Suppression of GeO x interfacial layer and enhancement of the electrical performance of the high-K gate stack by the atomic-layer-deposited AlN buffer layer on Ge metal-oxide-semiconductor devices.

For high-performance nanoscale Ge-based transistors, one important point of focus is interfacial germanium oxide (GeO x ), which is thermodynamically unstable and easily desorbed. In this study, an atomic-layer-deposited AlN buffer layer was introduced between the crystalline ZrO2 high-K gate dielectrics and epitaxial Ge, in order to reduce the formation of interfacial GeO x . The results of X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy demonstrate that the AlN buffer layer suppressed the formation of interfacial GeO x . Hence, significant enhancement of the electrical characteristics of Ge metal-oxide-semiconductor (MOS) capacitors was achieved with a two-orders-of-magnitude reduction in the gate leakage current, a 34% enhancement of the MOS capacitance, and a lower interfacial state density. The results indicate that the AlN buffer layer is effective in providing a high-quality interface to improve the electrical performance of advanced Ge MOS devices.

Room-temperature field effect transistors with metallic ultrathin TiN-based channel prepared by atomic layer delta doping and deposition.

Metallic channel transistors have been proposed as the candidate for sub-10 nm technology node. However, the conductivity modulation in metallic channels can only be observed at low temperatures usually below 100 K. In this study, room-temperature field effect and modulation of the channel resistance was achieved in the metallic channel transistors, in which the oxygen-doped TiN ultrathin-body channels were prepared by the atomic layer delta doping and deposition (AL3D) with precise control of the channel thickness and electron concentration. The decrease of channel thickness leads to the reduction in electron concentration and the blue shift of absorption spectrum, which can be explained by the onset of quantum confinement effect. The increase of oxygen incorporation results in the increase of interband gap energy, also giving rise to the decrease in electron concentration and the blue shift of absorption spectrum. Because of the significant decrease in electron concentration, the screening effect was greatly suppressed in the metallic channel. Therefore, the channel modulation by the gate electric field was achieved at room temperature due to the quantum confinement and suppressed screening effect with the thickness down to 4.8 nm and the oxygen content up to 35% in the oxygen-doped TiN ultrathin-body channel.