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411
bio website daniel.farrell.name
location Tokyo, Japan
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visits member for 4 years, 6 months
seen 21 hours ago

I know how to use the grey square -- do you?


2d
revised What is the total internal reflection?
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2d
answered What is the total internal reflection?
2d
comment How will open-circuit voltage affect the Fermi Level Difference
This is not specific enough to answer. What materials? What are the Fermi-levels locations? When materials come into contact the Fermi-levels align until a space charge halts any further change.
2d
comment Does light ever experiences acceleration?
Never thought about it like that before, how curious!
Jul
29
comment What causes this IR emission in UV 365nm LED?
How did you remove the possibility of grating harmonics? What does your spectrometer setup look like?
Jul
29
answered Why is Fermi-Dirac type of distribution used in semiconductors?
Jul
26
revised Nature of photoluminescence at a semiconductor heterojunction
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Jul
26
answered Nature of photoluminescence at a semiconductor heterojunction
Jul
25
comment Why do particles in a medium have different speeds?
Statistical mechanics can answer this. The maxwell Boltzmann distribution of velocities of an ideal gas describes a system that has come into equilibrium with it's degrees of freedom. Moreover the particles are distributed ergodically in phase space and thus represent the lowest energy/maximum entropy configuration of these particles. My hunch is that a uniform distribution of velocities could indeed have the same total energy but will also have lower entropy and is thus an unstable configuration. As for a more mechanical description I need to think harder! Great question a big +1 from me.
Jul
25
comment Why are mediums always represented as straight and parallel lines in Ray optics?
This diagram is teaching you the very important concept of refraction. Refraction also happens on curved surfaces but the additional complexity will obscure the same underlying mechanism.
Jun
13
comment Asymmetric photoluminescence spectra
Google is your friend. encrypted.google.com/…
Jun
12
answered Asymmetric photoluminescence spectra
Jun
12
answered Reflection of light at a microscopic level
May
10
comment How do the Fermi level, HOMO and LUMO change with doping?
If you provide some references that mention constant fermi-level we can probably tease this apart.
May
9
comment How do the Fermi level, HOMO and LUMO change with doping?
Why is the Fermi level constant with doping? This is the level of 50% occupancy; this should change with doping.
May
8
comment Steady State Solution for Carrier Concentration of Intrinsic Silicon in an Electric Field
This is pretty difficult. You also need to solve the Poisson equation to provide $E(x)$. The standard approach is to user the Boltzmann approximation and change variables to from carrier densities to quasi-Fermi-levels. Then you need to discretise the equations (FD, FVM or FEM) and include some form of exponential fitting to keep the equations stable when the Peclet's number is large. Then for accurate solutions some form of adaptive mesh refinement should be used. All in all a very tricky problem! Take a look at the pn-junction solvers on nanohub.org they might get you started.
May
5
answered Bimolecular recombination in few words
May
4
comment Diodes in AC current
If you move it very quickly you will still be able to see the on-off cycle at 60Hz as streaks.
May
4
comment Is refraction of light a thermodynamic process?
Total internal reflection has a thermodynamic/statistical interpretation: is a mismatch between the plentiful internal optical modes and the fewer modes available in the less optically dense material across the interface. I have not thought about a similar analogue for refraction but I imagine the same mental model could be used to describe this process.
May
4
answered What are the purposes of slits inside a spectrometer (Czerny-Turner)?