PN Junction Diode Forward Bias

Forward-Biased PN Junction

• When a forward-bias voltage is applied, the potential barrier is lowered, allowing holes from the p region and electrons from the n region to flow across the junction.
• Boundary conditions are derived for minority carrier hole concentration in the n region at the space charge edge and minority carrier electron concentration in the p region at the space charge edge.
• Injected holes in the n region and electrons in the p region become excess minority carriers.

Excess Minority Carrier Behavior

• The behavior of excess minority carriers is described by the ambipolar transport equation developed in Chapter 6.
• Solving the ambipolar transport equation and using the boundary conditions, steady-state minority carrier hole and electron concentrations in the n region and p region are derived.

Minority Carrier Diffusion Currents

• Gradients exist in minority carrier hole and electron concentrations, resulting in minority carrier diffusion currents in the pn junction.
• These diffusion currents yield the ideal current-voltage relationship of the pn junction diode.

Reverse-Biased PN Junction

• Excess carriers are generated in the space charge region of a reverse-biased pn junction.
• These carriers are swept out by the electric field, creating the reverse-biased generation current, another component of the reverse-biased diode current.

Learn about the behavior of a PN junction diode when a forward-bias voltage is applied. Understand how the potential barrier is affected and how minority carriers flow across the junction. Test your knowledge on the boundary conditions and electron flow in this quiz.