Methods and apparatus for forming a thin film transistor (TFT) having a metal oxide layer. The method may include forming an amorphous metal oxide layer and treating the metal oxide layer with a silicon containing gas or plasma including Si.sup.4+ ions. The silicon treatment of the metal oxide layer helps fill the oxygen vacancies in the metal oxide channel layer, leading to a more stable TFT and preventing a negative threshold voltage in the TFT.

Methods of doping a semiconductor film are provided. The methods comprise epitaxially growing the III-V semiconductor film in the presence of a dopant, a surfactant capable of acting as an electron reservoir, and hydrogen, under conditions that promote the formation of a III-V semiconductor film doped with the p-type dopant. In some embodiments of the methods, the epitaxial growth of the doped III-V semiconductor film is initiated at a first hydrogen partial pressure which is increased to a second hydrogen partial pressure during the epitaxial growth process.

An epitaxial structure and a semiconductor device are provided in which the epitaxial structure includes at least a SiC substrate, a nucleation layer, and a GaN layer. The nucleation layer is formed on the SiC substrate. The material of the nucleation layer is aluminum gallium nitride doped with a dopant, the Al content in the nucleation layer changes from high to low in the thickness direction, the lattice constant of the nucleation layer is between 3.08 Å and 3.21 Å, and the doping concentration of the nucleation layer changes from high to low in the thickness direction. The GaN layer is formed on the nucleation layer.

A thin film transistor array panel includes a substrate and a gate line disposed on the substrate. The gate line includes a gate electrode. A gate insulating layer is disposed on the gate line. An oxide semiconductor layer is disposed on the gate insulating layer. The oxide semiconductor layer at least partially overlaps the gate electrode. A data line is disposed on the oxide semiconductor layer. The data line includes a source electrode and a drain electrode facing the source electrode. The oxide semiconductor layer includes tungsten, indium, zinc, or tin.

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.

Provided is a semiconductor film having a corundum-type crystal structure composed of α-Ga.sub.2O.sub.3 or an α-Ga.sub.2O.sub.3 solid solution, and an impurity concentration and/or a heterogeneous phase amount differ between a front surface and a rear surface of the semiconductor film.

The purpose of the present invention is to provide a technique of manufacturing a nitride semiconductor layer with which, when producing a semiconductor device by forming a nitride semiconductor layer on off-angle inclined substrate, it is possible to stably supply high-quality semiconductor devices by preventing occurrence of a macro step using a material that is not likely to occur lattice strains or crystal defects by mixing with GaN and does not require continuous addition; and provided is a nitride semiconductor device which comprises a nitride semiconductor layer formed on a substrate, wherein the substrate is inclined at an off angle, a rare earth element-added nitride layer to which a rare earth element is added is formed on the substrate as a primed layer, and a nitride semiconductor layer is formed on the rare earth element-added nitride layer.

Semiconductor materials can include from about 11 at % to about 50 at % of a carrier mobility contributor selected from a period 6 metal or a period 5 metal, wherein the period 6 metal is lead and the period 5 metal is indium, tin, cadmium, or a combination thereof, and wherein the carrier mobility contributor is not a combination of the period 6 metal and the period 5 metal; from about 0.6 at % to about 25 at % of an amorphous phase stabilizer, wherein the amorphous phase stabilizer is selected from indium, tin, cadmium, zinc, gallium, or a combination thereof when the carrier mobility contributor is the period 6 metal, or the amorphous phase stabilizer is selected from zinc, gallium, or a combination thereof when the carrier mobility contributor is the period 5 metal; from about 0.3 at % to about 18 at % of a semiconductivity controller including an element having a standard electrode potential from about −0.8 to about −3.05; and from about 45 at % to about 67 at % oxygen.

The characteristic of Fe-doped HEMTs is improved. The invention provides a nitride semiconductor substrate having a substrate, a buffer layer made of nitride semiconductors on the substrate, and an active layer composed of nitride semiconductor layers on the buffer layer; the buffer layer containing Fe, the Fe having a concentration profile in which the Fe concentration increases monotonically and gradually in the thickness direction of the buffer layer from an interface between the substrate and the buffer layer, has a maximum value within 2×10.sup.17 to 1.1×10.sup.20 atoms/cm.sup.3 inclusive, and decreases monotonically and gradually toward an interface between the buffer layer and the active layer, and the point of the maximum value being within ±50 nm from the midpoint in the thickness direction of the buffer layer, and being 500 nm or more away from the interface between the buffer layer and the active layer.

Provided are a GaN crystal used in a substrate for a nitride semiconductor device having a horizontal device structure such as GaN-HEMT, and a substrate used for production of a nitride semiconductor device having a horizontal device structure such as GaN-HEMT. The Gab crystal has a (0001) surface having an area of not less than 5 cm.sup.2, the (0001) surface having an inclination of not more than 10° with respect to the (0001) crystal plane, wherein the Fe concentration is not less than 5×10.sup.17 atoms/cm.sup.3 and less than 1×10.sup.9 atoms/cm.sup.3, and wherein the total donor impurity concentration is less than 5×10.sup.16 atoms/cm.sup.3.