The correct answer is: D. n-type substrate of high doping level.
An nMOSFET (n-channel metal-oxide-semiconductor field-effect transistor) is a type of transistor that uses an n-type semiconductor material as its channel. The channel is a thin layer of semiconductor material that is sandwiched between two insulating layers, called the gate oxide and the substrate. The gate oxide is a thin layer of silicon dioxide that separates the channel from the gate electrode. The substrate is the underlying semiconductor material that the channel is formed on.
The nMOSFET is a type of field-effect transistor (FET), which means that it is controlled by an electric field. The electric field is created by applying a voltage to the gate electrode. When a voltage is applied to the gate electrode, it creates an electric field that attracts electrons to the channel. This causes the channel to become conductive, allowing current to flow through the transistor.
The nMOSFET is a very versatile device that can be used in a variety of applications, including digital circuits, analog circuits, and power electronics. It is one of the most widely used types of transistors in the world.
Here is a brief explanation of each option:
- Option A: p-type substrate of high doping level. This is not the correct answer because nMOSFETs are formed in n-type substrates.
- Option B: n-type substrate of low doping level. This is not the correct answer because nMOSFETs are formed in n-type substrates with a high doping level.
- Option C: p-type substrate of moderate doping level. This is not the correct answer because nMOSFETs are formed in n-type substrates.
- Option D: n-type substrate of high doping level. This is the correct answer because nMOSFETs are formed in n-type substrates with a high doping level.