Spatially resolved heavy ion microprobe testing of lateral Ga2O3 MOSFETs

Ultrawide bandgap β-Ga2O3 has been intensively researched for power electronics applications after the first demonstration of high quality MOSFETs and MESFETs in 2012. Testing of β-Ga2O3 transistor structures under heavy ion irradiation is relatively unexplored despite its criticality in developing next-generation radiation-hardened electronics for space applications. Single ion irradiation was performed with 192 MeV Ar and 1182 MeV Au and a lateral spatial resolution of ∼0.5 μm to map the electrical characteristics of β-Ga2O3 MOSFETs as a function of irradiation position and identify the most sensitive regions of the device. This work determines that standard Ga2O3 MOSFETs are not susceptible to single event burnout under in operando irradiation under an applied field of 0.83 MV/cm for Ar irradiation as well as an applied field of 0.07 MV/cm for Au irradiation. Successive irradiations reveal transient increases in drain current associated with threshold voltage shifts attributed to defect generation/ionization in the top atomic layer deposited-Al2O3 dielectric or the semi-insulating Ga2O3 substrate and subsequent thermal relaxation. Fitting in situ transfer curve data reveals that the dominant effect under heavy ion irradiation is the activation of the parasitic channel via the generation of net positive charge at the buffer–substrate interface.