Final answer:
The threshold voltage in a MOS system is the minimum voltage required to create an inversion layer of charge carriers in the semiconductor channel, allowing current to flow. When the gate voltage is below the threshold voltage, the channel acts as an insulator. When the gate voltage exceeds the threshold voltage, the channel becomes conductive.
Step-by-step explanation:
In a MOS (Metal-Oxide-Semiconductor) system, the threshold voltage is the minimum voltage that needs to be applied to the gate terminal in order to create an inversion layer of charge carriers in the semiconductor channel, allowing current to flow between the source and drain terminals.
When the applied gate voltage is below the threshold voltage, the semiconductor channel remains in its original state and acts as an insulator, preventing the flow of current. However, when the gate voltage exceeds the threshold voltage, the channel becomes conductive and current can flow through it.
For example, let's consider an n-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). When the gate voltage is below the threshold voltage, the channel is depleted and no current flows. However, when the gate voltage is higher than the threshold voltage, the channel is inverted and current can flow from the source terminal to the drain terminal.