Thermal stability performance of metamorphic high electron mobility transistors (MHEMTs)

The thermal stability performance of double delta-doped In0.4Al0.58As/In0.46Ga0.54As metamorphic high electron mobility transistors with Au and Ti/Au metal gates are comprehensively studied and demonstrated. By evaporating the Ti/Au metal gate, the thermal stability of device characteristics are significantly improved as compared with the device with conventional metal gate (An). Experimentally, the device with a Ti/Au metal gate simultaneously exhibits the considerably lower temperature degradation in turn-on voltage (-2.19 mV/K), breakdown voltage (-34 mV/K), impact ionization-induced gate current (1.63x10(-3) mu A/mm center dot K), output conductance (1.23 mu S/mm K), and voltage gain (-0.33 /K) as the temperature is increased from 300 to 510 K. Consequently, the studied device with a Ti/Au metal gate is a good candidate for high-speed and high-temperature applications.