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11

Any good book in Semiconductor Physics will have a description of the k.p method. Try Fundamentals of Semiconductor Physics by Peter Yu and Manuel Cardona. Another reference for Kane Model and EFA are chapters 2 and 3 of "Wave Mechanics Applied to Semiconductor Heterostructures" by Gerald Bastard. If you want a more mathematically/group theory oriented ...


8

Yes, your interpretation heuristically makes sense. As you may already know, as a consequence of Heisenberg's uncertainty principle, that an electron has a wave and particle nature. When you think of the wave nature of single particle states you are talking about Bloch states. When you're thinking about the particle nature you are talking about Wannier ...


7

In calculating the electron dispersion you probably obtained the diagonalized Hamiltonian in the momentum space $$ H=\sum_\mathbf{k}\left[c^{\dagger}_{\mathbf{k}A},c^{\dagger}_{\mathbf{k}B}\right]\left[\begin{array}{cc}0 & \Delta(\mathbf{k})\\ \Delta^{\dagger}(\mathbf{k}) &0\end{array}\right]\left[\begin{array}{c}c_{\mathbf{k}A} \\ ...


7

The absence of a material in a volume embedded into a larger volume that is fully filled by the material is always known as the hole. For example, look at this hole in soil. In semiconductors, the "soil" is replaced by the semiconductor material itself, with the right number of electrons per nucleus to make it neutral. So if there is an electron missing ...


6

You might find the Yahoo "home_transistor" group a useful resource. There's also a series of videos on YouTube by Jeri Ellsworth including some where she makes transistors. In one, in particular, she takes the crystal out of a germanium point-contact diode and turns the crystal into a point-contact transistor (much like the Bell Labs transistor.) There ...


6

The moore's (empirical) "law" states that the number of transistors in a chip increases exponentially (doubles every 2 years). So the question is : is there a hard limit in the number of transistors in a chip? Or, in other words : Are there limits on the size of a chip and on the size of transistors? Indeed there are (almost). The matter is made of atoms, ...


5

The key difference between a Zener diode and a normal diode is that the Zener diode has a low breakdown voltage - typically in the few volts range. The breakdown voltage is low because the heavy doping means the depletion layer is very thin, and even at a low voltage the field strength over this thin depletion layer is very high. With a conventional diode ...


4

The convention is that current flows in an electrical circuit from positive to negative. This was decided before electrons were discovered and before they were discovered to be negatively charged. You can identically consider the flow of electrical charge as either the movement of a negative electron from left to right, or the movement of the empty place ...


4

Not really an expert on solid state physics, and I'm prepared to look an idiot here - but I don't think it's the low temperatures that help. By overclocking a CPU 5.5Ghz you are almost doubling the power consumption and hence the dissipation. A large reduction in the temperature of the cold site of the heat sink helps it remove twice as much power while ...


4

The $A/W$ units refer to the current (in Ampère) produced per Watt of light incident on the photodiode. This current-production happens when the diode operates in the so-called photoconductive mode. Since your question wasn't on the inner workings of a photodiode, I won't expand on this, but Wikipedia contains some more information if desired.


4

It's difficult to know for sure without having access to the Thouless paper that you mentioned. However, in my own research field we sometimes talk about two processes called tunnelling and hopping, that are distinguished as follows. Tunnelling is a coherent process in which electrons move from one lattice site to another, maintaining a definite phase ...


4

Well, the answer is yes and no. The band inversion between the $s$-like (conduction) band $\Gamma_6$ and $p$-like (valence) band $\Gamma_8$ in HgTe is primarily responsible for its topologically nontrivial band structure. The bulk band structure of HgTe with (right) and without (left) spin-orbit coupling is shown in the figure below. There are a total of ...


4

From "The Transistor, A Semi-Conductor Triode", by J. Bardeen and W. H. Brattain, Phys Rev. 74(2), 230-231 (1948): "The device consists of three electrodes placed on a block of germanium as shown schematically in Fig. 1. Two, called the emitter and collector, are of the point-contact rectifier type and are placed in close proximity (separation ~0.005 to ...


