Analysis of a power bipolar-mode JFET device by two-dimensional numerical simulation

The on-state and off-state behavior of a bipolar mode JFET device is analyzed by using a detailed 2-D numerical simulation. The numerical results show that the device has basically two modes of operation, namely a unipolar mode of operation when the gate bias is less than 0.4 V and a bipolar mode of operation when gate voltage allows a significant injection of minority carrier into the channel. The analysis clearly shows the role played by the conductivity modulation in changing the shape of the I-V curve from the triode-like shape to the transistorlike one, as well as the influence of the most significant structure parameters on the electrical performance of the device. The transition between the unipolar mode of operation and the bipolar one is governed by the minority carrier concentration in the channel, and this transition is also responsible for the change in shape of the output I-V curves. All the relevant features of the I-V curves belonging to the unipolar and the bipolar regimes are observed and explained in the numerical analysis, in particular, the transition between the exponential and linear drain voltage dependence of the current in the unipolar operation and the very low on-resistance below the knee in the bipolar operation.<
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