In this work, we successfully demonstrated In_0.53Ga_0.47As/InAs/In_0.53Ga_0.47As composite channel metamorphic high electron mobility transistors (mHEMTs) on a GaAs substrate. The fabricated mHEMTs with a 100 nm gate length exhibited excellent DC and logic characteristics such as V_T = −0.13 V, g_m,max = 949 mS/mm, subthreshold swing (SS) = 84 mV/dec, drain-induced barrier lowering (DIBL) = 89 mV/V, and I_on/I_off ratio = 9.8 × 10³ at a drain-source voltage (V_DS) = 0.5 V. In addition, the device exhibited excellent high-frequency characteristics, such as f_T/f_max = 261/304 GHz for the measured result and well-matched modeled f_T/f_max = 258/309 GHz at V_DS = 0.5 V, which is less power consumption compared to other material systems. These high-frequency characteristics are a well-balanced demonstration of f_T and f_max in the mHEMT structure on a GaAs substrate.

We electrically detect charge current induced spin polarization on the surface of a molecular beam epitaxy grown Bi₂Te₃ thin film in a two-terminal device with a ferromagnetic MgO/Fe contact and a nonmagnetic Ti/Au contact. The two-point resistance, measured in an applied magnetic field, shows a hysteresis tracking the magnetization of Fe. A theoretical estimate is obtained for the change in resistance on reversing the magnetization direction of Fe from coupled spin-charge transport equations based on the quantum kinetic theory. The order of magnitude and the sign of the hysteresis are consistent with the spin-polarized surface state of Bi₂Te₃.

In this paper, we investigated the effect of in-situ Ar ion plasma surface pre-treatment in order to improve the interface properties of In_0.53Ga_0.47As for high-κ top-gate oxide deposition. X-ray photoelectron spectroscopy (XPS) and metal-oxide-semiconductor capacitors (MOSCAPs) demonstrate that Ar ion treatment removes the native oxide on In_0.53Ga_0.47As. The XPS spectra of Ar treated In_0.53Ga_0.47As show a decrease in the AsO_x and GaO_x signal intensities, and the MOSCAPs show higher accumulation capacitance (C_acc), along with reduced frequency dispersion. In addition, Ar treatment is found to suppress the interface trap density (D_it), which thereby led to a reduction in the threshold voltage (V_th) degradation during constant voltage stress and relaxation. These results outline the potential of surface treatment for III-V channel metal-oxide-semiconductor devices and application to non-planar device process.