Transcript Chapter 3, Current in Homogeneous Semiconductors

Chapter 3, Current in
Homogeneous Semiconductors
• Carrier Motion
• Current Flow
– Drift
– Diffusion
• Recombination/Generation
• Continuity Equations
• Use of Continuity Equations
•Optical Phonons
•Ionization
•Intra-valley scattering
•Inter-valley scattering
•Notation Reminder
•no, po: equilibrium
•n, p: general carrier
concentrations
Reference: Pierret, Section 5.2
Electrons removed.
Holes removed.
3
Electrons added to condution band.
Holes added to valence band.
(Definitions)
From nT/NT
no
Note: R corresponds to generation here!!
Reference: Pierret, Section 5.3.
(Fn – flux of electrons)
Equilibrium
Excess carriers
Gop is from light shining on the
semiconductor
Normal recombination.
Depend on details of situation.
For normal, low-level injection, p<<ND
Minority carrier
diffusion length
for holes.
For direct bandgap semiconductors, R=βnp for direct band to band recombination.