The electric field distributions along A–O₁–B–C–O₂–D around the trench of the three types of the trench MOSFETs with the structure parameters as listed in Table 2. (The doping concentrations N_d, N p i and N n i of trench MOSFET1 are 4.5 × 10¹⁵ cm⁻³, 3.3 × 10¹⁶ cm⁻³ and 5.0 × 10¹⁵ cm⁻³, respectively. The doping concentration N_d of trench MOSFET2 and MOSFET3 is 4.3 × 10¹⁵ cm⁻³ and 3 × 10¹⁴ cm⁻³, respectively. Breakdown voltage of the trench MOSFET1, MOSFET2, and MOSFET3 is 588 V, 432 V and 311 V, respectively.)