Research On The High Power Electromagnetic Damage Effect And Mechanisms Of GaAs PHEMT And GaN HEMT

High electromagnetic pulse（HPEM）is a high power,high intensity,high frequency electromagnetic environment,it can easily couple into the internal electronic system and cause interference,damage to electronic and electric system,further makes the system failure even paralysis.With the development of high power electromagnetic pulse source,the threat of electronic system is increasing day by day.Along with the continuous development of microelectronics technology,the integration of semiconductor devices has been improved,and the power consumption and the characteristics size continuously reducing which increases the electromagnetic sensitivity of electronic systems.Semiconductor devices are the basic unit of electronic systems,it is very important to explore the effect law,failure mode and failure mechanism of the device under the strong electromagnetic pulse.In this paper,the method of numerical simulation,theoretical analysis and effect experiment are combined to study the effect and mechanism of typical RF front-end sensitive devices which is GaAs pHEMT under Ku and L band HPM.The effect of EMP damage on the pulse width of the typical GaN HEMT is studied,and the structure is optimized under the DC stress.The main research contents and results are as follows:1.A two-dimensional electro-thermal model of AlGaAs/GaAs pHEMT is established by Sentaurus-TCAD based on 0.25μm technology.Based on the experimental data,the model corrected the parameter of the thermal conductivity and specific heat under high temperature,and obtained the DC characteristics curves.The damage effect of Ku band HPM through"front door"coupling path is studied by transient simulation.Simulation results predict that the damage of GaAs HEMT is due to the introduction of large electric field and high current under HPM,which leads to the increase of temperature under the action of intrinsic excitation and avalanche breakdown.Continuous high temperature leads to a current channel near the source side of the device gate,which leads to the short circuit of the gate,so the HEMT failed.Furthermore,the effect of gate voltage and drain voltage on the HEMT damage effect is simulated,and the effect law and empirical formula of the burning time with the change of gate and drain voltage are acquired.2.Based on the established HPM effect simulation model of the AlGaAs/GaAs pHEMT,the L band HPM damage effect is analyzed through the study of the distribution of physical quantities in the device.Research shows that under the action of L band HPM,the temperature within devices behaves as periodical increasing–decreasing–increasing,according with the signal cycle,a temperature appears one peak value in a signal cycle,that is the temperature increases during positive half cycle and then decreases during negative half cycle.When the local temperature within the device is high enough（>750K）,the current increase sharply due to the intrinsic excitation of GaAs material,then the device temperature increase rapidly up to burnout.The cylinder under gate near the source side is most susceptible to damage.3.The HPM injection experiment of GaAs HEMT LNA in Ku band and L band was carried out,and the results were compared with the simulation results of the third chapter.Firstly,the construction of the experimental platform,the selection of damage criterion and the experimental procedure are introduced.Then the"front door"injection experiment was carried out.Finally,the failed samples was analyzed by using the transistor tester,scanning electron microscope,energy dispersive spectrometer,and the damage mechanism of LNA was given.The results show that both the Ku band and the L band,the damage of LNA is caused by the burning of the first stage GaAs HEMT,and there is no obvious abnormality in the second stage HEMT.It is found that there is a thermal breakdown point near the source of the first gate electrode by the metallographic microscope and scanning electron microscope.The experimental results are consistent with the simulation results.4.A two-dimensional electro-thermal model of the typical silicon based GaN high electron mobility transistor induced by EMP is established with the device simulator Sentaurus-TCAD by combining polarization effect,mobility degradation in high electric field,avalanche generation effect and self-heating effect.By analyzing the variations of device internal distributions of the electric field,the current density and the temperature with time,a detailed investigation of the damage mechanism and the threshold of the AlGaN/GaN HEMT under the injection from gate electrode is performed,that taking the EMP with the rising-edge of 1ns,power of 33dBm as an example.Under the injection of EMP,the maximum temperature keeps increasing,and the process is divided into three stages which present a tendency of“rapid-slow-sharp”till burn-out.When the temperature be equal or greater than 2000K,a positive feedback is formed between the hot electron emission and the increase of temperature which causes temperature a sharp increase till burn-out.The cylinder beneath the gate near the source side is the location of maximum value both for electric field and current density,hence it is susceptible to damage because of heat accumulation.Finally the dependences of the EMP damage power,P,and the absorbed energy,E,required to cause the device burn-out on the pulse width are obtained in the nanosecond region by adopting the data analysis software.It is demonstrated that the damage power threshold decreases but the energy threshold increases slightly with the increase of pulse-width.5.The berakdown characteristics of GaN HEMT devices in the off state are studied.Based on the experimental results,the impact ionization coefficient of GaN material is modified.The dependence of breakdown voltage on concentration(from 2×10¹⁶ cm^-3 to 5×10¹⁹ cm^-3)of the cap layer is discussed by analyzing the effect of the GaN cap layer.Simulation results indicate that P-type doping could achieve higher breakdown voltage than N-type GaN cap because the net ionized negative space charge（off-state）in cap layer can modulated surface electric field of HEMT which an achieve a better RESURF effect.A novel structure is proposed by applying the buried P-type layer in GaN buffer which widening the deplete region and introduces a new electric field peak between gate and drain electrode.The breakdown voltage of the proposed structure is 640V which is increased by 12%in comparison to UID-GaN/AlGaN/GaN HEMT.