Band Theory & Doping: Conduction in semiconductors depends on band gap energy $E_g$. N-type doping adds donor electrons near conduction band; P-type doping creates acceptor holes near valence band.
PN Junction Diode (Shockley Equation): Current through a diode under bias voltage $V$ is $I = I_s \left( e^{qV / (n k_B T)} - 1 \right)$. Forward bias overcomes built-in potential barrier; reverse bias induces saturation current $I_s$.
Bipolar Junction Transistors (BJT): Transistor current relations: $I_E = I_B + I_C$ with current gain $\beta = I_C / I_B$. Operates in Cutoff, Active (linear amplification), and Saturation regimes.
Operating Instructions: Switch tabs in the left sidebar to explore Semiconductor energy bands, Diode IV characteristics, and Transistor switching/gain.