Effects of rapid thermal annealing on bias-stress-induced base leakage in InGaP/GaAs collector-up heterojunction bipolar transistors fabricated with B ion implantation

The effects of rapid thermal annealing (RTA) on bias-stress-induced base leakage were investigated in InGaP/GaAs collector-up heterojunction bipolar transistors (C-up HBTs) fabricated with boron ion implantation. C-up HBTs annealed at 700 degrees C for 1 s had negligible leakage, while non-annealed C-up HBTs had leakage (with an activation energy, E-a, of 0.17 eV) that exponentially increased with bias time. Because this E-a is almost the same as that of the hole traps (0.25 eV) observed in the InGaP emitters of non-annealed C-up HBTs, we attribute the leakage to hole tunneling from bases to emitters. By reducing the initial trap density using RTA, we stabilized current gain even after 1,030 h of testing at a junction temperature of 210 degrees C and a collector current density of 40 kA/cm(2).