Gap Definition and 267 Threads

Even-though mathematicians regard themselves at the pinnacle or the http://forums.whirlpool.net.au/forum-replies.cfm?t=2330021&p=-1&# of all sciences they too are interested in partaking research areas in physics, e.g. topological quantum field theory, lie groups in quantum systems, ..., etc...

Hi all, I am extremely interested in GR, but somehow feel that the books I read are not really enough. Frankly, I find many question on this site and elsewhere completely bewildering, which makes me think that I don't have a solid foundation, especially in classical mechanics and various...

Could anyone please explain why doped semiconductors show decrease of the bang gap in comparison to the pure semiconductors. Web/literature links to relevant information will be appreciated. Thanks.

Is there any simple justification about graphene having no band gap? How bout its linear E-K? Why bilayer graphene has a quadratic E-K and electric field can open a band gap there? I do not completely understand the broken symmetry argument? Also Why MoS2 which has similar structure, do not...

In part branching off a discussion here, but also a discussion I've always been interested in having. I also want to take some time to answer the question in that thread: axo-axonic gap junctions in the hippocampus are thought to play a role in generating ultra-fast oscillations that have a...

Hello all, Does anyone knows what is the exact energy gap of Titanium Nitride (TiN) film? Is it indirect band gap or direct band gap? From literatures, I've found that the band gap for TiN is around 3.35-3.45eV. . May someone could suggest the specific band gap for TiN? Thanks.

According to solid state texts in Brillouin zone borders where diffraction condition satisfies we have a band gap. However I usually see Band gaps which are located in the center of Brillouin zone. Please correct me if I am wrong.

I am reading about the ionization energy in semiconductors and came across this thing that for Silicon, the ionization energy is lower than its band gap energy. I don't understand how can this be?

For which reason some of materials have direct gap and the other have indirect gap? In other words, what we have to do to convert a direct gap material to indirect one?

In my other thread on choosing a precalculus book for review, I went off topic and into calculus books, and how there seem to be these 3 main categories of books universities and high schools use -> the 1000+page ones with tons of examples, very computational, new editions every other year, etc...

I have a 30" diameter pipe that is supported about every 5-6 ft using bolts in a steel pipe support. As you can see in the attached photo, there is a pretty good size gap between the bolt/nut and the top surface of the pipe support, and also between the two faces of the interface. My question...

I have just completed my undergraduate degree, and will be taking the GRE and applying to graduate school this fall. I'll be applying to terminal master's programs because of my lackluster GPA, a 3.3. This is in hopes of continuing my recent track of improved grades, and hopefully...

I went back to school and so I have a gap between now and my last job. It's a 3 year gap. Should I do anything about it, like put school as one of my 'jobs' in the list to close up that gap? I fear that putting school at the top of the resume will call attention away from my jobs that I...

Looking for some feedback on this. I will have (by next month) completed a BS in physics and a BS in mechanical engineering. I applied to 5 nuclear engineering PhD programs, got into 2 but neither offered funding (tuition waiver + TA/RA). I've decided to work for 2 years. Over the next 2 years I...

My book says smaller the electrode gap,greater the chances of a misfire. The reason stated is that this is because of a smaller activated volume. I understand the meaning of misfire: it is when electricity takes a different path due to electrically conductive residue lying between electrode...

The superconduction gap equation is: 1=VN(0)arsinh(ωD/lΔl). My book says that in the weak coupling limit VN(0)<<1 this will reduce to: lΔl = ωDexp(-1/VN(0)) But how is this obtained. We have: arsinh(ωD/lΔl) = ln(ωD2+√(ωD2 + lΔl2)), but what has the approximation of this got to do...

Hi i have a question regarding the connection between Le chatelier and Waters self Ionization. I'd really appreciate if someone could give me heads up if my understanding is correct, or point me in the right direction if I'm off. Here we go: We know that water self-ionizes from the following...

Hello Friends How to calculate the minimum GAP distance between two electrodes?

Hello, I am currently in my senior year as an undergraduate and plan to apply to physics grad school in a year or two. I feel like taking some time off would help me become more focused and I don't have money to take the physics gre, or to apply for grad school. I also want to explore other...

I was wondering if diffraction of a wave can occur when the gap through which the wave passes is shorter than the wavelength itself. Then I came across this website http://www.talktalk.co.uk/reference/encyclopaedia/hutchinson/m0015966.html Which says that "In order for this effect to be...

of size n can consecutively occur in the sequence of primes.

Hello, For some reason, I need to leave the U.S. and go back to my country for two years once I finish my PhD. I am doing experimental condensed matter. In my country (an unkown place) , there is absolutely no way to do research in this field. I can only work as a lecturer in a university...

My book has a discussion of how the Bragg model can explain the origin of energy band gaps in solid. I have attached the relevant part of this discussion. I would very much like if someone could help me understand what it's basically trying to say. Facts: 1) In the free electron model, the...

Hey guys, i really need your help on this. I completed a 3 years BSc in physics in april 2013. However i am not at all satisfied with my preparation (the teachers at my college were hardly interested,yes that's the state of pure physics in my university!). I am planning to take a gap of a...

Hi, Which of ZnS and CdSe will have the larger band gap energy, explain. The answer is given as Zinc sulfide will have a larger band gap energy than cadmium selenide. Both are II-VI compounds, and Zn and S are both higher vertically in the periodic table than Cd and Se. In moving from...

Any ideas on how one can make a small gap (~10-50nm) between two parallel plates and maintain a known distance between them. I have two very flat surfaces and I would like to maintain a small gap (known gap) across them. I searched in the literature but I came up with nothing so if you have any...

