Study On Single Event Burnout Effect Of Gallium Nitride Power Devices By Pulsed Laser Simulating Experiment

Single event burnout(SEB),induced by high-energy ionizing particles,is a prominent radiation effect for power devices used to aerospace applications,and the resulting catastrophic failures make it impossible to guarantee the normal operation of power systems.Gallium Nitride(GaN)power devices have a promising potential in space power supplies due to their superior physical properties.The use of pulsed laser technology can provide a powerful contribution for the GaN power devices SEB research.In this paper,we present concretely the radiation effects of GaN power devices and the development of experimental techniques.Meanwhile,the significance of the research using pulsed laser is elaborated.With the existing basic conditions,it develops the laser quantitative assessment technique of SEB for the GaN power devices,and examines the evolution mechanism of SEB by laser testing.In addition,based on the experimental results of different GaN power modules,protection recommendations for practical application requirements are proposed.The specific research contents and conclusions are as follows:(1)A systematic study of the quantitative laser assessment technique of SEB for GaN power devices is undertaken.For different device structures,it improves the effective energy transfer model with the front-incidence laser,and establishes the effective energy transfer model with the back-incidence laser.On the basis of two-photon absorption mechanism,incident wavelength of the laser,reflectivity and transmission coefficient of the device material,and other general parameters are determined in the models.The equivalent models of the pulsed laser effective energy and the heavy ion linear energy transfer(LET)are verified through a variety of devices experiments.(2)The evolutionary mechanism of SEB for GaN power devices is studied,mainly including the low-voltage degradation and high-voltage burnout in irradiated devices.Comparing the changes of device electrical characteristics in laser experiments and heavy ion experiments,based on the laser effective energy transfer models and simulation tests,the reasons for the degradation of device electrical properties during irradiation in low-voltage operations are analyzed.For the direct burnout of the device during high-voltage operations,the burnout pattern is summarized and sensitive area is located.Then it views the transverse and longitudinal damage patterns by microscopic observation,determining the dominant factors of SEB and the formation process of leakage paths by the electrical performance of the irradiated device before and after damage.(3)Experiments are conducted to evaluate SEB of two GaN power modules oriented to application requirements.For a GaN power module based on normally-off devices,the upper limit of burnout triggered by radiation energy and switching frequency are tested to analyze its suitability for space mission applications.Different components in the cascade circuit are tested separately to analyze their failure triggers under the radiation environment,which verifies that the normally-on GaN device in the power module has a better anti-radiation capability.Furthermore,relevant protection recommendations are made for the easily burnout parts.These will provide a reference for ensuring the safe operation of the devices in the aerospace environment.