With characteristics of 4H-SiC,a double base epilayer 4H-SiC bipolar junction transistors(BJTs) is investigated.By analyzing build-in electric field in the base region and the base transit time,the device is numerically calculated in two-dimensional models according to orthogonal experiments.A mean range analysis is made to find optimized structure of 4H-SiC BJTs.It shows that common emitter current gain with negative temperature coefficient is about 72 and it remains high in a wide range of collector current.

We present a quadrature method for mixed boundary integral equations of stable problems,which provides high accuracy and less complexity.Discrete equations are solved in parallel according to the coarse mesh partitions.Approximations with high accuracy are obtained by splitting extrapolation methods based on multivariate asymptotic expansion of errors.Besides,a posteriori asymptotic error estimate is derived.