What is a double-base diode, the structure, working principle, operation modes, characteristics, and application fields of a double-base diode 1

The bipolar junction transistor (BJT), commonly known as a BJT, is a widely used electronic device in circuits such as amplification, switching, and voltage regulation. It consists of three semiconductor materials with different doping types: P-type, N-type, and P-type, forming two PN junctions. Depending on the doping types, BJTs can be categorized as NPN or PNP.diode

1. Structure

The structure of a bipolar junction transistor (BJT) consists of three regions: the emitter, the base, and the collector. In an NPN-type BJT, the emitter and base are N-type semiconductors, while the collector is a P-type semiconductor. In a PNP-type BJT, the emitter and base are P-type semiconductors, and the collector is an N-type semiconductor. The junction between the emitter and collector is called the emitter junction, while the junction between the base and collector is called the collector junction.diode

II. Working Principle

The working principle of BJT is based on two fundamental physical effects: the drift and diffusion of holes in P-type material and electrons in N-type material under an electric field. Under forward bias, the emitter junction is forward-biased, enabling electron injection into the emitter region, while the base junction is reverse-biased, restricting electron injection into the base region. When electrons injected from the emitter region recombine with holes injected from the base region, a current amplification effect is generated.diode