= Depletion-region generation current
{title2=$I_{\rm gen}\sim e\mathcal A Wn_i/(2\tau_g)$}
Thermal generation of <electron-hole pairs> within a reverse-biased <depletion region> can supply a leakage <electric current> in addition to neutral-region diffusion. For a simple midgap trap with equal electron and hole lifetime parameters, its scale is $e\mathcal A Wn_i/(2\tau_g)$, where $W$ is depletion width and $\tau_g$ the lifetime parameter. The <electric field> separates generated carriers. Unlike ideal <diode minority-carrier diffusion current>, this contribution scales approximately with $n_i$ rather than $n_i^2$ and can vary with reverse voltage through $W$. Consequently a measured activation energy need not equal the full <band gap>.
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