부산대학교 도서관

Type I InP/InGaAs/InP double heterojunction bipolar transistors were fabricated using a simple mesa structure, where emitter junction widths have been scaled from 250 nm to 200 nm. These devices exhibit ƒ max in excess of 800 GHz, and ƒ τ = 360 GHz. Greater than fifty percent device yield was obtained by employing two 25 nm SiN x sidewalls to protect and anchor the refractory metal emitter contact to the emitter semiconductor. A hybrid dry and wet etch process is used to form a vertical emitter mesa, causing reductions in both the emitter-base gap resistance R gap and the spreading resistance beneath the emitter R b,spread , leading to an expected and observed increase in ƒ max . Peak HBT current gains β ≈ 21–33, BV ceo ∼ 4 V, BV cbo ∼ 5 V, and J e at low V cb is over 10 mA/μm 2 .