What are the different types of IGBT?

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Editorial Team - everything PE

Jan 10, 2023

There are two types of IGBTs - Punch Through IGBT or PT-IGBT also known as asymmetrical IGBT and Non-Punch Through IGBT or NPT-IGBT also known as asymmetrical IGBT. 

PT-IGBT comprises n- (drift), n+ (buffer), and p+ (anode) regions. The n- the region is optimized to meet the withstand voltage requirement. PT IGBTs, which are fabricated using epitaxial wafers, have a thick p+ collector region with high dopant concentration. In the conducting state, large amounts of carriers are injected from the collector to achieve conductivity modulation and thereby reduce the on-state voltage.

NPT-IGBT is designed with a thick n- drift region so that the depletion layer remains within the n- drift region even in the maximum electric field. Therefore, NPT IGBTs do not have an n+ buffer region that is required in PT IGBTs to reduce the expansion of the depletion layer. In addition, the NPT IGBT has a thin p+ region. And by varying the dopant concentration of this p+ region, the amount of carrier injection is controlled.

The difference between the two types of IGBTs are summarised in the table below:

PT-IGBT

NPT-IGBT

Has asymmetrical configuration

Has symmetrical configuration 

Has low conduction loss which increases with temperature

Has higher conduction loss which is independent of temperature

Not preferred for parallel configuration application circuits

Better parallel operation due to better temperature coefficient and shared heating dissipation

Offers less thermal stability

More Thermal stability

Low switching losses

Higher switching losses

Less rugged in short circuit failure mode

More rugged in short circuit failure mode

Lower lifetime

Relatively higher lifetime

Mostly used in DC circuits

Mostly used in AC circuits

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