4

Modern processors are built from CMOS technology. These digital circuits consume relatively little current when sitting in one state or the other. However, there is some inevitable capacitance on every node. When the output of a digital gate changes state, that capacitance is charged or discharged, which means current has to flow. The total average ...


3

I should see the whole article to give a proper conclusion, but I can tell you this from my experience as an experimental solid state physicist: When you are doing contact measurements and you have unusual properties, e.g. non-ohmic transport or dielectric response, it is possible that these unusual properties are artifact, that is not due to bulk of the ...


3

A quick answer: Imagine an array of billiard balls with one missing in the middle of the array; there is a "hole" where the billiard ball is missing. For this hole to "move", a billiard ball must move into that position, leaving a hole at the ball's previous position. Since, in fact, the hole movement is entirely equivalent to the billiard ball movement, ...


3

The main effect of an electromagnetic wave is basically that the electric field in the electromagnetic wave shoves charged particles around (ions and/or electrons). That's called "Electric dipole coupling". Electric dipole coupling is almost always much stronger than other effects of the electromagnetic wave. For example, the electromagnetic wave has a ...


3

The temperature $T$ plays a passive spectator role, so let us leave it out of the notation. Then the Taylor expansion of $R(n,p)$ at the point $(n,p)=(0,0)$ reads $$ R(n,p)~=~ R(0,0)+ R_n(0,0) n + R_p(0,0) p $$ $$+ \frac{1}{2}R_{nn}(0,0) n^2 + \frac{1}{2}R_{pp}(0,0) p^2+ R_{np}(0,0) np $$ $$+ {\rm third~order~and~higher~terms}, $$ where the sub-indices ...


3

If you consider a homogeneous piece of silicon the total flow of electrons through it is: $$ I = \frac{U}{R} = n \mu \frac{S}{d} U $$ where $R$ - the resistance of the piece, $U$ - external voltage applied to it. The resistance depends on: $n$ - the concentration of electrons (number of electrons per m$^3$), $\mu$ - the mobility of electrons (ratio of ...


3

Some observations: in diodes, the recombination time is of order a nanosecond. It's as fast for similar materials with a high carrier density. The time will depend on the density but also other things and I am not aware of a simple universal formula. It's useful to know that the intra-band collisions that bring the bands into their well-known distributions ...


3

Because they do not emit light. And they do not emit light because: massless photon has (almost) zero momentum. In indirect semiconductor holes and electrons have different momenta. Thus, to recombinate and fulfill momentum conservation law they need to do something with this uncompencated momentum. While in direct gap semiconductors hole+electron pair ...


3

Don't listen anyone. It is possible, but I have to admit - hard. Otherwise, how were first mono-crystals grown? Initially, you may buy 'pure' silicon (pure for chemical reactions, not electronics). First of all you need to make a rod. To do that you'll need form out of material which can withstand 1600C (hard part, can't name ones at the moment), and heat ...


3

Determine = design or measure? A dark-ish room, a white piece of paper and a ruler should do for a bright LED. Modelling it accurately, especially if the LED has a plastic lens built-in and you don't know the precise details of the die position, is trickier. If the LED has a builtin lens then about the best you can do is just match the angle coming out of ...


3

It's surprisingly difficult to find a nice simple description of how a transistor works. This description is from my old physics book - I suspect this may be oversimplified and I'm sure a complete description would run to lots of equations! Anyhow, this is what an NPN transistor looks like: so as you say, the collector-base junction is reverse biased and ...


3

An interesting question. You are right, the stress in a crystalline solid, or any solid, is treated by engineers as a macroscopic property of matter assuming matter is a continuous medium. It is given in terms of the external forces acting on the solid per unit area at some direction. Hence the distinction of $\sigma_{xy}, \sigma_{yz}$ etc. This goes with ...


3

In the atomic ground state a carbon atom has the electronic configuration $1s^22s^22p^2$. In the sp$^2$ hybridization the $2s$, $2p_x$, and $2p_y$ participate in the formation of the three $\sigma$ bonds and the $2p_z$ orbital forms a $\pi$ bond. According to molecular orbital theory this $2p_z$ state would form the bonding ($\pi$) and anti-bonding orbitals ...



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