A semiconductor device includes a substrate and an oxide semiconductor TFT supported by the substrate. The oxide semiconductor TFT includes an oxide semiconductor layer containing In, Ga, and Zn, a gate electrode, a gate insulating layer formed between the gate electrode and the oxide semiconductor layer, and a source electrode and a drain electrode that are in contact with the oxide semiconductor layer. The oxide semiconductor layer has a layered structure that includes a first layer, a second layer, and an intermediate transition layer disposed between the first layer and the second layer, and the first layer is disposed closer to the gate insulating layer side than the second layer. The first layer and the second layer have different compositions, and the intermediate transition layer has a continuously changing composition from the first layer side toward the second layer side.

A semiconductor device includes an extremely thin semiconductor-on-insulator substrate (ETSOI) having a base substrate, a thin semiconductor layer and a buried dielectric therebetween. A device channel is formed in the thin semiconductor layer. Source and drain regions are formed at opposing positions relative to the device channel. The source and drain regions include an n-type material deposited on the buried dielectric within a thickness of the thin semiconductor layer. A gate structure is formed over the device channel.

Various embodiments of the present application are directed towards a method for forming a semiconductor-on-insulator (SOI) substrate comprising a trap-rich layer with small grain sizes, as well as the resulting SOI substrate. In some embodiments, an amorphous silicon layer is deposited on a high-resistivity substrate. A rapid thermal anneal (RTA) is performed to crystallize the amorphous silicon layer into a trap-rich layer of polysilicon in which a majority of grains are equiaxed. An insulating layer is formed over the trap-rich layer. A device layer is formed over the insulating layer and comprises a semiconductor material. Equiaxed grains are smaller than other grains (e.g., columnar grains). Since a majority of grains in the trap-rich layer are equiaxed, the trap-rich layer has a high grain boundary area and a high density of carrier traps. The high density of carrier traps may, for example, reduce the effects of parasitic surface conduction (PSC).

FDSOI device fabrication method is disclosed. The method comprises: disposing a buried oxide layer on the silicon substrate; disposing a SiGe channel on the buried oxide layer, disposing a nitrogen passivation layer on the SiGe channel layer; disposing a metal gate on the nitrogen passivation layer, and attaching sidewalls to sides of the metal gate; and disposing source and drain regions on the nitrogen passivation layer at both sides of the metal gate, wherein the source and drain regions are built in a raised SiGe layer. The stack structure of the SiGe layer and the nitrogen passivation layer forms the gate channel. This stack structure avoids the low stress of the silicon channel in the conventional device. In addition, it prevents the Ge diffusion from the SiGe channel to the gate dielectric in the conventional device. Thereby the invention improves reliability and performance of the device.

Group III-N transistors of complementary conductivity type employing two polarization junctions of complementary type. Each III-N polarization junction may include two III-N material layers having opposite crystal polarities. The opposing polarities may induce a two-dimensional charge sheet within each of the two III-N material layers. Opposing crystal polarities may be induced through introduction of an intervening layer between two III-N material layers. A III-N heterostructure may include two III-N polarization junctions. A 2D electron gas (2DEG) is induced at a first polarization junction and a 2D hole gas (2DHG) is induced at the second polarization junction. Transistors of complementary type may utilize a separate one of the polarization junctions, enabling III-N transistors to implement CMOS circuitry.

An embodiment is a semiconductor device which includes a first oxide semiconductor layer over a substrate having an insulating surface and including a crystalline region formed by growth from a surface of the first oxide semiconductor layer toward an inside; a second oxide semiconductor layer over the first oxide semiconductor layer; a source electrode layer and a drain electrode layer which are in contact with the second oxide semiconductor layer; a gate insulating layer covering the second oxide semiconductor layer, the source electrode layer, and the drain electrode layer; and a gate electrode layer over the gate insulating layer and in a region overlapping with the second oxide semiconductor layer. The second oxide semiconductor layer is a layer including a crystal formed by growth from the crystalline region.

A semiconductor device includes an extremely thin semiconductor-on-insulator substrate (ETSOI) having a base substrate, a thin semiconductor layer and a buried dielectric therebetween. A device channel is formed in the thin semiconductor layer. Source and drain regions are formed at opposing positions relative to the device channel. The source and drain regions include an n-type material deposited on the buried dielectric within a thickness of the thin semiconductor layer. A gate structure is formed over the device channel.

An embodiment is a semiconductor device which includes a first oxide semiconductor layer over a substrate having an insulating surface and including a crystalline region formed by growth from a surface of the first oxide semiconductor layer toward an inside; a second oxide semiconductor layer over the first oxide semiconductor layer; a source electrode layer and a drain electrode layer which are in contact with the second oxide semiconductor layer; a gate insulating layer covering the second oxide semiconductor layer, the source electrode layer, and the drain electrode layer; and a gate electrode layer over the gate insulating layer and in a region overlapping with the second oxide semiconductor layer. The second oxide semiconductor layer is a layer including a crystal formed by growth from the crystalline region.

Various embodiments of the present application are directed towards a method for forming a semiconductor-on-insulator (SOI) substrate comprising a trap-rich layer with small grain sizes, as well as the resulting SOI substrate. In some embodiments, an amorphous silicon layer is deposited on a high-resistivity substrate. A rapid thermal anneal (RTA) is performed to crystallize the amorphous silicon layer into a trap-rich layer of polysilicon in which a majority of grains are equiaxed. An insulating layer is formed over the trap-rich layer. A device layer is formed over the insulating layer and comprises a semiconductor material. Equiaxed grains are smaller than other grains (e.g., columnar grains). Since a majority of grains in the trap-rich layer are equiaxed, the trap-rich layer has a high grain boundary area and a high density of carrier traps. The high density of carrier traps may, for example, reduce the effects of parasitic surface conduction (PSC).

The silicon carbide semiconductor device includes: a silicon carbide layer; a silicon dioxide layer provided above the silicon carbide layer and containing nitrogen; and a transition region arranged between the silicon carbide layer and the silicon dioxide layer, and containing carbon, oxygen, and nitrogen, wherein the maximum nitrogen concentration in the transition region is 1.010.sup.20 cm.sup.3 or higher. The maximum nitrogen concentration in the transition region is five or more times higher than the maximum nitrogen concentration in the silicon dioxide layer.