Provided are an oxide semiconductor layer in which the number of defects is reduced and a highly reliable semiconductor device including the oxide semiconductor. A first oxide semiconductor layer having a crystal part is formed over a substrate by a sputtering method. A second oxide semiconductor layer is formed by a thermal chemical vapor deposition method over the first oxide semiconductor layer. The second oxide semiconductor layer is formed by epitaxial growth using the first oxide semiconductor layer as a seed crystal. A channel is formed in the second oxide semiconductor layer.

To provide a novel method for manufacturing a semiconductor device. To provide a method for manufacturing a highly reliable semiconductor device at relatively low temperature. The method includes a first step of forming a first oxide semiconductor film in a deposition chamber and a second step of forming a second oxide semiconductor film over the first oxide semiconductor film in the deposition chamber. Water vapor partial pressure in an atmosphere in the deposition chamber is lower than water vapor partial pressure in atmospheric air. The first oxide semiconductor film and the second oxide semiconductor film are formed such that the first oxide semiconductor film and the second oxide semiconductor film each have crystallinity. The second oxide semiconductor film is formed such that the crystallinity of the second oxide semiconductor film is higher than the crystallinity of the first oxide semiconductor film.

A method for manufacturing a novel semiconductor device is provided. The method includes a first step of forming a first oxide semiconductor film over a substrate, a second step of heating the first oxide semiconductor film, and a third step of forming a second oxide semiconductor film over the first oxide semiconductor film. The first to third steps are performed in an atmosphere in which water vapor partial pressure is lower than water vapor partial pressure in atmospheric air, and the first step, the second step, and the third step are successively performed in this order.

Systems and methods for forming semiconductor layers, including oxide-based layers, are disclosed in which a material deposition system has a rotation mechanism that rotates a substrate around a center axis of the substrate. The system includes a heater configured to heat the substrate and a positioning mechanism that allows dynamic adjusting of an orthogonal distance, a lateral distance, and a tilt angle of an exit aperture of a material source relative to the substrate. In some embodiments, the dynamic adjusting is based on a desired layer uniformity for a desired layer growth rate. In some embodiments, the orthogonal distance, the lateral distance, or the tilt angle depends on a predetermined material ejection spatial distribution of the material source.

Semiconductor structures and methods for forming those semiconductor structures are disclosed. For example, a semiconductor structure with a p-type superlattice region, an i-type superlattice region, and an n-type superlattice region is disclosed. The semiconductor structure can have a polar crystal structure with a growth axis that is substantially parallel to a spontaneous polarization axis of the polar crystal structure. In some cases, there are no abrupt changes in polarisation at interfaces between each region. At least one of the p-type superlattice region, the i-type superlattice region and the n-type superlattice region can comprise a plurality of unit cells exhibiting a monotonic change in composition from a wider band gap (WBG) material to a narrower band gap (NBG) material or from a NBG material to a WBG material along the growth axis to induce p-type or n-type conductivity.

Systems and methods for forming semiconductor layers, including oxide-based layers, are disclosed in which a material deposition system has a rotation mechanism that rotates a substrate around a center axis of the substrate. The system includes a heater configured to heat the substrate and a positioning mechanism that allows dynamic adjusting of an orthogonal distance, a lateral distance, and a tilt angle of an exit aperture of a material source relative to the substrate. In some embodiments, the dynamic adjusting is based on a desired layer uniformity for a desired layer growth rate. In some embodiments, the orthogonal distance, the lateral distance, or the tilt angle depends on a predetermined material ejection spatial distribution of the material source.

A thin film transistor and a manufacturing method thereof, a display substrate and a display device are provided. The method of manufacturing the thin film transistor comprises forming an active layer (4) having characteristics of crystal orientation of C-axis on a substrate (1) by using indium gallium zinc oxide (InGaO.sub.3(ZnO).sub.m), where m≧2. The active layer fabricated with InGaO.sub.3(ZnO).sub.m has a good electron mobility, and the quality of the fabricated active layer is improved.

An Oxide TFT, a preparation method thereof, an array substrate and a display device are described. The method includes forming a gate electrode, a gate insulating layer, a channel layer, a barrier layer, as well as a source electrode and a drain electrode on a substrate; the channel layer is formed by depositing an amorphous oxide semiconductor film in a first mixed gas containing H.sub.2, Ar and O.sub.2. By depositing a channel layer in a first mixed gas containing H.sub.2, Ar and O.sub.2, the hysteresis phenomenon of the TFT can be mitigated effectively to improve the display quality of the display panel.

A novel metal oxide is provided. The metal oxide includes a crystal. The crystal has a structure in which a first layer, a second layer, and a third layer are stacked. The first layer, the second layer, and the third layer are each substantially parallel to a formation surface of the metal oxide. The first layer includes a first metal and oxygen. The second layer includes a second metal and oxygen. The third layer includes a third metal and oxygen. The first layer has an octahedral structure. The second layer has a trigonal bipyramidal structure or a tetrahedral structure. The third layer has a trigonal bipyramidal structure or a tetrahedral structure. The octahedral structure of the first layer includes an atom of the first metal at a center. The trigonal bipyramidal structure or the tetrahedral structure of the second layer includes an atom of the second metal at a center. The trigonal bipyramidal structure or the tetrahedral structure of the third layer includes an atom of the third metal at a center. The valence of the first metal is equal to the valence of the second metal. The valence of the first metal is different from the valence of the third metal.

A transistor including a channel layer including an oxide semiconductor material and methods of making the same. The transistor includes a channel layer having a first oxide semiconductor layer having a first oxygen concentration, a second oxide semiconductor layer having a second oxygen concentration and a third oxide semiconductor layer having a third oxygen concentration. The second oxide semiconductor layer is located between the first semiconductor oxide layer and the third oxide semiconductor layer. The second oxygen concentration is lower than the first oxygen concentration and the third oxygen concentration.