I'm just starting back to school as for a BS in Physics and my plan is to follow that up with a PhD. While I can largely get my BS as a part time student over the next 4 years, when it come time to work on the PhD, I'll of course have to do school full time. I do have a plan in place where most...

Is it possible that, in the future, there would be very few people who know how to code, solder and debugging, while PDAs and internet access is available to everyone? I mean people know how to take a picture of themselves in a jacuzzi, apply tons of filter to make those pictures look neat, and...

Hi all, I would like to know if you guys could suggest me what's the best way to fill my free time (six months) between graduating high school and entering university. I will be taking Bachelor of Science with major in Physics. I also have plan to continue my study further if possible. However...

Can we measure the band energy gap from Fluorescence spectra? If yes, in what way? the excitation spectra or the emission spectra or both Is there a good reference on this subject specifically :smile:

Hey okay, so I have a 12V source which can provide a max of 10 mA, and I also have a switch that can go from open to close in 1 ms, How can I create an inductive circuit that will create a spark gap between electrodes that are 3mm apart? I did the math and found the breakdown voltage to be...

Hello, I'm a very curious EPE student (electrical power engineer) who is trying to figure out why there are variable gaps between joints of large steel structures. Because of this gap the stress seems to be distributed with peak force at the intersection of the bottom plate, why is this...

At what temp does nitrogen becomes plasma? What about oxygen? I am using a spark gap to turn air into plasma, I was wondering what temp is the air that the spark gap is flying through? Does the air in that area keep getting hotter and hotter the longer the spark gap is present?

What are the parameters affects the band gap in a band structure?

What's the purpose of having an air gap in certain gas lasers? Just to be clear, I'm talking about the air filled space between the lasing gas (with glass separating the two), and the partially silvered mirror at the end that let's the light out. Why isn't the partially silvered mirror just at...

Hal Haggard's ILQGS talk should be quite interesting. The plan is to have the slides PDF uploaded sometime Monday at http://bohr.physics.berkeley.edu/hal/pubs/Talks/ILQGS2013/haggard021213.pdf It's potentially helpful to let people look at the slides a day in advance of the Tuesday 12 February...

Is it possible that an electron of the 2s orbit fills the gap in 1s after electron capture? i believe no and it has something to do with the quantum-numbers but i can't find a conclusive explanation. or maybe i am totally wrong.

Homework Statement Hi, I'm trying to show how the band gap energy changes with the radius as Part 2 of this questions asks us to find: http://screencast.com/t/N7R42aS4l The full solution is here: http://screencast.com/t/y1K3hqOus4H Homework Equations See solution link above. The Attempt...

Why is it that the air gap flux density is flat topped at no load. What happens to it's shape when machine is loaded?

I've been looking on journals and textbook, as well as internet. Does anybody know if there is an equation to find out the value of direct optical band gap and indirect optical band gap? What is the difference of optical band gap, direct optical bandgap and indirect optical bandgap? also...

Homework Statement A shallowly curved piece of glass is placed on a flat one. When viewed from above, concentric circles appear that are called Newton’s rings. In order to see bright rings, the gap can be: 1. 0 2. 1/4λ 3. 1/2λ 4. λ Homework Equations 1/2 λ occurs when n2>n1...

This was out of a physics book, but since it's just geometry, I thought this would be the best forum to ask about it. I was reading through a derivation of the far electric field of a uniformly polarized sphere, and the author used a trick where he modeled the sphere as two displaced spheres...

hello, is there anyone who can help me in the band gap calculation. my situation is that: I can calculate the band gap of sigle crystalline graphene, because i know the high symmetrical pionts of the first Brillouin zone of an hexagonal crystalline(M-G-K-M). But the problem is that...

Hi, I'm going into my junior year and I was thinking of taking a gap year to do something entirely different than Physics. Do grad schools look down on people who took a gap year during the progress of their degree? Will they require you to explain what happened during that year? Thanks! :smile:

Gap exponents are denoted like critical exponents for higher derivatives of Gibbs potential. \Delta_l' (\frac{\partial G}{\partial H})_T=G^{(1)}\propto (1-\frac{T}{T_c})^{-\Delta_1'}G^{0} (\frac{\partial^l G}{\partial H^l})_T=G^{(1)}\propto (1-\frac{T}{T_c})^{-\Delta_l'}G^{l-1} \alpha'...

What are the consequences of a possible solution to Yang-Mills existence and mass gap problem? Are the consequences only physical or they will also have applications to other branches of science or life? If yes, what are they?

In a metallic system, the Fermi level is crossed either from the conducting zone into the non-conducting zone or vice versa. Is there an interpretation one can give to the direction of the crossing? In other words, if the 1D band gap diagram shows the fermi line is crossed from the...

Hi, I've completed one year of undergrad. I started in engineering but have now decided that I want to pursue math. Before continuing, I want to take a year off to refocus and take care of other aspects of my life. I feel like I will do better if I take a year off. On the other hand, I enjoy...

I am new to solid state physics, having been in computational chemistry (quantum mechanics) for the larger part of my career. Hence have a lot of newbie like questions that are not easily answered by google/wikipedia searching. 1)In viewing a 1-dimensional band gap diagram, crossing the...

Hello everyone, I am one of those non-majors trying to get into graduate school (eventually). Long story short, I have a year left as a business major, during which time I will be taking Calculus 2 and the introductory physics w/lab sequence. I have recently met with both the graduate...