3_1_3semicond_diode

6 10 19 coulombs mobile positive charge 16 10 19

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Ion The extra electron and the extra hole cancel out A LITTLE MATH n= number of free electrons p=number of holes ni=number of electrons in intrinsic silicon=10¹º/cm³ pi-number of holes in intrinsic silicon= 10¹º/cm³ Mobile negative charge = -1.6* 10-19 Coulombs Mobile positive charge = 1.6* 10-19 Coulombs At thermal equilibrium (no applied voltage) n* p=(ni)2 (room temperature approximation) The substrate is called n-type when it has more than 10¹º free electrons (similar for p-type) P-N Junction P-N s s s s Also known as a diode One of the basics of semiconductor technology Created by placing n-type and p-type material in close Created contact contact Diffusion - mobile charges (holes) in p-type combine with Diffusion mobile charges (electrons) in n-type mobile P-N Junction P-N s Region of charges left behind (dopants fixed in crystal Region lattice) lattice) – Group III in p-type (one less proton than Si- negative Group charge) charge) – Group IV in n-type (one more proton than Si - positive Group charge) charge) s Region is totally depleted of mobile charges - “depletion Region region” region” – Electric field forms due to fixed charges in the depletion Electric region region – Depletion region has high resistance due to lack of mobile Depletion charges charges THE P-N JUNCTION THE The Junction The The “ potent...
View Full Document

Ask a homework question - tutors are online