Research On GaN-on-si Lateral Power Rectifier

In the field of electric vehicle,data center and wireless charging,rectifier is widely applied in AC/DC(Alternating Current/Direct Current)Rectifier,DC/DC Converter and DC/AC Inverter circuits,and plays an irreplaceable role.With the continuous approximation of the Si theory limit,gallium nitride devices have unique advantages.Under the same operating voltage,the energy conversion efficiency of GaN devices is generally about 3-5% higher than that of Si devices.In addition,in the device working speed,the current mainstream Si based devices in the typical DC-DC conversion application,the maximum device can only reach to MHz working frequency.However,if a new wide band gap semiconductor GaN device is used,the operating frequency can reach 10~100 MHz.The increase of working speed of power switch can greatly reduce the volume of passive devices such as inductors and capacitors in power management system,so as to reduce the overall volume of power management system and make the equipment smaller and lighter.A new type of high performance GaN transverse power rectifier is proposed in this paper.The main contents are as follows:(1)the Hybrid Anode Diode(HAD)presented in this paper is characterized by the low resistance ohmic contact and the MIS grooved gate by short connection of Schottky metal to form the so-called mixed anode structure.Meanwhile,two sets of theoretical and feasible technology solutions are proposed to achieve the experimental preparation of HAD--conventional barrier(AlGaN 23nm)AlGaN/Ga N heterojunction fabrication technology and UTB(thin barrier)AlGaN/GaN heterojunction fabrication technology.(2)with Sentaurus TCAD simulation tools to optimize the structural parameters of the diode,especially the depth of the groove in the conventional barrier structure and the optimal value of the barrier layer thickness in the ultra thin barrier structure.The conventional barrier structure has an opening voltage of 0.2 V,and the opening voltage of diode with a thin barrier structure is less than 1.0 V,which has great advantages over traditional SBD.The reverse characteristic simulation of the device shows that the rectifier uses 1?A/mm leakage current as the breakdown standard and the voltage is up to 1000 V,while the conventional SBD is 522 V.(3)the author will introduce the process of diode preparation technology in detailfrom the wafer to the final devices with rectification function,analyse electrical properties of the final test device and the device's preparation technology and design idea will be evaluated and summarized.This work focuses on the traditional silicon based AlGaN/Ga N heterojunction diode rectifier to deal with the problems of high turn-on voltage and low reverse voltage capacity,using the new structure of transverse power rectifier and achieved by conventional barrier layer preparation technology and ultra thin barrier layer preparation technology.The open voltage of 0.3 V is obtained,showing 44% lower than traditional SBD devices,the maximum voltage of more than1000 V with 1?A/mm as the breakdown standard,while the SBD's breakdown voltage is only 513 V with 1?A/mm as the breakdown standard.The power rectifier produced by the thin barrier crystal wafer is further optimized in the open voltage.The actual test shows that the open voltage of 0.2 V is the lowest reported value at present.However,the growth quality of thin barrier layer materials has not yet been achieved breakthrough,and the breakdown voltage still needs to be improved.