MOMBE growth of InGaP with tertiarybutylphosphine (TBP) and its application to the carbon-doped base InGaP/GaAs HBTs

Abstract

Tertiarybutylphosphine (TBP), which is a promising substitute for phosphine (PH/sub 3/), was used for the growth of In/sub 0.5/Ga/sub 0.5/P by metalorganic molecular beam epitaxy (MOMBE) with elemental In and Ga as group III sources. In the decomposition of TBP, the catalysis by heated Ta is important to obtain high quality In/sub 0.5/Ga/sub 0.5/P layers as compared with the case of only pyrolysis. We modified the cracking cell for TBP to the new one by including Ta sheet and shots inside the PBN crucible, and undoped In/sub 0.5/Ga/sub 0.5/P with n-type background carrier concentrations of /spl sim/4/spl times/10/sup 15/ cm/sup -3/ was obtained. Electron concentrations ranging from 10/sup 17/ to 10/sup 19/ cm/sup -3/ were successfully controlled by using cracked Si/sub 2/H/sub 6/ as n-type dopant source. The MOMBE growth of In/sub 0.5/Ga/sub 0.5/P layers was applied to carbon (C)-doped base In/sub 0.5/Ga/sub 0.5/P/GaAs heterojunction bipolar transistors (HBTs) with high hole concentrations in the base. Common emitter current gain (h/sub fe/) of 28 at J/sub c/=1.1 kA/cm/sup 2/ was obtained for HBTs with the hole concentration in the C-doped GaAs base of 1/spl times/10/sup 20/ cm/sup -3/. >