Join now for JEE/NEET and also prepare for Boards Join now for JEE/NEET and also prepare for Boards. Register Now
Hey there! We receieved your request
Stay Tuned as we are going to contact you within 1 Hour
One of our academic counsellors will contact you within 1 working day.
Click to Chat
1800-1023-196
+91-120-4616500
CART 0
Use Coupon: CART20 and get 20% off on all online Study Material
Welcome User
OR
LOGIN
Complete Your Registration (Step 2 of 2 )
Sit and relax as our customer representative will contact you within 1 business day
why in n-type semiconductor only elements of group 15 are used as dopant? why in n-type semiconductor only elements of group 15 are used as dopant?
The answer delves into solid state physics.Basically in a large piece of material, the individual atomic orbitals mean nothing. You get larger, generalized states called the conducting band and valence bands. In the valence bands, electrons are confined to their respective atoms, but in energy states corresponding to the conduction band, they are free to move about.Between these two "levels" is an energy barrier called the bandgap. In metals, the bandgap is extremely small and the electrons readily move about in the material, allowing conduction. In semiconductors, the bandgap is of a medium size, so current can flow, but not too well. In insulators, the bandgap is so large as to make the conduction band inaccessible.When a dopant is added, you generally choose one that has either one more or one less electron than the parent material. Since the dopant is a tiny portion of the material, it is worked into the general band structure. However, the orbitals won't match up quite the same.In an n-type, it's highest energy electron will fall into the conduction band. Effectively, we've changed the conducting properties by adding conducting electrons to the system.In a p-type, we add something with one less electron than the main semiconductor. This introduces a "hole" in the valence layer. Electrons in the valence layer will jump from atom to atom to attempt to fill the hole, allowing conduction to occur in the valence layer.The purpose of transition metals as dopants is very different. It's often to take advantage of their catalytic properties or d-orbital electron configuration for colors.Thanks & RegardsRinkoo GuptaAskIITians Faculty
Dear , Preparing for entrance exams? Register yourself for the free demo class from askiitians.
points won -