why it is compulsary to provide an overlap between the source and drain with gate...?

[surya92]

why it is compulsory to provide an overlap between the source and drain with gate...?

 

[rahdirs]

• The overlap between the gate and the source and drain region is required to ensure that the inversion layer forms a continuous conducting path between the source and drain region. Typically this overlap is made as small as possible in order to minimize its parasitic capacitance.
• Gate-to-Source/ Drain overlap assures good electrostatic control of the channel, and hence, a strong ON state current ION.