Comprehensive Study of Thermal Stability Performance of Metamorphic Heterostructure Field-Effect Transistors with Ti/Au and Au Metal Gates.

The thermal stability performance of double δ-doped In_0.42Al_0.58As/In_0.46Ga_0.54As metamorphic heterostructure field-effect 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 tum-on voltage (–2.19 mV/K), breakdown voltage (–34 mV/K), logic swing (–1.24 mV/K), transition region width (0.05 mV/K), on-off current ratio (–3.55/K), threshold voltage (–0.25 mV/K), impact ionization-induced gate current (1.63 × 10^-3 μA/mm K), output conductance (1.23 μS/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 digital and switching circuit applications. [ABSTRACT FROM AUTHOR]