MOSFET
For a typical MOSFET in an integrated circuit, which statement about the source and drain is correct?
- AThe structure is nearly symmetric, and which side acts as the source depends on the potentials
- BThe source always has a higher impurity concentration than the drain
- CThe source and drain are made of different semiconductor materials
Show answer and explanation
Answer: A. The structure is nearly symmetric, and which side acts as the source depends on the potentials
In a typical integrated-circuit MOSFET, the source and drain are diffusion regions with the same structure and are nearly symmetric. In an nMOS device, the side at lower potential acts as the source and the higher side as the drain. The current direction can even reverse, as in a transmission gate.
- A. Correct. The structure is symmetric, and the potentials decide the roles.
- B. In an ordinary MOSFET, the source and drain have the same doping.
- C. The source and drain are made of the same material in the same process step.