Thermal Stability Performance of Metamorphic High Electron Mobility Transistors (MHEMTs)

The thermal stability performance of double delta-doped In_0.42Al_0.58As/In_0.46Ga_0.54As 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 (Au). 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 (1.63times10^-3 muA/mmldrK), output conductance (1.23 muS/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.