Superjunction physics, from first principles to system impact.
A structured guide to charge balance, depletion, electric-field distribution, breakdown, conduction loss, switching behavior, process architectures and wide-bandgap extensions.
1. Conventional drift region
In a conventional high-voltage silicon MOSFET, the drift layer must balance blocking voltage against resistivity. Increasing doping reduces resistance but can compromise breakdown.
2. Add alternating pillars
Superjunction structures introduce alternating P and N regions. Their charge balance allows the drift region to deplete laterally and vertically during blocking.
3. Shape the electric field
With good charge balance, the field distribution can become more uniform, increasing usable breakdown capability for a given drift-region resistance.
The numbers engineers actually compare.
| Parameter | Why it matters | Watch-outs |
|---|---|---|
| BV / VDS | Blocking capability | Transient overshoot, temperature, margin |
| RDS(on) | Conduction loss | Temperature, package, current distribution |
| Qg | Gate-drive energy / switching behavior | Driver resistance and operating conditions |
| Qoss | Output-capacitance related switching loss | Strongly topology and voltage dependent |
| Qrr / trr | Reverse recovery behavior | Topology, current and temperature |
| FOM | Quick technology comparison | Never substitutes for application testing |
From silicon SJ to wide-bandgap charge engineering.
Silicon SJ
Mature, high-volume technology for offline PFC, LLC, flyback and industrial power supplies.
SiC superjunction
Research and commercialization efforts target the high-voltage frontier, especially around 1200V and above.
Intrinsic polarization SJ
III-nitride polarization can create charge-balanced structures without conventional intentional doping.