A gate electrode includes a main portion formed of a gate electrode material, and a gate electrode barrier layer disposed between the main portion and a barrier layer and formed of a conductive material that prevents the gate electrode material from diffusing into the barrier layer. A surface of the main portion in a region above a first insulating layer faces a periphery without a layer of the conductive material being formed.

A bonded semiconductor device including an epitaxial layer, and a support substrate made of a material different from that of the epitaxial layer and bonded to the epitaxial layer. Any one of the epitaxial layer and the support substrate has a bonding surface with a radial pattern including recesses or protrusions radially spreading from a certain point on the bonding surface as a center.

A field effect transistor comprising: a first semiconductor structure, the first semiconductor structure having a channel layer; a second semiconductor structure, the second semiconductor structure is arranged on the first semiconductor structure, and the second semiconductor structure is stacked in sequence from bottom to top with a Schottky layer, a first etch stop layer, a wide recess layer, an ohmic contact layer, and a narrow recess, a wide recess is opened in the ohmic contact layer, so that the upper surface of the wide recess layer forms a wide recess area and the upper surface of the Schottky layer forms a narrow recess area; at least one delta-doped layer, a gate metal contact, the gate metal contact is formed inside the wide recess a source metal contact; and a drain metal contact, and the drain metal contact is located on the other side of the gate metal contact.

A method for controlling a concentration of donors in an Al-alloyed gallium oxide crystal structure includes implanting a Group IV element as a donor impurity into the crystal structure with an ion implantation process and annealing the implanted crystal structure to activate the Group IV element to form an electrically conductive region. The method may further include depositing one or more electrically conductive materials on at least a portion of the implanted crystal structure to form an ohmic contact. Examples of semiconductor devices are also disclosed and include a layer of an Al-alloyed gallium oxide crystal structure, at least one region including the crystal structure implanted with a Group IV element as a donor impurity with an ion implantation process and annealed to activate the Group IV element, an ohmic contact including one or more electrically conductive materials deposited on the at least one region.

A semiconductor device (field effect transistor) includes a gate insulating layer between both of a bottom part and a lateral surface of a recess part and a penetration portion of a gate electrode. The gate insulating layer is composed of an oxide of a substance which a barrier layer is composed of For example, the gate insulating layer is composed of a layer of In oxide and a layer of Al oxide.

A method for forming a III-V construction over a group IV substrate comprises providing an assembly comprising the group IV substrate and a dielectric thereon. The dielectric layer comprises a trench exposing the group IV substrate. The method further comprises initiating growth of a first III-V structure in the trench, continuing growth out of the trench on top of the bottom part, growing epitaxially a sacrificial second III-V structure on the top part of the first III-V structure, and growing epitaxially a third III-V structure on the sacrificial second III-V structure. The third III-V structure comprises a top III-V layer. The method further comprises physically disconnecting a first part of the top layer from a second part thereof, and contacting the sacrificial second III-V structure with the liquid etching medium.

A semiconductor device includes a semiconductor stacked structure including at least an electron transit layer and an electron supply layer over a substrate. The electron supply layer includes a first portion and second portions sandwiching the first portion, and the first portion has a higher energy of a conduction band than that of the second portion, and includes a doped portion doped with an n-type impurity and undoped portions that sandwich the doped portion and are not doped with an impurity.

A crystalline base substrate including a first semiconductor material and having a main surface is provided. The base substrate is processed so as to damage a lattice structure of the base substrate in a first region that extends to the main surface without damaging a lattice structure of the base substrate in second regions that are adjacent to the first region. A first semiconductor layer of a second semiconductor material is formed on a portion of the main surface that includes the first and second regions. A third region of the first semiconductor layer covers the first region of the base substrate, and a fourth region of the first semiconductor layer covers the second region of the base substrate. The third region has a crystalline structure that is disorganized relative to a crystalline structure of the fourth region. The first and second semiconductor materials have different coefficients of thermal expansion.

A semiconductor device includes: a channel layer made of a compound semiconductor; a barrier layer provided above the channel layer and made of a compound semiconductor in which an energy band on a carrier travel side in a junction with respect to the channel layer is farther from an intrinsic Fermi level in the channel layer than in the channel layer; a low-resistance region provided in a surface layer of the barrier layer, in which resistance is kept lower than portions around by containing impurity; a source electrode and a drain electrode connected to the barrier layer at positions sandwiching the low-resistance region; a gate insulating layer provided on the low-resistance region; and a gate electrode provided above the low-resistance region through the gate insulating layer.

A semiconductor structure comprises a semiconductive substrate comprising a top surface, a III-V compound layer over the semiconductive substrate, and a first passivation layer over the III-V compound layer. The semiconductor structure also includes an etch stop layer over the first passivation layer. The semiconductor structure further includes a gate stack over the first passivation layer and surrounded by the etch stop layer.