High-temperature electron transport in metamorphic InGaAs/InAlAs heterostructures

We have investigated high-temperature electron transport in metamorphic InGaAs/InAlAs modulation-doped heterostructures with several indium contents. The electron mobility characterizing the low-field transport properties was obtained from the Hall measurements. From room temperature to 400 K, ∼26% decrease in the mobility was observed, which is well-explained by the polar-optical-phonon scattering theory. The indium content dependence of the mobility is explained by the theory with the Γ-valley electron mass. On the other hand, the electron saturation velocity characterizing the high-field transport properties was studied by means of the delay-time analysis of the transistors with gate length of 0.12-1.0 μm. We observed ∼12% decrease in the saturation velocity from room temperature to 400 K, which is smaller than that in the mobility and roughly consistent with the energy relaxation theory. In the indium content dependence of the saturation velocity, the effect of decrease in the electron density in the L- and X-valley is important. The high-frequency performance of the transistors at high temperatures shows a deterioration according to the decrease in the saturation velocity.