In this paper, we report the fabrication and device characteristics of InP/InGaAs double heterojunction bipolar transistors (DHBTs) with buried SiO₂ wires. The SiO₂ wires were buried in the collector and subcollector layers by metalorganic chemical vapor deposition toward reduction of the base-collector capacitance under the base electrode. A current gain of 22 was obtained at an emitter current density of 1.25MA/cm² for a DHBT with an emitter width of 400nm. The DC characteristics of DHBTs with buried SiO₂ wires were the same as those of DHBTs without buried SiO₂ wires on the same substrate. A current gain cutoff frequency (f_T) of 213GHz and a maximum oscillation frequency (f_max) of 100GHz were obtained at an emitter current density of 725kA/cm².