Lecture9-PhotoThermalRecombGenerMinorityLifetimes

Lecture9-PhotoThermalRecombGenerMinorityLifetimes - ECE...

Info iconThis preview shows pages 1–7. 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

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: ECE 3040 - Dr. Alan Doolittle Georgia Tech Lecture 9 Photogeneration, Absorption, and Nonequilibrium Reading: Pierret 3.3-3.4 ECE 3040 - Dr. Alan Doolittle Georgia Tech Photogeneration Light with photon energy, h < Eg is not easily absorbed. A convenient expression for the energy of light is E=1.24/ where is the wavelength of the light in um. Light with energy, h > Eg is absorbed with the unabsorbed light intensity as a function of depth into the semiconductor is I(x) = I o e- x where Io is the initial light intensity, x is distance and is the absorption coefficient [1/cm]. h < Eg h > Eg ECE 3040 - Dr. Alan Doolittle Georgia Tech Photogeneration ECE 3040 - Dr. Alan Doolittle Georgia Tech Photogeneration Each Photon with energy greater than Eg can result in one electron hole pair. Thus, we can say, ( ) Sec cm e G x G where x G t p t n x LO L L Light Light = = = 3 # ) , ( ) , ( If is small (near bandgap light), the generation profile can be approximately constant. If is large (light with energy>> bandgap), the generation profile can be approximated as at the surface. ECE 3040 - Dr. Alan Doolittle Georgia Tech Important Nomenclature n= n+n o and p= p+p o In Non-equilibrium, np does not equal n i 2 Low Level Injection p= n <<n o and n~n o in n-type material p= n <<p o and p~p o in p-type material ECE 3040 - Dr. Alan Doolittle Georgia Tech p can be >> p o If p>>p o , p~ p Carrier Concentrations after a Perturbation Steady State if perturbation has been applied for a long time Non-Steady State, Nonequilibrium Equilibrium p(t=0)>p o or p(t=0)<p o p(t=0)> p(t)> p...
View Full Document

This note was uploaded on 08/23/2011 for the course ECE 3040 taught by Professor Doolittle during the Spring '11 term at University of Florida.

Page1 / 16

Lecture9-PhotoThermalRecombGenerMinorityLifetimes - ECE...

This preview shows document pages 1 - 7. Sign up to view the full document.

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