A transistor comprises a semiconductor substrate and a barrier metal layer forming a Schottky barrier. One or more insulated gates may be positioned adjacent to an edge of the Schottky barrier. By applying a reverse bias voltage between the semiconductor substrate and the barrier metal, and applying a gate voltage between the one or more insulated gates and the barrier metal, a reverse bias current may be increased to a reverse bias conducting state. When the gate voltage is sufficient, the transistor may conduct current between the semiconductor substrate and the barrier metal. For example, voltages may be applied to an n-type substrate and an insulated gate (both relative to the barrier metal), and a current may flow from the semiconductor substrate to the barrier metal. The transistor may operate as a switch, a filter, a rectifier, an oscillator, or an amplifier.

A network device includes one or more circuit components. The one or more circuit components include a semiconductor substrate, a first device terminal and a second device terminal, a drift region, and a mobility modulator. Both device terminals are coupled to the semiconductor substrate, the second device terminal being spatially separated from the first device terminal. The drift region is disposed on the semiconductor substrate between the first device terminal and the second device terminal, the drift region being configured to allow a flow of charge-carriers between the first device terminal and the second device terminal. The mobility modulator is coupled to the drift region, the mobility modulator being configured to selectively apply a field across the drift region responsive to one or more modulation signals, so as to modulate a mobility of charge-carriers as a function of longitudinal position along the drift region.

A semiconductor device includes a first active region defined on a substrate, a first gate electrode across the first active region, a first drain region in the first active region at a position adjacent to the first gate electrode, an undercut region between the first active region and the first gate electrode, and a first gate spacer on a side surface of the first gate electrode and extending into the undercut region.

A semiconductor device includes a first active region defined on a substrate, a first gate electrode across the first active region, a first drain region in the first active region at a position adjacent to the first gate electrode, an undercut region between the first active region and the first gate electrode, and a first gate spacer on a side surface of the first gate electrode and extending into the undercut region.

A semiconductor device includes a first active region defined on a substrate, a first gate electrode across the first active region, a first drain region in the first active region at a position adjacent to the first gate electrode, an undercut region between the first active region and the first gate electrode, and a first gate spacer on a side surface of the first gate electrode and extending into the undercut region.

According to one embodiment, a method includes forming a drain contact above a channel, each having a hollow circular cross-section thereof along a plane perpendicular to a film thickness direction, forming gate dielectric layers on sides of the drain contact and the channel, forming a source line positioned below the channel that is electrically coupled to a plurality of channels in a direction along the plane, forming gate layers on sides of the gate dielectric layers, where an inner gate layer fills a hole through a center of a center concentric circular cross-section of the gate dielectric layers along the plane, and where an outer gate layer surrounds an outside concentric circular cross-section of the gate dielectric layers along the plane, forming an electrode above the upper surface of the drain contact, and forming a fourth insulative layer on sides of the electrode along the plane.

According to one embodiment, a method includes forming a drain contact above a channel, each having a hollow circular cross-section thereof along a plane perpendicular to a film thickness direction, forming gate dielectric layers on sides of the drain contact and the channel, forming a source line positioned below the channel that is electrically coupled to a plurality of channels in a direction along the plane, forming gate layers on sides of the gate dielectric layers, where an inner gate layer fills a hole through a center of a center concentric circular cross-section of the gate dielectric layers along the plane, and where an outer gate layer surrounds an outside concentric circular cross-section of the gate dielectric layers along the plane, forming an electrode above the upper surface of the drain contact, and forming a fourth insulative layer on sides of the electrode along the plane.

High electron mobility leads to better device performance and today is achieved by fabricating gated devices within a high-mobility two-dimensional electron gas (2DEG. However, the fabrication techniques used to form these devices lead to rapid degradation of the 2DEG quality which then can limits the mobility of the electronic devices. Accordingly, it would be beneficial to provide a process/technique which circumvents this processing and 2DEG layer damage. By exploiting a flip-chip methodology such damaging processing steps are separated to a second die/wafer which is then coupled to the 2DEG wafer. Extensions of the technique with two or more different semiconductor materials or material systems may be employed in conjunction with one or more electronic circuits to provide 2DEG enabled circuits in 2D and/or 3D stacked configurations. Further semiconductor materials providing EG elements may incorporate one or more of 2DEG, 1DEG, and zero DEG structures.