Question

Which of the following statements about the MOS transistor is INCORRECT ?
1. The heart of a MOS transistor is the MOS capacitor
2. In modern MOS transistors, the metal layer is often replaced by highly doped Si₃N₄
3. The oxide thickness, which is typically of the order of 0.01 μm is crucial in determining the behaviour of the MOS capacitor.
4. It derives its name from materials involved in the early transistor of metal, oxide, and semiconductor.

Answer 1

Correct Answer - Option 2 : In modern MOS transistors, the metal layer is often replaced by highly doped Si₃N₄

The MOS transistor (or MOSFET, i.e., MOS field-effect transistor) derives its name from the materials involved in the early transistors of this type: metal, oxide (SiO₂), and semiconductor.

In modern MOS transistors, the metal layer is often replaced by highly doped polycrystalline silicon, and the oxide layer by a combination of SiO₂ and Si₃N₄ or by other insulators.

The semiconductor is invariably silicon because it is relatively difficult to grow or deposit a high-quality insulating layer on other semiconductors.