This thin film transistor comprises, on a substrate, at least a gate electrode, a gate insulating film, an oxide semiconductor layer, a source-drain electrode, and two or more protective films. The oxide semiconductor layer comprises Sn, O and one or more elements selected from the group consisting of In, Ga and Zn. In addition, the two or more protective films are composed of at least a first protective film that is in contact with the oxide semiconductor film, and one or more second protective films other than the first protective film. The first protective film is a SiO.sub.x film having a hydrogen concentration of 3.5 atomic % or lower.

A Schottky barrier diode element includes an n-type or p-type silicon (Si) substrate, an oxide semiconductor layer, and a Schottky electrode layer, the oxide semiconductor layer including either or both of a polycrystalline oxide that includes gallium (Ga) as the main component and an amorphous oxide that includes gallium (Ga) as the main component.

Provided are an oxide sintered compact whereby low carrier density and high carrier mobility are obtained when the oxide sintered compact is used to obtain an oxide semiconductor thin film by a sputtering method, and a sputtering target which uses the oxide sintered compact. This oxide sintered compact contains, as an oxide, one or more positive divalent elements selected from the group consisting of indium, gallium, nickel, cobalt, calcium, strontium, and lead. The gallium content is less than 0.08 to 0.20 in terms of Ga/(In+Ga) atomic ratio, and the positive dyad (M) content is 0.0001 to 0.05 in terms of M/(In+Ga+M) atomic ratio. In a crystalline oxide semiconductor thin film formed using the oxide sintered compact as a sputtering target, the carrier density is less than 110.sup.18 cm.sup.3, and the carrier mobility is at least 10 cm.sup.2V.sup.1sec.sup.1.

Provided is an oxide sintered body that, when used to obtain an oxide semiconductor thin film by sputtering, can achieve a low carrier concentration and a high carrier mobility. Also provided is a sputtering target using the oxide sintered body. The oxide sintered body contains, as oxides, indium, gallium, and at least one positive divalent element selected from the group consisting of nickel, cobalt, calcium, strontium, and lead. The gallium content, in terms of the atomic ratio Ga/(In+Ga), is from 0.20 to 0.45, and the positive divalent element content, in terms of the atomic ratio M/(In+Ga+M), is from 0.0001 to 0.05. The amorphous oxide semiconductor thin film, which is formed using the oxide sintered body as a sputtering target, can achieve a carrier concentration of less than 3.010.sup.18 cm.sup.3 and a carrier mobility of at least 10 cm.sup.2V.sup.1 sec.sup.1.

An object is to control composition and a defect of an oxide semiconductor, another object is to increase a field effect mobility of a thin film transistor and to obtain a sufficient on-off ratio with a reduced off current. A solution is to employ an oxide semiconductor whose composition is represented by InMO.sub.3(ZnO).sub.m, where M is one or a plurality of elements selected from Ga, Fe, Ni, Mn, Co, and Al, and m is preferably a non-integer number of greater than 0 and less than 1. The concentration of Zn is lower than the concentrations of In and M. The oxide semiconductor has an amorphous structure. Oxide and nitride layers can be provided to prevent pollution and degradation of the oxide semiconductor.

Methods, systems, circuits, and devices for power-packet-switching power converters using bidirectional bipolar transistors (BTRANs) for switching. Four-terminal three-layer BTRANs provide substantially identical operation in either direction with forward voltages of less than a diode drop. BTRANs are fully symmetric merged double-base bidirectional bipolar opposite-faced devices which operate under conditions of high non-equilibrium carrier concentration, and which can have surprising synergies when used as bidirectional switches for power-packet-switching power converters. BTRANs are driven into a state of high carrier concentration, making the on-state voltage drop very low.

A semiconductor device formed using an oxide semiconductor layer and having small electrical characteristic variation is provided. A highly reliable semiconductor device including an oxide semiconductor layer and exhibiting stable electric characteristics is provided. Further, a method for manufacturing the semiconductor device is provided. In the semiconductor device, an oxide semiconductor layer is used for a channel formation region, a multilayer film which includes an oxide layer in which the oxide semiconductor layer is wrapped is provided, and an edge of the multilayer film has a curvature in a cross section.

An ESD-protective-function-equipped composite electronic component is provided that includes multiple Zener diodes formed from first and second semiconductor layers. Moreover, the second semiconductor layers are disposed on an insulating substrate and in the same plane. The electronic component includes electrodes extending from each of the Zener diodes and one or more thin-film circuit element connected in series between a pair of the electrodes.

A method for fabricating a semiconductor device comprises patterning a strained fin from a strained layer of semiconductor material arranged on a substrate, depositing a first layer of semiconductor material on the fin and exposed portions of the substrate, patterning and etching to remove a portion of the first layer of semiconductor material and a portion of the fin to expose a portion of the substrate, depositing a second layer of semiconductor material on exposed portions of the substrate and the first layer of semiconductor material, and patterning and etching to remove a portion of the second layer of semiconductor material layer and the first layer of semiconductor material to define a dummy gate stack, the dummy gate stack is operative to substantially maintain the strain in the strained fin.

A method for fabricating a semiconductor device comprises patterning a strained fin from a strained layer of semiconductor material arranged on a substrate, depositing a first layer of semiconductor material on the fin and exposed portions of the substrate, patterning and etching to remove a portion of the first layer of semiconductor material and a portion of the fin to expose a portion of the substrate, depositing a second layer of semiconductor material on exposed portions of the substrate and the first layer of semiconductor material, and patterning and etching to remove a portion of the second layer of semiconductor material layer and the first layer of semiconductor material to define a dummy gate stack, the dummy gate stack is operative to substantially maintain the strain in the strained fin.