Enhancement Mode of D-MOSFET

This figure shows the enhancement mode of operation of N-channel D-MOSFET.Whole construction is similar to the depletion mode of operation of D-MOSFET.But in this enhancement mode of operation of D-MOSFET ,it has no conducting channel .The whole construction acts as capacitor .In this N-channel D-MOSFET ,gate terminal is in positive potential ,it produce negative charges in the N-type conducting channel as shown in above figure .The free electrons drawn in to the N-type conducting channel. by these negative charges.In enhancement mode of operation of the D-MOSFET,free electrons are added in the conducting channel. .As the result amount of the the free electrons are increased in the conducting channel .So N-type conducting channel is enhances or increase .When positive potential on the gate terminal is enhances ( i.e increase) and the amount of the free electrons in the conducting channel is enhanced .From the above discussion we can noted that the amount of the current conduction from the source terminal to the drain terminal through the N-type conducting channel is controlled by the amount of the positive potential on the gate terminal .

When positive potential on the gate terminal is enhances the conductivity of the channel is also enhance .This is the main differences of the D-MOSFET to the JFET .JFET can not be worked in the enhancement mode operation on the opsitive gate termianl.So we can noted that the positive potential on the gate terminal operation is called the enhancement mode of operation of the D-MOSFET.

Depletion Mode of D-MOSFET

This figure shows the N-channel depletion mode of operation of D-MOSFET.Where the gate terminal is negative potential ,electrons are gather on the gate terminal and protons are gather on the N-type conducting channel (i.e electrons is empty on the N-type conducting channel or depleted) but there are some little free electrons which are responsible for current conduction via N-type conducting channel of D-MOSFET.According to the values of the negative potential on the gate terminal,the resistance of the N-type conducting channel of the D-MOSFET is increase. Consequently ,lesser amount of the free electrons are responsible for the lesser amount current from source terminal to the drain terminal through the N-type conducting channel.From the above discussion, we know that the amount of the current flow from the source terminal to the drain terminal through the N-type conducting channel of the D-MOSFET is controlled by the changing the negative potential on the gate terminal .So the operation is depends on the depleting the N-type conducting channel of free electrons .The negative potential on the gate terminal ,the operation is known as depletion mode of operation of the D-MOSFET.

Operation Mode of D-MOSFET

We know that D-MOSFET can be worked in two mode of operation ,one is depletion mode of operation and another is enhancement mode of operation.Form the construction details of the D-MOSFET we can noted that the whole construction of the D-MOSFET behaves as capacitor where gate terminal of the D-MOSFET acts as one plate of this capacitor and the N-type of conducting channel is acts as another plate of this capacitor .The layer of the metallic oxide (generally the silicon dioxide ) of acts as the dielectric of the capacitor.On the basis of the gate terminal potential the D-MOSFET working mode is classified in two working mode of operation i.e negative potential of the gate terminal operation of the D-MOSFET is called depletion mode of operation and the positive potential of the gate terminal operation of the D-MOSFET is called the enhancement mode of operation.