A new InP/InGaAs/InP DHBT structure with high carbon (C)-doped base was optimized and grown successfully by gas source molecular beam epitaxy (GSMBE) in this work. The C-doping concentration is 3 x 10(19) cm(-3) with carrier mobility of 66.3 cm(2)/V s. Characteristics of C-doped InGaAs materials were investigated. High quality InP/InGaAs/InP DHBT structural materials were obtained. The InP/InGaAs/InP DHBT device with emitter area of 100 x 100 mu m(2) was fabricated. The open base breakdown voltage (VBCEO) of 4.2 V and current gain of 60 at V-CE of 3.0 V were achieved. All these results prove the material is suitable for DHBT device fabrication. (c) 2013 Published by Elsevier B.V.