Distinguish between reverse and forward biasing of a diode, and illustrate with circuit diagrams and band energy diagrams.

Here are the circuit diagrams and the description of the band energy diagram: 4(a) (i) Distinction between Reverse and Forward Biasing of a Diode Forward Bias: In forward bias, the positive terminal of the voltage source is connected to the anode (P-side) of the diode, and the negative terminal is connected to the cathode (N-side). This reduces the width of the depletion region, allowing current to flow easily through the diode. Voltage Source (+) Anode (P-side) Diode (| ) Cathode (N-side) Voltage Source (-) A more detailed representation: ` + V_source - | | R | | | |>| | (Diode symbol: triangle points to N-side, bar is N-side) | | ------------ ` In this configuration, the diode conducts current. Reverse Bias: In reverse bias, the positive terminal of the voltage source is connected to the cathode (N-side) of the diode, and the negative terminal is connected to the anode (P-side). This increases the width of the depletion region, significantly reducing current flow (ideally, no current flows, but a small leakage current exists). Voltage Source (-) Anode (P-side) Diode (| ) Cathode (N-side) Voltage Source (+) A more detailed representation: ` V_source + | | R | | | |>| | (Diode symbol: triangle points to N-side, bar is N-side) | | ------------ ` In this configuration, the diode blocks current. 4(a) (ii) Band Energy Diagram of a Typical Diode (at Equilibrium) A typical band energy diagram for an unbiased P-N junction shows the energy levels across the junction: • On the P-side, the valence band (E_V) is close to the Fermi level (E_F), indicating a high concentration of holes. The conduction band (E_C) is higher in energy. • On the N-side, the conduction band (E_C) is close to the Fermi level (E_F), indicating a high concentration of electrons. The valence band (E_V) is lower in energy. • Across the depletion region (the junction), the energy bands bend. The conduction band (E_C) and valence band (E_V) are higher in energy on the P-side and lower on the N-side. • The Fermi level (E_F) remains constant across the entire P-N junction at equilibrium, indicating no net flow of charge carriers. • The difference in energy between the conduction band on the P-side and the conduction band on the N-side (or similarly for the valence band) represents the built-in potential barrier (V_0). Last free one today — make it count tomorrow, or type /upgrade for unlimited.