Heterojunction Band Diagrams Explained

/ edmundsj
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How to draw band diagrams for heterojunctions (when two different semiconductors meet). Heterojunctions are critical in virtually all modern optical electronics, as well as in the study of quantum mechanics, and in this video I describe how to draw their band diagrams.
This is part of my series on semiconductor physics (often called Electronics 1 at university). This is based on the book Semiconductor Physics and Devices by Donald Neamen, as well as the EECS 170A/174 courses taught at UC Irvine.
Hope you found this video helpful, please post in the comments below anything I can do to improve future videos, or suggestions you have for future videos.

[@mennaelmanzalawy2275]

This is great, thank you.

[@balrampillai5314]

Thanks, very clear explanation!

[@missiman8983]

Thank you for this useful video

[@anudogra4810]

very nicely explain, thanks for your help

[@dinanamer6490]

Thanks for your explanation

[@ahmedalanazi9682]

Well! This is a good explanation, What if we use a metals like Ag or Au does these change the bending between two semiconductors. does this facilitated the charge transfer Hole-Electron between valence band and conduction band in our semiconductors Thank you for the video

[@a.i9331]

very useful, thank you

[@AB-uh7ub]

A truly life saver,,, thank you sir

[@mohammadrahmani2304]

nailed man , keeps going!!!

[@frommarkham424]

Your videos are nice

[@evelyndeagueros8825]

how do you know when the bands should bend upwards or downwards? or if the band should connect to the top of discontinuity? why does the band diagram for a n-n/p-p heterojunction look the way it does??

[@lirabin]

Exactly my question. watched many videos but no one explain this. why does the jump in 11:05 is on the start of the falling and not in the end of it..?

[@asifhossain2863]

nice to start hetero junction!

[@rameejatabdulrasheed4127]

Thank you, very much

[@user-yc2er6iu8f]

I'm wondering where are the ' next videos'. Really want to see a full series. Should I subscribe to something then I could watch the whole videos? Plz inform, and I'm willing to pay for it.

[@dominickoyroytsaltis-mcqui3644]

What happens when you apply a forward bias to one of the sides?

[@JordanEdmundsEECS]

Great question! I will make a video on this sometime. The short answer is that just as with the P/N junction, you will start to bend the bands (or undo the bending of a doped structure). The weird part is that this won't cause as much current to flow because of the quantum well. You can solve for the band structure by treating the quantum well as a capacitor/dielectric (just like as in a MOSFET), but you will actually get some current due to carrier leakage out of the quantum well. How much depends on the height of the quantum well.

[@nidhiyaduvanshi2815]

Nice explanation about band bending on p and n side. But in case, if we have one intrinsic semiconductor and other is lightly n doped? Then how to find a band bending amount on both sides??

[@seonoak7910]

THX!

[@ernestschu8932]

hi, I thinks in the case of pn junction, with the alignment of fermi level, the vacuum levels should also bend instead of still keeping in a same level.

[@rajgavadiya2814]

you are right bro

[@vijaylaxmigupta6787]

Please share the video of semiconductors and metal interaction band diagrams

[@hasan8381]

Can you explain the band bending in the broken band (type III) ??

[@1q1q1q1q1q1q1qw]

why can i assume a common vaccum level. because in every semiconductor i need a diffrent amount of energy to remove an elektron or?

[@JordanEdmundsEECS]

Great question! If the vacuum level weren't constant, that would mean you could change a particle's energy by just moving it around near the surface of a material to a location with a different vacuum level. It would violate conservation of energy.

[@mohitmaurya8741]

I watched your full video because of the thumbnail but you are not explaining that thing which one you telling in thumbnail

[@perjoergensen3423]

Why is it imporant that the two semiconductors, that is brought into contact, have similar work-functions? (If it is important). Obviously it's important for a metal-semiconductor junction in regards to the obtaining a low barrier (Schottky barrier) to allow electron transport, but why is it important for a semiconductor-semiconductor?

[@JordanEdmundsEECS]

It’s not important, it just makes things a lot easier to explain at first. The difference in Fermi levels just leads to band bending, but the interesting discontinuities all show up even when the difference is zero.

[@icant_thinkbetter]

Thank you

[@JordanEdmundsEECS]

You are most welcome.

[@mangapathiraju7198]

Great...

[@waqasmughal7708]

in case of valence band why you consider the electron affinity in the equation while it is a simply a difference between Eg1-Eg2

[@asifbhat3408]

Hii, Can you please do a video on heterojunction e.g., AlGaN/GaN HEMT band diagrams with explanations please. Anyways thanks for doing what you do....appreciated

[@ZhansDoIT]

[@misterhtechnologies3293]

Please provide a One page summary with Diagrams. I need to Submit my Physics assignment

[@allansh828]

1st

[@JordanEdmundsEECS]

xD

[@ruchinishad2254]

Sir hindi me smjha sakte ho kya aap