Semiconductor devices and fabrication methods thereof are described. For example, a semiconductor device includes a semiconductor layer, a source region disposed in the semiconductor layer, a drain region disposed in the semiconductor layer, a gate electrode, and an insulating layer disposed between a portion of the gate electrode and the semiconductor layer. The insulating layer has a first sidewall extending toward the source region and a second sidewall extending toward the drain region, the first sidewall having a first slope and the second sidewall having a second slope greater than the first slope.

A display device and method of fabricating the same are provided. The display device includes a substrate and a thin-film transistor formed on the substrate. The thin-film transistor includes a lower gate conductive layer disposed on the substrate, and a lower gate insulating film disposed on the lower gate conductive layer The lower gate insulating film includes an upper surface and sidewalls. The thin-film transistor includes an active layer disposed on the upper surface of the lower gate insulating film, the active layer including sidewalls. At least one of the sidewalls of the lower gate insulating film and at least one of the sidewalls of the active layer are aligned with each other.

Provided are semiconductor devices, e.g., transistors, and methods of manufacturing semiconductor devices which achieve NMOS band edge with low resistivity and having improved device performance and reliability. Provided are materials that can be used as effective N-metal films for transistors. Instead of conventional titanium aluminum carbide (TiAlC) based N-metal films, provided are binary/ternary metal carbide films and metal silicide films that may be used as N-metal films with no/minimal high-k (HK) capping layer required.

A field-effect transistor (FET) device having a modulated threshold voltage (Vt) includes a source electrode, a drain electrode, a channel region extending between the source electrode and the drain electrode, and a gate stack on the channel region. The gate stack includes an ultrathin dielectric dipole layer configured to shift the modulated Vt in a first direction, a high-k (HK) insulating layer on the ultrathin dielectric dipole layer, and a gate metal layer on the HK insulating layer configured to shift the modulated Vt in a second direction.