On the quasi-saturation behavior of a novel vertical power MOSFET with self-aligned gate

A comparative analysis of HWFET™ with two different drain dopings is presented, demonstrating the dominant role of the drain conductivity in determining the device´s quasi-saturation (QS) behavior. Numerical simulation shows that the E-field in the drift region increases with the drain voltage. The lightly-doped-drain device is shown to exhibit a higher peak E-field and larger e^- velocity than its heavily doped counterpart. The correlation between the severity of QS and the pace at which electron reaches the saturation velocity is established.