Research On High Freqency Of GaN HEMT

GaN HEMTs as the third generation of wide bandgap semiconductor material devices have abvious advantages at the aspects of high temperature,high frequency,high power,and so on.They were widely used in mobile communication,radar system,power electronics,microwave power,aerospace,and other fields.The background of paper was simply stated,Development advantsges of GaN materials and development history and research status of GaN HEMT were elaborated.Properties of GaN and AlGaN materials,AlGaN/GaN HEMT device structure and working principle were summarized.The SILVACO ATALAS software was used to set up the device mode and the device frequency was improved for three aspect.First,through theoretical calculation and device simulation of AlGaN/GaN HEMT devices of the electron mobility,conductive channel,direct current and transient properties,from micro to macro analysis of the whole working process.The capacitance changing and dischanging time was optimizated by changing the AlGaN layer of doping concentration and doping layer thickness on device.Second,AlGaN and different component In of InxGa1-xN were added as back barrier in AlGaN/GaN HEMT devices,which output and transient characteristics were sdudied,in order to improve the frequency of devices.Third,the new materials of In_xAl_1-xN/GaN HEMT devices were exploratory researched,through the transient simulation,different components In effect on the frequency was anlysized from the aspects of time,the appropriate simulation results was taken,the doping concentration was controled,the device frequency was further improved.The results were shown that,when the grid votage of AlGaN/GaN HEMT was 3V and the AlGaN layer doping concentration was1.24×10¹⁹cm^-3,AlGaN/GaN heterostructure electron mobility was arrived to maximum value,capacitor charging time the shortest,capacitor charging and discharging time also to achieve the shortest,so as to make the device increased frequency.When AlGaN doping layer thickness was,the charging time of capacitor was the shortest,capacitor charging and discharging time the shortest,the device frequency was improved.When back barrier was joined,device output characteristic was obvious enhancement,capacitance charging and discharging time was shorten,device frequencywas improved.Output device characteristics and capacitor charging and discharging time were the optimal for 10 nm to AlGaN/GaN heterostructure interface with thickness of 7 nm AlGaN back barrier and 5 nm to AlGaN/GaN interface with thickness of5 nm In_xGa_1-xN back barrier.And with the increase of the In compnent,output characteristic of device gradually strengthened.For different In components In_xAl_1-xN/GaN HEMT devices,output current decreases with increase In components of In_xAl_1-xN,when the In components was arrived to 55%,the device capacitance charging and discharging time was the shortest.