Reliability of AlInAs/InGaAs/InP HEMT with WSi ohmic contacts

We have obtained extremely high reliability on the AlInAs/InGaAs/InP HEMT using WSi ohmic electrodes. The WSi electrode of this device demonstrates high stability under a high temperature (Ta=170/spl sim/200/spl deg/C) operating life test. The sample analyzed by a cross-sectional TEM/EDX shows no degradation of the WSi/InGaAs interface, on the other hand, titanium (Ti) and fluorine (F) are detected in the AlInAs layer. The estimated degradation mechanism of this device is related with decrease of carrier concentration in the epitaxial layer.