Research On Characteristics Of Enhanced P-GaN Grooved Gate HEMT Power Devices

The third generation semiconductor material represented by GaN has advantages such as large band gap width,high critical breakdown electric field,and large electron saturation drift velocity.High electron mobility transistors（GaN HEMT）based on GaN materials occupy an important position in the research of power switching devices due to their high frequency,high efficiency,high temperature resistance,and miniaturization.However,due to the widespread depletion effect of GaN HEMT,device safety and static power consumption suppression are extremely difficult to achieve.At present,the breakthrough of enhanced technical difficulties in GaN HEMT has attracted much attention and is expected to overcome the challenges faced by conventional depleted HEMTs.In addition,there is a problem of GaN buffer layer leakage leading to a decrease in device breakdown voltage during the preparation of enhanced HEMT,which seriously restricts the performance and reliability of enhanced HEMT devices.In response to the challenging challenges facing HEMT devices at present,this thesis conducts research on enhanced p-GaN groove gate HEMT power devices through simulation,device structure optimization,and epitaxial material doping,ultimately achieving effective suppression of static power consumption and significant improvement in breakdown voltage.The specific work is as follows:（1）Enhanced p-GaN groove gate HEMT device.Aiming at the challenging challenges of low security and high static power consumption of GaN HEMT devices,a new enhanced p-GaN groove gate HEMT device was proposed and simulated.AlGaN was chemically etched by MOCVD to obtain a depth of 5 nm and a length of2μm,a groove with a roughness of 1.82 nm,and factors such as growth temperature,time,and trimethylgallium（TMGa）flow rate are adjusted to achieve in situ growth of p-GaN.The feasibility of the enhanced p-GaN groove gate HEMT device has been verified by experiments,and the forward shift of the threshold voltage(V_TH=1.9 V)has been successfully achieved,which is basically consistent with the simulation results and effectively improves the safety of the device.In addition,the device exhibits excellent electrical performance,with a maximum output current of 227m A/mm,a conduction resistance R_ONof 13.54Ω.mm,and a breakdown voltage of600 V.（2）Enhanced p-GaN groove gate HEMT power devices based on buffer layer doping.Aiming at the problem of generally low breakdown voltage of GaN HEMT devices,high-power enhanced p-GaN groove gate HEMT devices have been developed.By adjusting the growth conditions of MOCVD such as growth temperature,V-III ratio,and reactor pressure,it is concluded that the V-III ratio is the main limiting factor for high carbon doping efficiency.At a carbon concentration of9×10¹⁸/cm³,a C₂H₄doped GaN buffer layer was prepared based on atmospheric pressure MOCVD,significantly improving the crystal quality of the buffer layer,making its surface smoother,and significantly reducing its roughness.A high voltage withstand GaN buffer layer was successfully achieved,and the breakdown voltage was raised to 2278 V,providing an effective way to implement enhanced GaN HEMT power devices.