非穿通型与穿通型平行平面结基于Chynoweth方法的新的设计表达式

The relations among the breakdown voltage,the width and the concentration of the voltage-sustaining layer for the non-punch-through(NPT) and punch-through(PT) abrupt parallel-plane junctions have been reestablished based on the ionization integral by the Chynoweth model,distinguished from the conventional results obtained by the Fulop model.The numerical calculation results indicate that the new expressions are more accurate than those in previous literature.While the breakdown voltage of the NPT case varied from 400 to 1600 V using the Chynoweth model,the value using the Fulop model is overestimated by 12%(478 V) to 18%(1895 V).For the PT case with optimum design of the specific on-resistance,when the breakdown voltage is varied from 400 to 1600 V,the width and concentration are from 81.0168%to 80.2416%and from 91.4341%to 91.6941%of those of the NPT cases,respectively.The relations between the specific on-resistance and the breakdown voltage for both the NPT and PT structures are also established.Simulation results by MEDICI show good agreement with the proposed expressions.     

4H-SiC p-n结基于精确碰撞电离模型的雪崩倍增因子研究

雪崩倍增效应是4H-SiC雪崩光电二极管、功率半导体器件等器件的关键机理。作为其中最重要的物理参数，雪崩倍增因子(M)的精确解析表达式目前未见报道。文章提出4H-SiC p-n结M的精确计算方法及其解析表达式。基于更准确的碰撞电离模型，通过MATLAB对4H-SiC单边突变结(p⁺-n)电子和空穴的碰撞电离积分(I)进行精确的数值计算，给出击穿电压(BV)随掺杂浓度的经验表达式，进一步提出电离积分随外加电压及掺杂浓度的拟合表达式。此外，对外加电压接近BV的情形进行细致的相对误差分析，表明电子电离积分受电场影响显著。对于雪崩光电二极管及功率器件较宽的BV范围，所提出的拟合表达式在外加反向偏压大于0.65BV时具有较高的精确度(相对误差小于5%)。     

埋超结层的电场分布的一个解析模型

An analytical model of the electric field distributions of buried superjunction structures,based on the charge superposition method and Green’s function approach,is derived.An accurate approximation of the exact analytical model of the vertical electric field is also proposed and demonstrated by numerical simulation.The influence of the dimension and doping concentration of each layer on the electric field is discussed in detail,and the breakdown voltage is demonstrated by simulations.