Research on Single Event Burnout of GaN Power Devices with Femtosecond Pulsed Laser

The femtosecond pulsed laser is used to study the quantitative evaluation technology of the single event burnout (SEB) effect in GaN power devices. In this work, we establish two pulsed-laser effective energy transmission models for different device structures, analyzing and verifying the equivalent relationship between the effective laser energy and the heavy ion linear energy transmission (LET). The critical parameters of models are confirmed, including laser parameters and device parameters. It can be obtained that, the materials passed by laser have no loss of energy at the wavelength of two photon absorption (TPA), but the interface reflectivity between the layers should be mainly considered. Meanwhile, the parameters are corrected by the laser multiple reflections between the interfaces, and the laser energy of the second reflection of the metal layer is considered. These measures can be used to reduce the error of the effective energy in the device active area. In addition, we validate the models with experiments. A gallium nitride high electron mobility transistor (GaN HEMT) and a schottky barrier diode (SBD) power device are chosen to carry out the irradiation experiments by a femtosecond pulse laser, so that the energy thresholds of SEB and the ratios of effective laser energy to incident laser energy can be determined. We calculate the SEB value of the laser equivalent LET threshold with two incident wavelengths to verify the equivalent relationship between the theoretical calculation value and the actual measured value. When the laser is incident from the back of the device, the greater TPA wavelength is more affected by the secondary reflection of the metal, so a smaller TPA wavelength is ideal for testing. However, the effective energy transmission model of the frontal incident laser have no need to account for the differences in results due to laser wavelengths. We suggest that the effective energy transmission models with the frontal incidence is more convenient. This work not only provides effective support for the laser quantitative evaluation of the SEB in GaN power devices, but also is beneficial to the design and verification of anti-radiation reinforcement.