Improved performances of a two-step passivated heterojunction bipolar transistor

An interesting InGaP/GaAs heterojunction bipolar transistor (HBT) with a two-step passivated (ledge structure and sulfur treatment) process on the base surface has been fabricated and studied. Based on the two-step passivation, improved transistor characteristics including the specific contact resistances ρ C , sheet resistances R sh , base surface recombination current density J SR , base current ideality factor n B , and microwave performances are obtained. Furthermore, the device with two-step passivation reveals the better thermal stability on ρ C , R sh , and n B than the devices with and without ledge structure. Therefore, the two-step passivation method can be employed for high-temperature and low-power electronics applications.