Thermal resistance characterization of implanted subcollector InP-based HBTs

We present the results. of measurements of thermal resistivity of the heterojunction bipolar transistor (HBT) devices, utilizing selective ion implantation to define the subcollector. This new device fabrication technique resulted in high-speed HBT devices with substantially reduced thermal resistivity, compared to devices utilizing. the conventional fabrication approach which includes mesa isolation for pattern definition. The measurements were taken on-full-thickness 3" InP wafers at T-amb from 30 degreesC to 180 degreesC and two separate emitter current densities. We present data on three device epitaxial structures, with identical device layouts and discuss the relationship of V-be to temperature,at these elevated power and temperature levels.