Highly p-typed superlattices consist of undoped InAs and carbon-doped GaAs layers

The strained-layer-superlattice (SLS) consisting of undoped InAs and carbon-doped GaAs (GaAs:C) layers were successfully grown on InP substrates by LP-MOVPE. The grown superlattice shows the p-type conductivity with a hole concentration of 1×1019cm−3 and Hall mobility of 70cm2V−1s−1 at room temperature. The resistivity is low enough to be used as an electrically equivalent highly p-type InGaAs base layer of an InP/InGaAs heterojunction bipolar transistor (HBT). The High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF STEM) images reveal that the InAs/GaAs:C superlattice has an interface more abrupt than the undoped InAs/GaAs superlattice. It is attributed to the suppressed In diffusion from InAs to GaAs due to carbon doping in GaAs. ► The superlattice consisting of undoped InAs and GaAs:C layers was grown by MOVPE. ► This is electrically equivalent to highly p-type InGaAs. ► This possesses higher crystallinity than that of the undoped InAs/GaAs superlattice. ► This superlattice can be used as a p-type base layer of an InP/InGaAs HBT.