Cryogenic Ultra-Low Noise InP High Electron Mobility Transistors

Indium phosphide high electron mobility transistors (InP HEMTs), are today the best transistors for cryogenic low noise amplifiers at microwave frequencies. Record noise temperatures below 2 K using InP HEMT equipped cryogenic low noise amplifiers (LNAs) were demonstrated already a decade ago. Since then, reported progress in further reducing noise has been slow. This thesis presents new technology optimization, modeling, measurements and circuit implementation for the cryogenic InP HEMT. The findings have been used to demonstrate a new record minimum noise temperature of 1 K at 6 GHz. The thesis considers aspects all the way from material, process and device design, to hybrid and monolithic microwave integrated circuit (MMIC) LNAs. The epitaxial structure has been developed for lower access resistance and improved transport characteristics. By investigating device passivation, metallization, gate recess etch, and circuit integration, low-noise InP HEMT performance was optimized for cryogenic operation