Solar Cell Device Physics, 2nd Edition

APPENDIX G

Determining n(x) for the Space-charge-neutral Region of a Heterojunction p-type Bottom Material

We consider here a space-charge-neutral region (W₁ + W₂) ≤ x ≤ (W₁ + W₂ + L) in the bottom layer of the heterojunction seen in Figure 5.40. To have such a layer, we have assumed that material 2 is a lifetime semiconductor (see Appendix E). We also now assume that electrons remain the minority carrier under illumination and that we can use a linear lifetime model for recombination. Under these conditions, the governing equation for n(x) is:

(G.1)

Our goal here is to find the solution to Eq. G.1 subject to the boundary conditions

(G.2)