PURPOSE: To reduce the effective base resistance during high speed operation bringing the high speed performances into full play by a method wherein an insulator layer is partly laid between base contact parts.
CONSTITUTION: A collector layer comprising N+ and N type GaAs 2, 3, a P type GaAs inner base 4 and a P type AlGaAs outer base 6 as well as N type AlGaAs 8∼10 and an N+ type GaAs emitter 11 are laminated on a semiconductor GaAs substrate 1; and an insulator layer is partly buried in the contact part between the base electrode 16 and the outer base 6. Through these procedures, when an insulator is laid between the half parts of contact part, the capacity C between electrode and base layer is halved in the insulator layer part; the contact resistance R is doubled if whole body is in ohmic contact; the base input impedance parallels 2R and ωC when actuated in the frequency of ω and the effective value thereof becomes smaller than the contact resistance R without fail if insulator is not provided so that the impedance may be substantially reduced to make the high speed operation feasible.
KATO RIICHI
MORITSUKA KOHEI
