An efficient heat-spreader design, demonstrated on n-p-n InGaP/graded InGaAs base/GaAs collector-up heterojunction bipolar transistors (HBTs) for the first time, is proposed to achieve high speed and thermal dissipation performances. The collector-up HBT, with a graded InGaAs base, has been successfully fabricated using a three-stage selective-area-regrowth technique. A unity-gain cutoff frequency f(T) = 55 GHz and a maximum frequency of oscillation f(max) = 74 GHz were obtained from prototype devices with a large collector area of 3.5 x 40 mu m(2). Moreover, through proper thinning process, the maximum junction temperature and thermal coupling within the transistors were effectively decreased. It is shown that the thermal management for power amplifiers, based on the developed HBT, used in next-generation cellular phones can be enhanced. (C) 2012 Elsevier Ltd. All rights reserved.