2. Consider the pl-p2 "isotype" step junction shown in Figure 1. a) Draw the equilibrium energy band diagram for the junction, taking the doping to be non degenerate and NA1 > NA2 b) Derive an expression for the built-in voltage (Vbi) that exists across the junction under equilibrium conditions c) Make rough sketches of the potential, electric field, and charge density inside the junction. d) Briefly describe the depletion approximation NA2 NAI Figure 1