A p-n junction at thermal equilibrium has the space-charge density ρ(x) shown. Which graph best represents the electric field E(x) across the depletion layer of width W? Image
Options

Question

A p-n junction at thermal equilibrium has the space-charge density ρ(x) shown. Which graph best represents the electric field E(x) across the depletion layer of width W? Image

G1 Physics · Accepted Answer

Poisson's relation gives dE/dx = ρ/ε. Integrating the shown piecewise-linear ρ(x) gives a continuous parabolic electric-field curve that is zero at the depletion edges and extremal at the junction. The matching source graph is option B.