The Fabrication And Structure Optimization Of AlGaN/GaN Schottky Barrier Diode

In recent years,as one of the third generation of semiconductor representatives,GaN material has become the research focus of research institutions and enterprises at home and abroad because of its important application value in the field of semiconductor lighting and power electronics.AlGaN/GaN heterojunction Schottky barrier diode?SBD?is an important member of wide band gap semiconductor devices.With its advantages of low conduction resistance,high voltage,fast switching speed and high thermostability,it has gradually become a key research object in power electronics and microwave communication domain.In this paper,the key technology of AlGaN/GaN SBD was optimized.The AlGaN/GaN SBD devices with different electrode structure were prepared and the electrical characteristics were tested.The AlGaN/GaN SBD model with floating metal rings was established and the device simulation was carried out.This work was supported by the project of 863Program?2015AA033305?and National Key R&D Program of China?Grant No.2017YFB0402800,2017YFB0402803?First,The main process steps in the process of AlGaN/GaN SBD are optimized.For ohmic electrode,the influence of Ti/Al ratio and Ti/Al thickness on specific contact resistivity was studied.For SiO₂ passivation layer,the effect of passivation layer on positive electrical characteristics and reverse leakage current of AlGaN/GaN SBD device was studied.For Schottky electrodes,the effects of annealing time and annealing temperature on characteristics of AlGaN/GaN SBD devices were studied.Then,combined with the optimized process parameters,the circular structure and multifinger-patterned AlGaN/GaN SBD with different electrode structure were prepared.The electrical characteristics of the device were tested.The effects of the electrode spacing,the size of the electrode and the number of finger on the positive and reverse electrical properties of AlGaN/GaN SBD were analyzed.The breakdown mechanism of the device is further analyzed by the test of the reverse breakdown voltage and the microscopic picture of the device after breakdown.Finally,the device structure of AlGaN/GaN SBD was optimized by Silvaco-ATLAS software,and the structure of AlGaN/GaN SBD device with floating metal ring was designed.The positive and reverse electrical properties of the devices with and without a floating metal ring were compared.the influence of the width of the floating metal ring on the forward and reverse electrical properties of the device was analyzed.the influence of the number of floating metal rings on the positive and reverse electrical properties of the device was studied.