Tunnel field effect transistor (TFET) is replacing other similar devices, because of it's extremely lower value of sub-threshold swing (SS) and leakage current. Due to the limitations of ambipolar effect and relatively lower value of ON-current, researches are trying to enhance the performance of it by modification in the structure and choice of appropriate materials. To increase the ON-current, a highly dense thin layer source pocket (SP) is used and reduction of the ambipolar current is done by using hetero dielectric as a gate. Hence, various characteristics/properties and parameters of source pocket hetero dielectric double gate TFET (SP-HD-DG-TFET) are studied by varying the width of the SP by 4, 6, and 8 nm. By using the Silvaco TCAD, it is found that the current ratio decreases and SS increases with increase in the width of the SP. Hence, the lower value of the width of the SP is considered to be suitable for low power and high speed application.