Development of low defect, thermally dissipative and capacitively isolated GaN semi-insulating platforms for power amplifier modules

"To provide increased power, bandwidth and power added efficiency to current transmit/receive (T/R) modules for X-Band radar systems, GaN-based high-power amplifiers are needed to replace current GaAs-based systems. To meet a target output of 30 watts permodule at 10GHz proper thermal heat dissipation and capacitive isolation must be integrated into the GaN amplifier modules. Therefore, an appropriate buffer layer platform will be a critical issue in the development of these next generation modules.SiC substrate platforms offers good thermal dissipation, and at first glance appears like an appropriate choice. However, micropipes in SiC substrates compromise yields; more importantly, capacitive coupling, due to high background carrier concentration,remains a serious issue without a clear immediate solution.Thick GaN buffer layers are an alternative approach. The thermal conductivity of GaN is sufficient for thermal dissipation. While GaN is typically n-type in the low 1E17/cm3 range, CBL Technologies, Inc. has developed a semi-insulating GaN technology. Afurther benefit of the GaN buffer layer is the improved material quality and associated transistor lifetime performance. Based on thick GaN layers grown by hydride vapor-phase epitaxy (HVPE), this platform will provide both the necessary thermaldissipation and capacitance isolation for GaN-based X-Band radar systems. modules. Therefore, an appropriate substrate or buffer layer plat