Minority Carrier Diffusion Currents

Electron Diffusion Current

j_n = -e * D_n * (dn/dx)

Where:

• j_n: Electron diffusion current density
• D_n: Electron diffusion coefficient
• dn/dx: Electron density gradient

Generation-Recombination Current Analysis

Net Generation Rate

When hole density at boundary is lowered below equilibrium (p < p10):

U = -(p10 - p) / tau_p

Thermal Generation Rate

g_th = p10 / tau_p

Recombination Rate

r = p / tau_p

Decision Logic

1. Calculate diffusion currents from density gradients using Eq. 28.1 and 28.2
2. Determine net generation/recombination:
   • IF p < p10: Net generation (U < 0)
   • IF p > p10: Net recombination (U > 0)
   • IF p = p10: Equilibrium (U = 0)
3. Account for concurrent changes in majority carrier current due to GR processes

Important Notes

• Minority currents are often negligible compared to majority currents in homogeneous bulk unless gradients are large
• Diffusion currents are related to concurrent changes in electron current through generation/recombination
• Minority carrier lifetime (tau_p) is a critical parameter for GR current calculations3b:["$","$L44",null,{"content":"$45","frontMatter":{"name":"minority-carrier-diffusion-currents","description":"Calculate minority carrier diffusion and generation-recombination (GR) currents in PN junctions, bulk semiconductors, and diodes. Use when analyzing minority carrier transport, calculating diffusion currents from density gradients, or determining thermal GR-currents at boundaries where carrier density deviates from equilibrium."}}]