On the profile design of SiGe HBTs for RF lunar applications down to 43 K

New germanium and boron base profiles are designed and tested for emerging lunar RF applications down to 43 K using SiGe HBTs. Device optimization in 1^st generation SiGe HBTs to minimize the carrier freezeout and to suppress the heterojunction barrier effects without changing basic fabrication processes was attempted. Optimizing the device enhances f_T by 20% and f_max by 70% as compared to a standard HBT, at 43 K. A comprehensive dc and ac investigation from 43 K to 300 K was conducted to demonstrate the capabilities of these newly optimized SiGe HBTs for emerging lunar RF electronics.