Question #43749

A reverse-biased silicon p-n junction is uniformly illuminated by monochromatic light of wavelength $\lambda = 620 \text{ nm}$ and intensity $I = 3.2 \text{ W/m}^2$. The incident photon flux $\Phi_0$ generates electron-hole pairs at a uniform volume rate $G = \alpha \Phi_0$ throughout the device, where $\alpha = 4 \times 10^3 \text{ m}^{-1}$ is the absorption coefficient. The depletion region of the junction has a width $W = 2.0 \text{ \mu m}$. The minority carrier diffusion lengths in the p-type and n-type neutral regions are $L_n = 8.0 \text{ \mu m}$ and $L_p = 15.0 \text{ \mu m}$, respectively. Assuming steady-state conditions and that all minority carriers generated within one diffusion length of the depletion region reach the junction to contribute to the current, what is the magnitude of the total steady-state photocurrent density $J_{ph}$?

(Take the energy of a photon as $E = \frac{hc}{\lambda}$, $hc = 1240 \text{ eV}\cdot\text{nm}$, and elementary charge $e = 1.6 \times 10^{-19} \text{ C}$)