The Study For Steady State And Transient Thermal Simulation Of AlGaN/GaN HEMT Devices Based On Sentaurus TCAD

The GaN HEMTs(High Electron Mobility Transistors)devices show excellent performance in high-power,high-frequency applications due to the wide range of electrical advantages of third-generation semiconductor materials.As a key component of microwave power amplifier application in radar and communication technology,GaN HEMTs devices have important strategic significance in military,national defense and communication fields.At the same time,the self-temperature rise of the device at work directly affects the performance of the device,so the study of the temperature characteristics of the device is extremely important.In this paper,the GaN HEMTs device was used as a sample.The samples were measured by scanning electron microscopy and laser focusing microscopy.The temperature of the infrared thermal imager was used as the verification.The temperature characteristics of GaN HEMTs devices were studied by means of numerical simulation.The research work includes a few aspects as follows:1?By selecting CREE's GaN HEMTs device as the research object,we opened the cap and sliced.The samples were measured by scanning electron microscopy and laser focusing microscopy.The Sentaurus TCAD numerical model was established by using those geometrical parameters.In order to reduce the simulation time,a twodimensional finite element model is adopted.At the same time,to ensure the effectiveness of the model,the infrared thermal imaging data was collected for verification.The infrared thermal imager acquisition space resolution is 7?m.We set and calculated the 7?m average temperature near the gate heat source.The temperature is compared with the infrared and simulation to further verify the effectiveness of the model.Thus,the accuracy of the model was ensured.2?Using the established accurate model,the influence of the parameters on the thermal characteristics is studied by changing the parameters of the GaN HEMTs device.The thermal characteristics of the device under different gate length,different gate spacing,different Ga N layer thickness,different substrate width and different substrate thickness were discussed respectively.The simulation results were analyzed.The results show that:(1)The peak temperature of GaN HEMTs devices is heavily dependent on the gate length of the device.In order to improve the high-frequency characteristics of the device,the device's gate length should be carefully designed;(2)In this example,the thermal coupling effect of the GaN HEMTs device is greatly influenced by the gate pitch,especially when the gate pitch of the device is less than 30 ?m.The peak temperature of the device increases rapidly with the gate pitch decreases;(3)Considering the stress and defects of the GaN layer,it should also consider the influence of the different thickness of the GaN layer on the heat dissipation of the device;(4)Unlimited expansion of the device substrate width to improve heat dissipation cannot bring good results.(5)In order to achieve a smaller substrate thermal resistance,too thin substrate thickness design is not appropriate.Because during the device production process,it may cause devastating consequences.3?Firstly,we described the selection of the finite element model and the control of the pulse signal in the Sentaurus TCAD software.The transient iteration in the transient simulation is used to solve the continuity problem.The transient thermal characteristics of the device were studied at different frequencies: 1kHz,5kHz,10 kHz and 100 kHz and different duty cycle: 30%,50% and 70% respectively.The following conclusions can be drawn from the analysis:(1)the time of stable temperature distribution at different frequencies is different.The higher frequency,the time to steady state is shorter;(2)the device has different highest temperature at different frequencies signal.The higher frequency,the temperature is lower;(3)when the lower frequency of signal is loaded,the more heat is accumulated.The result is that there has higher temperature when the device is steady-state;(4)when the higher duty cycle of the frequency signal applied to the device,it has higher temperature value.