τ e , τ h electron & hole minority carrier lifetimes respectively L e , L h electron & hole minority carrier diffusion lengths respectively µ e , µ h electron & hole mobilities respectively (cm 2 /V-sec) D e , D h electron & hole diffusivities respectively (cm 2 /sec) n e , n h the electron & hole concentrations respectively n e0 , n h0 electron & hole concentrations in thermal equilibrium n i ...