Blue line (Ec): Conduction band edge - electrons above this energy are mobile
Red line (Ev): Valence band edge - holes below this energy are mobile
Purple dashed (Ei): Intrinsic Fermi level - where Fermi level would be without doping
Green line (EF): Equilibrium Fermi level - constant throughout device at equilibrium
Cyan/Orange dashed: Quasi-Fermi levels for electrons (EFn) and holes (EFp) under bias/illumination
Band bending: Shows the built-in electric field in the depletion region
φ(x) (Potential plot): Electrostatic potential across the junction showing φbi (built-in potential). x-axis runs from −xp to xn with 0 at the metallurgical junction
E(x) (Electric field plot): Electric field in the depletion region, peaking at the junction. Triangular profile from the depletion approximation