ECE Purdue Semiconductor Fundamentals L1.6: Materials Properties - Doping

This video is part of the course "Semiconductor Fundamentals" taught by Mark Lundstrom at Purdue University. The course can be found on nanoHUB.org at nanohub.org/courses/sfun or on edX at www.edx.org/course/semiconduc... .
This course provides the essential foundations required to understand the operation of semiconductor devices such as transistors, diodes, solar cells, light-emitting devices, and more. The material will primarily appeal to electrical engineering students whose interests are in applications of semiconductor devices in circuits and systems. The treatment is physical and intuitive, and not heavily mathematical.
Technology users will gain an understanding of the semiconductor physics that is the basis for devices. Semiconductor technology developers may find it a useful starting point for diving deeper into condensed matter physics, statistical mechanics, thermodynamics, and materials science. The course presents an electrical engineering perspective on semiconductors, but those in other fields may find it a useful introduction to the approach that has guided the development of semiconductor technology for the past 50+ years.

[@blacklightning7227]

I love that you continue to reiterate and reincorporate the information until the vocabulary becomes synthesized, so that I can continue to build upon the story in my mind; thank you for your dedication to education on this material that requires focus to understand correctly.

[@blacklightning7227]

Awesome course. Thanks.

[@BlackRockExecutive]

It was mentioned that at room temperatures, intrinsic carrier concentration pales in comparison to the extrinsic carriers, which would mean that n/N_D

[@seinfan9]

"n" is not just intrinsic carrier concentration, it is concentration of electrons in the conduction band, which includes both intrinsic and extrinsic (from the ionized donors) carriers. At room temperature, total carrier concentration is approximately equal to the dopant concentration "N_d", which results in the equals 1 ratio.
So to restate what is going on:
At 0K, there are absolutely no donors in the conduction band, and there are absolutely no electron-hole pairs that have been created from the intrinsic material. Carrier concentration is absolutely zero.
At low temperatures below 300K, some of the dopant material becomes ionized and electrons from those ionized donors are now present in the conduction band (because of the extremely small energy bandgap between the dopant material and the intrinsic material). There are effectively zero intrinsic carriers in the conduction band at this point still. Carrier concentration is slightly above zero.
At room temperature 300K, the dopant material is effectively entirely ionized and almost all electrons from the ionized donors are now in the conduction band. Some intrinsic carriers are now present in the conduction band, but it is multiple orders of magnitude less than the extrinsic carriers. Carrier concentration is effectively the amount of ionized donors, hence the "extrinsic" region.
At high temperatures, the dopant material is completely ionized, but now there are much more electron-hole pairs that have been created within the intrinsic material and this amount dominates the ionized donors. Carrier concentration is effectively the intrinsic concentration, hence the "intrinsic" region.

[@BlackRockExecutive]

@@seinfan9 Thanks for the clarification! I wasn't notified on yr reply until I rewatched the video. I've always mistakenly thought the graph was n_i/N_D. My bad, thanks again!

[@drscott1]

👍🏼

[@user-il6ke6dl3q]