Abstract
Atomic-layer-deposited Al2O3 on In0.53Ga0.47As with short air-exposure between the oxide and semiconductor deposition without any InGaAs surface treatments has shown negligible frequency-dispersion capacitance-voltage (CV) characteristics in the depletion and accumulation region, and well-behaved frequency-dependent inversion curves. The interfacial density of states (Dit) of the metal-oxide-semiconductor capacitor (MOSCAP) was determined by the Terman method and the conductance method. The Dit distribute over the bandgap of In0.53Ga047As in “U”-shape giving lower Dit values near the mid-gap were obtained about 5×1011-3×1012 eV-1cm-2. By the conductance method, however, the Dit values were adopted as the authentic values and the Dit close to the mid-gap is about 3×1012 eV-1cm-2. The quasi-static CV characteristics indicate a high efficiency of 63% for the Fermi-level movement efficiency near the mid-gap.On the basis of the high quality Al2O3/InGaAs interface, self-aligned enhancement-mode (E-mode) inversion-channel InxGa1-xAs (x=0.53 and 0.75) n-MOSFETs using atomic-layer-deposited Al2O3 as the gate dielectric have been demonstrated. Devices with lower dopant activation temperature (DAT) and higher indium content channel show better output DC characteristics. A low subthreshold swing ~ 103 mV/dec was obtained from the In0.75Ga0.25As MOSFETs with DAT of 600oC; furthermore, a maximum drain current (IDS) ~ 1.1 mA/μm was measured at a drain-to-source voltage of 1 V from a 350-nm gate-length device, the highest value among all enhancement-mode inversion-channel n-MOSFETs using InGaAs as the channels and ex-situ grown high-□ dielectrics. In addition, device optimization including TiN gate metal etching by ICP-RIE, channel doping, S/D implantation, and channel engineering were also studied in this work.