A Suitable Approach to Assess Thermal Properties of GaN Power Bars

This paper describes the activities carried out to assess the thermal behavior of a Gallium Nitride (GaN) power bar grown on Silicon Carbide (SiC) substrate. The aim is to set up a reliable approach to extract an accurate value of the device thermal resistance (R th ), under different base-plate temperatures and dissipated power values. To this purpose, both Raman spectroscopy (RS) and photo-current (PC) techniques were experimentally applied to verify the results obtained from simulations based on finite element analysis. Such activity was carried out in the framework of a project aiming to develop a Solid State Power Amplifier (SSPA) for space applications, where thermal management is of primary importance. Even if with some differences, the comparisons between measured and simulated values have confirmed that both RS and PC techniques can be applied to experimentally verify the simulation's assumptions.