Silicon-Germanium as an Enabling Technology for Extreme Environment Electronics

“Extreme environment” electronics represent an important niche market in the trillion dollar global electronics industry and span the operation of electronic circuits and systems in surroundings lying outside the domain of conventional commercial or military specifications. Such extreme environments might include, for instance, the following: 1) operation down to very low temperatures (e.g., to 77 K or even 4.2 K or below); 2) operation up to very high temperatures (e.g., to 200°C or even 300°C); 3) operation across very wide and/or cyclic temperature swings (e.g., -230°C +120°C night to day, as found on the lunar surface); 4) operation in a radiation environment (e.g., in space while orbiting the Earth); or 5) at worst case even with all four simultaneously. The unique bandgap-engineered features of silicon-germanium (SiGe) heterojunction bipolar transistors and the electronic circuits built from them offer a considerable potential for simultaneously coping with all four of these extreme environments, potentially with no process modifications, ultimately providing compelling advantages at the integrated circuit and system level across a wide class of envisioned commercial and defense applications. Here, we detail the nuances associated with using SiGe technology for extreme environment electronics, paying particular attention to recent developments in the field.