Simulation And Optimization Of Vertical Ultra Wide Band Gap Schottky Diodes

Gallium oxide（Ga₂O₃）,as a new type of semiconductor material,has become a current research hotspot due to its ultra-wideband gap（4.9e V-5.3e V）,high Bari plus Value,and other characteristics.In different crystal phases of gallium oxide materials,α-Ga₂O₃is a metastable phase,relative to the stable stateβCompared to sapphire,it has a higher bandgap width,Baliga figure of merit,and breakdown field strength.At the same time,due to its crystal structure similar to sapphire,it has great advantages in improving the performance of power semiconductors and higher process integration.Schottky barrier diode（SBD）is widely used in semiconductor power devices.The excellent performance ofα-Ga₂O₃itself has great potential for improving the withstand voltage performance,switching speed,and other aspects of SBD,thus receiving widespread attention.This thesis uses Silvaco TCAD simulation software to establish SBD models with different structures,and analyzes and studies the models.Regarding the use ofα-The Ga₂O₃material was repeatedly searched for relevant literature to establish the model parameters of the material,and compared with relevant experimental reports to establish the device physics and structural model for this study.This thesis establishes a two-dimensional model of gallium oxide SBD.After establishing the basic electrical structure of the device,preliminary optimization was carried out on its main structural parameters.On this basis,the influence of silicon dioxide buried layer on the device’s voltage withstand characteristics was studied.By observing the electric field distribution and reverse I-V characteristics of the device,it was found that the addition of a layer of silicon dioxide can effectively alleviate the electric field spike effect and improve the device’s withstand voltage performance.After optimizing the buried layer parameters,the device’s withstand voltage performance can reach 4600V.Continuing to add the second layer of silicon dioxide buried layer will slightly improve the device’s withstand voltage performance,but its position and thickness have little impact on the withstand voltage performance.On the basis of a single-layer silicon dioxide insertion layer,p-type nickel oxide（Ni O）is added to the contact position of the anode Schottky to form a heterojunction type barrier device with n-type Ga₂O₃,further improving the withstand voltage performance.By studying the effects of doping concentration,thickness,drift zone thickness,and fin structure of p-type nickel oxide on forward and reverse characteristics,the optimized heterojunction structure SBD device can withstand voltage up to 4800V.