Study On Characteristics Of GaN Based Schottky Diode With Low Turn-on Voltage Based On Anode Metal Modulation

The schottky diode based on AlGaN/GaN heterostructure has the advantages of fast switching speed,high voltage resistance,high temperature resistance and radiation resistance,which can meet the requirements of high frequency and high power application scenarios such as high efficiency microwave radio energy transmission,and has gradually become a key research object in the field of power electronics.,however,the traditional planar AlGaN/GaN schottky diode turn-on voltage is difficult to reduce technical problem has become the important factors to limit its application,the groove combined with low work function metal anode structure can effectively reduce the device open voltage,but the conventional reactive ion etching process precision of deficiencies in the process of groove etching,etching damage big,this will not only cause open voltage fluctuations,but also harmful to reverse device electrical characteristics.Aiming at this prominent problem,this paper systematically developed a low-damage slow etching process method suitable for the groove structure,realized the low-opening voltage AlGaN/GaN schottky diode,effectively improved the process stability,and combined with theoretical simulation and epitaxial material optimization,further improved the device performance.The specific research results are as follows:Based on the core structure of the recessed anode,the effects of recessed etching depth on the device opening voltage and recessed etching damage on the device reverse characteristics have been studied in this paper.The experimental results show that the device opening voltage first decreases and then increases with the etching depth,and the etching damage will significantly increase the leakage current of the device.By reactive ion etching process of etching gas rate,cavity pressure and rf power fine regulation of etching conditions such as,developed a low damage slow etching process,realize the precise control,etching groove depth Angle improved significantly,etching damage effectively inhibit grooves anode AlGaN/GaN schottky diode,effectively reduce the open voltage and reverse leakage,and significantly improved the process repeatability and stability.In order to further reveal the working mechanism,improve device performance,first of all use Sentaurus TCAD simulation platform built groove type AlGaN/GaN schottky diode device model,studies the groove type AlGaN/GaN schottky diode under normal temperature and the characteristics of variable temperature direction,through the thorough analysis to the is after the device internal carrier and the situation of the current density and the distribution of the partial state of electric potential and electric field distribution of the device,reveals the groove type AlGaN/GaN schottky diode under normal temperature and temperature,the physical mechanism of the forward and reverse work.The effect of Fe doped Buffer layer on device leakage was studied.Secondly,on the basis of the optimized groove etching process,W metal with lower power function is used as the anode metal to further reduce the device opening voltage to 0.32 v and the sub-threshold swing amplitude is 64 m V/dec.The temperature variation and forward current transfer mechanism of the device are analyzed,and the experimental results are consistent with the simulation results.In conclusion,based on the low damage slow reaction ion etching process method,a relatively ideal groove structure can be prepared,and the groove AlGaN/GaN schottky diode with low voltage,low reverse leakage,good process repeatability and high process stability can be realized,which is of great significance for promoting its high frequency power application.