Effect of Schottky barrier alteration on the low-frequency noise of InP-based HEMTs

For the first time the effect of increasing the Schottky barrier´s Al content of InP-based InAlAs-InGaAs HEMTs from 48 to 60% on the low-frequency (LF) drain and gate current noise is investigated. It is shown that the LF gate current noise S/sub IG/(f) for the 60% case decreases by almost three decades, while the LF drain current noise S/sub IDS/(f) stays at the same level. From small coherence values, it can be concluded that drain and gate noise sources can be treated separately which facilitates the LF noise modeling of these HEMTs.