The present disclosure provides a semiconductor structure and a forming method thereof. The semiconductor structure includes: a substrate and an epitaxial layer disposed on the substrate. At least a part of the epitaxial layer is doped with metal atoms, and the doping concentration of the metal atoms at the bottom surface of the epitaxial layer near the substrate is larger than 110.sup.17 atoms/cm.sup.3.

The present disclosure provides a semiconductor structure and a forming method thereof. The semiconductor structure includes: a substrate and an epitaxial layer disposed on the substrate. At least a part of the epitaxial layer is doped with metal atoms, and the doping concentration of the metal atoms at the bottom surface of the epitaxial layer near the substrate is larger than 110.sup.17 atoms/cm.sup.3.

Example embodiments relate to a field-effect transistors having improved layouts. One example field-effect transistor includes a semiconductor substrate on which at least one transistor cell array is arranged. Each transistor cell includes a first transistor cell unit. Each first transistor cell unit includes a plurality of gate fingers, a main gate finger segment, a plurality of drain fingers, and a main drain finger segment. Each first transistor cell unit also includes a main gate finger base connected to the main gate finger segment of the first transistor cell unit and extending from that main gate finger segment towards the main drain finger segment of that first transistor cell unit. Further, each first transistor cell unit includes a main drain finger base connected to the main drain finger segment of that first transistor cell and extending from that main drain finger segment towards that main gate finger segment.

Example embodiments relate to a field-effect transistors having improved layouts. One example field-effect transistor includes a semiconductor substrate on which at least one transistor cell array is arranged. Each transistor cell includes a first transistor cell unit. Each first transistor cell unit includes a plurality of gate fingers, a main gate finger segment, a plurality of drain fingers, and a main drain finger segment. Each first transistor cell unit also includes a main gate finger base connected to the main gate finger segment of the first transistor cell unit and extending from that main gate finger segment towards the main drain finger segment of that first transistor cell unit. Further, each first transistor cell unit includes a main drain finger base connected to the main drain finger segment of that first transistor cell and extending from that main drain finger segment towards that main gate finger segment.

A method for manufacturing an ohmic contact for a HEMT device, comprising the steps of: forming a photoresist layer, on a semiconductor body comprising a heterostructure; forming, in the photoresist layer, an opening, through which a surface region of the semiconductor body is exposed at said heterostructure; etching the surface region of the semiconductor body using the photoresist layer as etching mask to form a trench in the heterostructure; depositing one or more metal layers in said trench and on the photoresist layer; and carrying out a process of lift-off of the photoresist layer.

An HEMT device, comprising: a semiconductor body including a heterojunction structure; a dielectric layer on the semiconductor body; a gate electrode; a drain electrode, facing a first side of the gate electrode; and a source electrode, facing a second side opposite to the first side of the gate electrode; an auxiliary channel layer, which extends over the heterojunction structure between the gate electrode and the drain electrode, in electrical contact with the drain electrode and at a distance from the gate electrode, and forming an additional conductive path for charge carriers that flow between the source electrode and the drain electrode.

A High electron mobility transistor (HEMT) includes a source electrode, a gate electrode, a drain electrode, a channel forming layer in which a two-dimensional electron gas (2DEG) channel is induced, and a channel supplying layer for inducing the 2DEG channel in the channel forming layer. The source electrode and the drain electrode are located on the channel supplying layer. A channel increase layer is between the channel supplying layer and the source and drain electrodes. A thickness of the channel supplying layer is less than about 15 nm.

A device includes a substrate and insulation regions over a portion of the substrate. A first semiconductor region is between the insulation regions and having a first conduction band. A second semiconductor region is over and adjoining the first semiconductor region, wherein the second semiconductor region includes an upper portion higher than top surfaces of the insulation regions to form a semiconductor fin. The second semiconductor region also includes a wide portion and a narrow portion over the wide portion, wherein the narrow portion is narrower than the wide portion. The semiconductor fin has a tensile strain and has a second conduction band lower than the first conduction band. A third semiconductor region is over and adjoining a top surface and sidewalls of the semiconductor fin, wherein the third semiconductor region has a third conduction band higher than the second conduction band.

A field-effect transistor (a GaN-based HFET) includes a gate electrode, a gate electrode pad, a first wiring line connecting one end of the gate electrode and the gate electrode pad, a second wiring line connecting the other end of the gate electrode and the gate electrode pad, and a resistance element that is connected to the first wiring line and is capable of adjusting the impedance of the first wiring line.

A method to transfer a layer of graphene from one substrate to another substrate is provided. The method includes providing a first layered structure including, from bottom to top, a copper foil, a layer of graphene, an adhesive layer and a carrier substrate. The copper foil is removed exposing a surface of the layer of graphene. Next, an oxide bonding enhancement dielectric layer is formed on the exposed surface of the layer of graphene. A second layered structure including a receiver substrate and a dielectric oxide layer is provided. Next, an exposed surface of the dielectric oxide layer is bonded to an exposed surface of the oxide bonding enhancement dielectric layer. The carrier substrate and the adhesive layer are removed exposing the layer of graphene.