What happens in an n-channel MOSFET when no voltage is applied to its gate?

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NMOS transistorNegative-channel metal-oxide semiconductors (NMOS) employ a positive secondary voltage to switch a shallow layer of p-type semiconductor material below the gate into n-type. For positive-channel metal-oxide semiconductors (PMOS), all these polarities are reversed. NMOS transistors are more expensive, but faster, than PMOS transistors. — transistor NMOS transistor
Negative-channel metal-oxide semiconductors (NMOS) employ a positive secondary voltage to switch a shallow layer of p-type semiconductor material below the gate into n-type. For positive-channel metal-oxide semiconductors (PMOS), all these polarities are reversed. NMOS transistors are more expensive, but faster, than PMOS transistors.

In an n-channel enhancement-mode MOSFET, the device is normally switched off when no voltage is applied to the gate.12

Structurally, the source and drain regions are separated by a substrate of opposite polarity, creating two p-n junctions connected back-to-back. Because of this configuration, no conductive path exists between the source and the drain in the absence of a gate voltage. Consequently, the only current that can flow between these terminals is a negligible leakage current. The transistor only becomes conductive when a sufficient positive voltage is applied to the gate, which attracts electrons to the surface to form an n-type channel, thereby bridging the gap between the source and the drain.12