Design Of High Voltage Termination Structure For Gallium Oxide Schottky Barrier Diode

Gallium oxide(Ga₂O₃)is an emerging ultra-wide band gap semiconductor material,has a large band gap of 4.8 e V and an ultra-high theoretical breakdown electric field of 8 MV/cm.At the same time,its Baliga figure of merit(BFOM)is 8 times of 4H-Si C and 4 times of Ga N.These superior properties enable gallium oxide Schottky barrier diode(SBD)to achieve ideal electrical properties in theory.In recent years,it has become a hot spot in global research.This paper focuses on the gallium oxide Schottky barrier diode,using simulation as the main means,and applying the semiconductor device simulation tool“Silvaco”to design devices with terminal structures such as the high-resistance region,field plate,beveled angle,and their composites,to explore the influence of optimization parameters and structures on device characteristics,emphasizing on reverse breakdown voltage,on-resistance,and Baliga figure of merit.We have obtained the following conclusions:First,understand the basic properties of gallium oxide and working principle of Schottky barrier diode.Proficient in“Silvaco”simulation tool,such as“Dev Edit”,“Athena”and“Atlas”.According to the material parameters and device characteristics of the gallium oxide Schottky barrier diode,the correct simulation physical models should be debugged and selected.These are key factors to ensure the accuracy of subsequent simulations.Second,use“Silvaco”simulation tool to design the basic structure of the gallium oxide Schottky barrier diode,and obtain the reverse breakdown voltage of-519V,on-resistance of5.68m??cm²,and Baliga figure of merit of 0.05GW/cm².It lays a foundation for the subsequent addition of various terminal structures on devices to obtain better electrical characteristics.Third,high-resistance terminal structures are simulated and designed into gallium oxide Schottky barrier diodes,including insulation,low doping,ion implantation and thermal oxidation.The effects of different types of high-resistance terminal structures on the electrical performance of the devices are explored.The results have shown that high-resistance terminal structures are very helpful to improve the reverse characteristics of devices,but increase the on-resistance of devices.Fourth,field plate terminal structures are simulated and designed into gallium oxide Schottky barrier diodes,including single-stage field plate,multi-stage field plates,and field plate trench composites.The effects of different field plate parameters and structures on the electrical performance of the devices are explored.The study has found that field plate terminal structures change the peak electric field of the devices from the surface of the gallium oxide to the surface of the insulation,so the insulation with a wonderful quality is necessary to prevent its premature breakdown.Field plate terminal structures have little effect on the forward characteristics of devices,which is very advantageous.As the length of the single-stage field plate increases,the reverse breakdown voltage of the device gradually increases,but the rate of increase is gradually not obvious.The multi-stage field plates terminal structure is very effective in alleviating the peak electric field of the insulation,is very significant on preventing the insulation from premature breakdown.Try to design a composite termination structure of trench and field plate to improve the breakdown voltage and Baliga figure of merit of the device.Fifth,the gallium oxide Schottky barrier diodes with beveled angle terminal structures are designed by simulation.Beveled angles contain 2°,30°,45°,60°,90°,120°and 150°respectively.Investigate the effect of terminal structures with different beveled angles on the electrical performance of the devices.Study has shown that smaller beveled angle such as 2°terminal structure can significantly improve the forward and reverse characteristics of the device.Then,try to design device with compound angle and field plate,and optimize the parameters to seek a larger reverse breakdown voltage and Baliga figure of merit.