All Questions
Tagged with semiconductor-physics thermodynamics
49
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How can red LEDs still give a faint glow at a voltage of only 1.4V? [duplicate]
How can a red LED work at a voltage of only $1.4{\rm V}$? Red photons have an energy of $1.77{\rm V}$ if we use $\lambda = 0.7\mu\text{m}$ in the relation:
$$ E = \hbar \omega = \frac{2\pi\hbar c}{\...
- 4,913
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Why would a depletion "layer" form in a PN junction?
I understand that electrons diffuse from the N to the P region due to the concentration difference. This diffusion of electrons creates an electric field opposing further diffusion.
What I don't ...
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2
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Thermal Smearing in Josephson Junction
I'm basically trying to simulate a josephson junction at a particular temperature. As per some of the plots I could find, the rise in temperature leads to a rounding of the I - V curve. I was ...
- 143
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Fermi-Dirac integrals of different orders
Which physical quantities are related to the Fermi-Dirac integrals of different orders?
If fermi-dirac integral, write like this:
$$F_\xi(\eta_c) = \frac{1}{\Gamma(\xi+1)} \int_{0}^{\infty} \frac{x^{\...
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2
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Does diffusion current "consume" thermal energy?
My (possibly erroneous) understanding of solid state physic has led me to the belief that diffusion current may "consume" thermal energy.
Here is my (possibly erroneous) understanding. When ...
- 2,882
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What is the relationship between the applied reverse bias in a p-n junction to the band gap of the semiconductor?
Consider a p-n junction under reverse bias. The difference in the Fermi Energy of the p-side and the n-side is $qV_r$ where $q$ is the elementary charge, and $V_r$ is the applied reverse voltage. What ...
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Would a diode more ideal than Shockley diode equation violate the second law of thermodynamics?
The Shockley diode equation describes the behavior of all diodes extremely well. Semiconductor p-n diodes and Schottky diodes are described by the very same equation. Furthermore, it applies to light ...
- 123
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Definition of Hall's current
Dear fellow physicists!
I come to you with a question regarding the definiton of the Hall current.
The only sentence close to definition of this concept, I have found after extensive search on the ...
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63
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How does surface area relate to the Seebeck Equation?
I know that the equation is
$$V = (S_B-S_A)(T_2-T_1),$$ but surely this output voltage must be proportional to the surface area (and probably thickness) of the Peltier device. What is the formula that ...
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Infrared solar pannels and thermodynamics
I was wondering if we could use background radiation to produce electricity (even a tiny amount). However, I've read somewhere that solar panels absorbing infrared (and lower frequencies photons) ...
- 213
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Proof that Fermi level is constant throughout a system in thermal equilibrium
The explainations I saw:
The one I was referring to in this question. I described why I find this explaination not satisfying in the question.
Consider $2$ systems in contact. The rate of particles ...
- 513
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67
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What mechanism causes failure in a BJT when collector current is exceeded? [closed]
Does exceeding the rated collector current of a BJT cause the device to fail because it suddenly heats up very fast? Or is there some other reason?
If the reason is heat, I'm wondering if I can exceed ...
- 175
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65
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Why does the depletion region in a reverse biased diode grow?
From what I understand, at the pn-junction of a diode, electrons diffuse from the n-region into the p-region until the resulting electric field grows large enough to stop any further flow of electrons....
6
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Photovoltaic cells vs. Second law of thermodynamics?
Question: How do photovoltaic cells actually work?
Here is the standard explanation:
Photovoltaic cells comprise of an N-P silicon junction. The terminals are in electrical contact with the N and P ...
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Can an LED emit photons with energy (in $\rm eV$) larger than the voltage drop across it (in $\rm V$)?
I recently had a discussion with someone who told me that they have a UVC (260 nm - 270 nm) LED with a forward voltage of 3.3 V. I told them that this must be impossible, because an electron dropping ...
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