Low tensile strain GaInAs : uid/GaAs : C superlattice heterostructures grown by LP MOCVD: application to GaInP/GaAs heterojunction bipolar transistorbase layer

This paper reports on the investigation of GaInP/GaAs HBT-advanced structur es with well-controlled strained base layers based on GaAs:C/GaInAs:uid sup erlattice heterostructures. High-resolution X-ray diffraction (HRXRD) and T EM experiments performed on test GaAs:C/GaInAs:uid superlattice heterostruc tures reveal well defined and sharp GaInAs/GaAs well/barrier interfaces wit h a high structural quality. C-V measurements and SIMS analysis, indicate t hat a low base sheet resistance is achieved with less carbon concentration than needed in the commonly HBTs C-doped GaAs base layers, together with a large strain reduction as shown by X-ray. HBT test structures consisting of 8-11 (GaAs:C/GaInAs:uid) period superlattice base layers, with GaInAs thic kness varying from 0.5 to 3.4 nm have been processed. It is demonstrated th at the GaInAs layer thickness must be less than 1 nm to preserve the curren t gain beta of the device. (C) 2000 Elsevier Science B.V. All rights reserv ed.