equilibrium

equilibrium - PN Diode - Equilibrium S. Tewksbury These...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

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

Unformatted text preview: PN Diode - Equilibrium S. Tewksbury These notes summarize the PN diode under equilibrium conditions (zero current either because the voltage across the diode is zero or because the contacts are not connected to anything. Apologies for the poor speech - not well rehearsed. EE471: PN Diode - Equilibrium Equilibrium No current flowing - Fermi level constant everywhere. P-type doping p = N A-> large n = (n i ) 2 /p -> small N-type doping n = N d-> large p = (n i ) 2 /n -> small P-type semiconductor with large density of holes, negligible electrons and N-type semiconductor with large density of electrons, negligible holes. Small electron density Mobile electron Mobile hole Fixed donor ion Fixed aceptor ion Small hole density Since fixed ions do not move, the figure below has eliminated their symbols so we can consider only the mobile charge. Mimicking the diode situation, we show the P-type (N-type) regions connected to regions with negligible hole(electron) densities. Holes will diffuse to the right from region of high hole density into region of low hole density. Electrons will diffuse to the left from region of high electron density into region of low ele tron density. Hole diffuses to right and recombines with electron, causing both to disappear. Exposed ionized impurities are left behind Both electrons and holes diffusing into other side. Region of ionized donors and acceptors appears Junction P-side depletion layer (depleted of holes) N-side depletion layer (depleted of electrons) Net negative charge Zero net charge Net positive charge Zero net charge Electron diffuses to left and recombines with hole, causing both to disappear Zero net charge Zero net charge...
View Full Document

Page1 / 8

equilibrium - PN Diode - Equilibrium S. Tewksbury These...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online