Challenges to III-V Epi Growth for Increased Performance and Functionality Required in Advanced Wireless Devices

Abstract

InGaP/GaAs HBTs have been achieved via base doping and base compositional grades focused adjacent to the collector. This has been done while avoiding unacceptable increases in base sheet resistances which are typically seen with plain linear grades. Additionally, semi-ballistic launching of carriers into the base layer is shown to further enhance base electron velocity and device gain. These base grading and launching techniques enable enhanced dc gain which, among other benefits, can offset the gain killing effects of very heavily doped contact layers for advanced wireless devices.