Reliability analysis of InP-based HBTs

The reliability of InP-based heterojunction bipolar transistors (HBTs) with AuGe/Ni alloyed ohmic electrodes, which are widely used for n-type ohmic contacts, was investigated. Scanning electron microscopy (SEM) has revealed that the failure mechanism of InP-based HBTs is the diffusion of alloyed electrodes into the GaInAs layer. The activation energy was 0.50 eV. We examined non-alloyed electrodes (Pt/Ti/Pt/Au) for n-type ohmic contacts to improve the reliability of InP-based HBTs. By transmission electron microscopy (TEM) and x-ray diffraction (XRD), the existence of an indium-platinum (In-Pt) layer was observed at the interface between the electrodes and the epitaxial layer. The diffusion was suppressed by this layer and InP-based HBTs with non-alloyed electrodes exhibited stable characteristics under temperature stress