Thermal stability of Ti∕Pt∕Cu Schottky contact on InAlAs layer

Electrical characteristics and thermal stability of the Ti∕Pt∕Cu Schottky contact on InAlAs were investigated. The Ti∕Pt∕Cu Schottky contact had comparable electrical properties compared to the conventional Ti∕Pt∕Au contact after annealing. As judged from the material analysis, the Ti∕Pt∕Cu on InAlAs after 350°C annealing showed no diffusion sign into the InAlAs. After 400°C annealing, the interfacial mixing of Cu and the underlying layers occurred and resulted in the formation of Cu4Ti. The results show that Ti∕Pt∕Cu Schottky contact using platinum as the diffusion barrier is very stable up to 350°C annealing and can be used for InAlAs∕InGaAs high-electron mobility transistors and monolithic microwave integrated circuits.