In this paper, a novel technique of variation doping profile in collector region for trench IGBT is proposed. The collector region is segregated in three sections such that the section with higher concentration lies towards emitter side while section with lower concentration lie towards gate side. The presence of lightly doped collector section increases the recombination rate by injecting lesser charge carrier leading to reduction in carrier lifetime. This effect further improves turn-off process for proposed device. However, due to increased recombination rate, collector current density reduces. But, this reduction is counter balanced by heavily doped collector section which injects higher charge carriers and maintains current flow through proposed device. The electrical characteristics of proposed and conventional device is simulated and analyzed. It is inferred that proposed device exhibits 48% reduction in turn-off time further minimizing energy loss by 53.3%. The lower doping profile of collector region also reduces corner electric field but due to p ++ -col section the net electric field increases hence, improving the breakdown voltage by 8.7%. Additionally, proposed structure exhibits 16.7% increment in Baliga figure of merit as compared to conventional design.

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The performance of a superjunction trench-insulated gate bipolar transistor with variable vertical doping in the epitaxial region along with variation in the collector layer is investigated. The concept of vertical variation transfers the avalanche multiplication point from the epitaxial edges to the middle of the pillar. The proposed device offers increased effective doping in the drift region, which reduces the on-state voltage (V on ) without any degradation in the breakdown voltage. Furthermore, the horizontal doping variation in the collector layer supports the phenomenon in two ways: the left section of the collector layer reduces V on whereas the right portion enables an efficient discharging path, which allows improved switching performance. In addition to this, a reduction in the gate to collector charge (Q GC ) is observed because of the presence of a lightly doped n-region below the gate terminal. A two-dimensional numerical simulation revealed that the proposed device offers a 15.30% reduction in Q GC compared with the conventional device. The structural modification offers a 40% reduction in turn-off time, resulting in a reduction in turn-off energy loss (E off ).

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