How mosfet works

The working principle of MOSFET: The gate bias applies an electric field to produce a field effect in the substrate. The field effect forms an inversion layer connecting the source and drain. The inversion layer forms a path, and current flows from the source to the drain to achieve conduction. When the gate bias is removed, the inversion layer disappears and the current flow is blocked, achieving cutoff.

The working principle of MOSFET

Metal oxide semiconductor field effect transistor (MOSFET) is a widely used Semiconductor devices in electronic products. Its working principle is based on field effect.

Field Effect

When an electric field is applied to a semiconductor, it affects the behavior of carriers in the semiconductor. For example, a positive electric field repels electrons (negative charge carriers) to one side of the semiconductor, leaving more holes (positive charge carriers). This effect is called field effect.

MOSFET Structure

MOSFET consists of a silicon substrate, source, drain and gate.

• Silicon substrate: The semiconductor material (usually N-type or P-type) that forms the basis of MOSFETs.
• Source and Drain: Metal contacts used to provide current to the MOSFET.
• Gate: The metal contact between the conductor (usually metal) and the insulating layer (oxide), used to control the on and off of the MOSFET.

Principle of Operation

The operating principle of MOSFET involves the following steps:

1. Gate Biasing: When a positive voltage is applied to the gate, it creates an electric field between the substrate and the insulating layer.
2. Field effect: The electric field attracts holes or electrons (depending on the type of substrate) in the substrate, forming a region called the inversion layer.
3. Inversion layer: The inversion layer is a region with higher conductivity that connects the source and drain.
4. Conduction: When the inversion layer is formed, current can flow from source to drain. MOSFET turns on.
5. Cutoff: When the gate bias is removed, the inversion layer disappears and current flow can no longer flow to the drain. MOSFET is off.

By controlling the gate voltage, the MOSFET can be turned on or off, thereby controlling the flow of current.

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