Optimization Of α-Ga₂O₃-based Schottky Devices

Gallium oxide（Ga₂O₃）,as a new ultra-wide band gap semiconductor material,has attracted much attention in the field of power electronic devices due to its excellent characteristics of 4.9eV～5.3eV band gap,such as ultra-high Baliga value,high breakdown voltage and so on.In a variety of Ga₂O₃ isomers,α-Ga₂O₃ is a kind of sub-stable phase,compared with the stableβphase,has higher band gap width,Baliga optimal value and breakdown field strength,and similar to gallium nitride,sapphire hexagonal crystal,so it has great potential in the performance of power semiconductor devices and process integration.Schottky diode（SBD）has been playing an important role in many power devices,and the excellent characteristics ofα-Ga₂O₃ are of great value to improve the voltage withstand performance of SBD and inhibit the reverse leakage current,which has gradually become the current research focus.This paper uses Silvaco TCAD simulation software to model and study schottky diode devices with different structures.For a newα-Ga₂O₃ material,we have determined the electrical model of the device and some parameters of the material through repeated simulation and calibration and comparison with experimental reports.Two-dimensional and three-dimensional models ofα-Ga₂O₃ SBD devices are established respectively.In the optimization of the two-dimensional model,the current platform after the initial breakdown was found in the reverse characteristics of the device.By adjusting the parameters of impact device:doping concentration and thickness of the drift region,field plate width,number plate,finally concluded that the current platform in breakdown characteristic increased with the increase of the thickness of the drift region,but for the dependence of the doping concentration change is weak,divided into a number plate of the electric field distribution can be optimized and improve the breakdown voltage of the device,the maximum electric field for more than 10MV/cm.In the optimization of the 3D model,the device thickness along the Z direction is added.By constantly adjusting the anode structure and combining the device performance shown in the parameters of the 2D model,the research results show that the three dimensional SBD device with seven-field plate structure has the best breakdown voltage and electric field distribution characteristics,and its maximum breakdown voltage is about 3.4kV.The Baliga value is as high as1.1GW·cm^-2.