Pd-Ge based Ohmic Contacts to InGaAs-InAlAs High Electron Mobility Transistors

This paper reports on the use of Pd-Ge-Ag Au for ohmic contacts to InAlAs/InGaAs High Electron Mobility Transistors (HEMTs). After annealing onto a hot plate, specific contact resistance of 1 10^-6Ωcm² and 5 10^-7 Ωcm² for structures having respectively a 5 nm undoped and a 50 nm n+ doped InGaAs cap layer were obtained in a wide temperature range (380°C470°C). No thermal degradation was observed after 100 hours @ 325°C and 24 hours @ 420°C.