On the analogy of the potential barrier of trenched JFET and JBS devices

摘要

4H-SiC Trench Junction Barrier Schottky (TJBS) diodes are good candidates for ultra-high voltage applications when low doped epilayers are required. In that case, electric fields of p(+)-n junctions deeply extend under the Schottky contact which may induce a potential barrier at thermal equilibrium condition, similarly to what happens into the channel of Trench Junction Field Effect Transistors (TJFET). For the first time, the analogy between potential barriers of 4H-SiC TJBS and TJFET devices is in depth investigated by using an original analytical model. For both devices, the model allows an accurate analysis of the potential barrier height into the channel as a function of the channel width, of the p(+)-region and trench depths, of the doping concentration and of the reverse voltage. Since the model is also capable to calculate the reverse diode current of TJBS until the vanishing of the potential barrier, it is used to explain the intrinsic differences of devices as the non-monotonic reverse behaviour of TJBs with the depth of the trenched mesa. The accuracy of the model is verified by comparisons with numerical simulations. The model makes a further contribution to the understanding of the role of p(+)-regions on TJBS performance. (C) 2016 Elsevier Ltd. All rights reserved.