A superjunction structure using high-k insulator for power devices:theory and optimization

A superjunction（SJ） structure using a high-k（Hk） insulator is studied and optimized by using an analytic model.Results by using the proposed model match well with that of numerical calculations.Numerical calculation results show that,only needing an Hk insulator with a permittivity of ε_I=5ε_S,the optimum specific on-resistance of the MOSFET applying the proposed structure is about 8%-20%lower than that of the conventional SJ-MOSFET with V_B = 200-1000 V.An example with V_B = 400 V shows that,the permissible error range of doping concentration of the p-region to maintain above 80%of V_B is from —37%to ＋32%for the former and is only from-13%to ＋13%for the latter.

A simulation study on a novel trench SJ IGBT

An overall analysis of the trench superjunction insulated gate bipolar transistor（SJ IGBT） is presented and a detailed comparison between a trench SJ IGBT and a trench field stop IGBT is made by simulating with Sentaurus TC AD.More specifically,simulation results show that the trench SJ IGBT exhibits a breakdown voltage that is raised by 100 V while the on-state voltage is reduced by 0.2 V.Atthe same time,the turn-off loss is decreased by 50%.The effect of charge imbalance on the static and dynamic characteristics of the trench SJ IGBT is studied, and the trade-off between parameters and their sensitivity versus charge imbalance is discussed.

Edge induced band bending in van der Waals heterojunctions:A first principle study

The dangling bond free nature of two-dimensional(2D)material surface/interface makes van der Waals(vdW)heterostructure attractive for novel electronic and optoelectronic applications.But in practice,edge is unavoidable and could cause band bending at 2D material edge analog to surface/interface band bending in conventional three-dimensional(3D)materials.Here,we report a first principle simulation on edge band bending of free standing MoS2/WS2 vdW heterojunction.Due to the imbalance charges at edge,S terminated edge causes upward band bending while Mo/W terminated induces downward bending in undoped case.The edge band bending is comparable to band gap and could obviously harm electronic and optoelectronic properties.We also investigate the edge band bending of electrostatic doped heterojunction.N doping raises the edge band whereas p doping causes a decline of edge band.Heavy n doping even reverses the downward edge band bending at Mo/W terminated edge.In contrast,heavy p doping doesn’t invert the upward bending to downward.Comparing with former experiments,the expected band gap narrowing introduced by interlayer potential gradient at edge is not observed in our free-standing structures and suggests substrate’s important role in this imbalance charge induced phenomenon.