instead in most of the electronic ...
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247 views

Gate leakage current for a JFET?

I'm really confused about how JFETs work. JFETS are usually significantly higher doped donor xor acceptor atoms. My professor mentioned that MOSFETs usually have an oxide in between the the metal and ...
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Why are PIN junctions better for solar cells than PN junctions?

In lecture today my professor mentioned that PIN junction make better solar cells than PN junctions. Why is this true? The PIN junction will have a wider depletion region which means it'll have a ...
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What does the fermi-level increase in reverse-bias?

Fermi-level tells us the probability of finding an electron at 50%. When you look at an energy band diagram in reverse-bias you can see the Fermi-level increases in the p-type semi-conductor. Why does ...
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In an energy band diagram why is the valance band in the p-type have more energy then n-type?

I am having trouble understanding energy band diagrams. In an energy band diagram of a semi-conductor during equilibrium the valence band of the p-type is higher then n-type meaning electrons in the ...
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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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Why does a MOSFET threshold Voltage not increase when the channel length and/or oxide layer is increased?

I am reading through Fundamentals of Microelectronics by Behzad Razavi. I am okay with the information provided in the images, and understand that if the channel length or oxide layer is increased, ...
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Electric field throughout a semiconductor

Suppose I have a semiconductor bar of length 2mm and I am applying a potential difference of 2V across it. Will the magnitude of electric field be same throughout the bar OR will it be different at ...

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