Parasitic effects and long term stability of InP-based HEMTs

A study of InP based HEMTs implemented with different process options will be reported. It will be demonstrated that devices with an InP etch stopper layer or with a narrow lateral gate recess region do not present any kink effect, neither any transconductance frequency dispersion, g(m)(f) and a stable behavior with respect to hot electron aging is observed. The opposite occurs in devices without the InP etch stopper layer and a wide lateral gate recess region. The data presented confirm the effectiveness of an InP passivating layer in improving the reliability of advanced InP-HEMTs, and point out at the free InAlAs surface as responsible for the observed instabilities (kink effects, g(m)(f) dispersion).