%0 Journal Article %J Solid-State Electron. (UK) %D 1995 %T On the design of composite-collector HBTs %A Ghodsian, B %A Pulfrey, D L %A Abid, Z %A McAlister, S P %K gallium arsenide;heterojunction bipolar transistors;III-V semiconductors;indium compounds;semiconductor device models; %P 1275 - 8 %U http://dx.doi.org/10.1016/0038-1101(94)00263-F %V 38 %X What is needed to provide a design tool for CCHBTs with nominally-undoped collector layers is an analytical model which explicitly relates both the collector current and the breakdown voltage to the thickness of the narrow bandgap material. In this paper, we make the first step in this direction by adapting an existing analytical model for HBTs to enable the computation of the collector current in CCHBTs. At this stage of development we have not incorporated impact ionization into the model. The results of the model are compared with Gummel plots for n-InP/p-InGaAs HBTs fabricated with either a n--InGaAsln/n--InP composite collector, or a single-material n--InGaAs collector %Z composite-collector HBTs;collector current;breakdown voltage;bandgap material;Gummel plots;n-InP/p-InGaAs;n--InGaAsln/n--InP;n--InGaAs;InP-InGaAs; %9 article