Abstract: A compound semiconductor device includes: an electron transit layer; an electron supply layer formed over the electron transit layer; and a GaN cap layer formed over the electron supply layer, wherein the electron supply layer includes a first layer made of i-type AlxGa1-xN (0<x<1) and a second layer made of i-type AlyGa1-yN (x<y?1) and formed over the first layer.

Abstract: A compound semiconductor device includes: a substrate; and a compound semiconductor lamination structure formed over the substrate, the compound semiconductor lamination structure including a buffer layer containing an impurity, and an active layer formed over the buffer layer.

Abstract: A semiconductor apparatus includes: a substrate; a buffer layer formed on the substrate; a strained layer superlattice buffer layer formed on the buffer layer; an electron transit layer formed of a semiconductor material on the strained layer superlattice buffer layer; and an electron supply layer formed of a semiconductor material on the electron transit layer; the strained layer superlattice buffer layer being an alternate stack of first lattice layers including AlN and second lattice layers including GaN; the strained layer superlattice buffer layer being doped with one, or two or more impurities selected from Fe, Mg and C.

Abstract: A semiconductor apparatus includes a buffer layer formed on a substrate; an SLS (Strained Layer Supperlattice) buffer layer formed on the buffer layer; an electron transit layer formed on the SLS buffer layer and formed of a semiconductor material; and an electron supply layer formed on the electron transit layer and formed of a semiconductor material. Further, the buffer layer is formed of AlGaN and includes two or more layers with different Al composition ratios, the SLS buffer layer is formed by alternately laminating a first lattice layer including AlN and a second lattice layer including GaN, and the Al composition ratio in one of the layers of the buffer layer being in contact with the SLS buffer layer is greater than or equal to an Al effective composition ratio in the SLS buffer layer.

Abstract: A semiconductor apparatus includes a substrate; a buffer layer formed on the substrate; a first semiconductor layer formed on the buffer layer; and a second semiconductor layer formed on the first semiconductor layer. Further, the buffer layer is formed of AlGaN and doped with Fe, the buffer layer includes a plurality of layers having different Al component ratios from each other, and the Al component ratio of a first layer is greater than the Al component ratio of a second layer and a Fe concentration of the first layer is less than the Fe concentration of the second layer, the first and second layers being included in the plurality of layers, and the first layer being formed on a substrate side of the second layer.

Abstract: A semiconductor device includes a buffer layer made of nitride semiconductor on a substrate, a first semiconductor layer made of nitride semiconductor on the buffer layer, a second semiconductor layer made of nitride semiconductor on the first semiconductor layer, and a gate electrode, a source electrode, and a drain electrode formed on the second semiconductor layer, wherein the buffer layer has elements doped therein that include both an element selected from a group consisting of C, Mg, Fe, and Co and an element selected from a group consisting of Si, Ge, Sn, and O.

Abstract: A semiconductor device including a high resistance layer formed on a substrate, the high resistance layer being formed with a semiconductor material doped with as impurity element that makes the semiconductor material highly resistant; a multilayer intermediate layer formed on the high resistance layer; an electron transit layer formed with a semiconductor material on the multilayer intermediate layer; and an electron supply layer formed with a semiconductor material on the electron transit layer, wherein the multilayer intermediate layer is formed with a multilayer film in which a GaN layer and an AlN layer are alternately laminated.

Abstract: A semiconductor device includes a first semiconductor layer formed on a substrate, the first semiconductor containing an impurity element; a second semiconductor layer formed on the first semiconductor layer; a third semiconductor layer formed on the second semiconductor layer; and a gate electrode, a source electrode and a drain electrode that are formed on the third semiconductor layer. In the semiconductor device, the second semiconductor layer includes an impurity diffusion region in which an impurity element contained in the first semiconductor layer is diffused, the impurity diffusion region being located directly beneath the gate electrode and being in contact with the first semiconductor layer, and the impurity element causes the impurity diffusion region to be a p-type impurity diffusion region.

Abstract: A compound semiconductor device includes: a substrate; and a compound semiconductor lamination structure formed over the substrate, the compound semiconductor lamination structure including a buffer layer containing an impurity, and an active layer formed over the buffer layer.

Abstract: A semiconductor apparatus includes: a substrate; a buffer layer formed on the substrate; a strained layer superlattice buffer layer formed on the buffer layer; an electron transit layer formed of a semiconductor material on the strained layer superlattice buffer layer; and an electron supply layer formed of a semiconductor material on the electron transit layer; the strained layer superlattice buffer layer being an alternate stack of first lattice layers including AlN and second lattice layers including GaN; the strained layer superlattice buffer layer being doped with one, or two or more impurities selected from Fe, Mg and C.

Abstract: A semiconductor apparatus includes a buffer layer formed on a substrate; an SLS (Strained Layer Supperlattice) buffer layer formed on the buffer layer; an electron transit layer formed on the SLS buffer layer and formed of a semiconductor material; and an electron supply layer formed on the electron transit layer and formed of a semiconductor material. Further, the buffer layer is formed of AlGaN and includes two or more layers with different Al composition ratios, the SLS buffer layer is formed by alternately laminating a first lattice layer including AlN and a second lattice layer including GaN, and the Al composition ratio in one of the layers of the buffer layer being in contact with the SLS buffer layer is greater than or equal to an Al effective composition ratio in the SLS buffer layer.

Abstract: A semiconductor apparatus includes a substrate; a buffer layer formed on the substrate; a first semiconductor layer formed on the buffer layer; and a second semiconductor layer formed on the first semiconductor layer. Further, the buffer layer is formed of AlGaN and doped with Fe, the buffer layer includes a plurality of layers having different Al component ratios from each other, and the Al component ratio of a first layer is greater than the Al component ratio of a second layer and a Fe concentration of the first layer is less than the Fe concentration of the second layer, the first and second layers being included in the plurality of layers, and the first layer being formed on a substrate side of the second layer.

Abstract: An AlGaN/GaN HEMT includes: an electron transit layer; an electron supply layer formed above the electron transit layer; and a gate electrode formed above the electron supply layer, wherein a p-type semiconductor region is formed only at a site of the electron transit layer which is contained in a region below the gate electrode.

Abstract: A semiconductor device includes a first semiconductor layer formed on a substrate, a second semiconductor layer formed on the first semiconductor layer, a third semiconductor layer and a fourth semiconductor layer formed on the second semiconductor layer, a gate electrode formed on the third semiconductor layer, and a source electrode and a drain electrode contacting and formed on the fourth semiconductor layer, wherein the third semiconductor layer is formed of a semiconductor material for attaining p-type on an area just under the gate electrode, and a concentration of silicon in the fourth semiconductor layer is higher than that in the second semiconductor layer.

Abstract: A compound semiconductor device includes: a substrate; a GaN compound semiconductor multilayer structure disposed over the substrate; and a stress relief layer which is AlN-based and which is disposed between the substrate and the GaN compound semiconductor multilayer structure, wherein a surface of the stress relief layer that is in contact with the GaN compound semiconductor multilayer structure includes recesses that have a depth of 5 nm or more and that are formed at a number density of 2×1010 cm?2 or more.

Abstract: An embodiment of a method of manufacturing a compound semiconductor device includes: forming an initial layer over a substrate; forming a buffer layer over the initial layer; forming an electron transport layer and an electron supply layer over the buffer layer; and forming a gate electrode, a source electrode and a gate electrode over the electron supply layer. The forming an initial layer includes: forming a first compound semiconductor film with a flow rate ratio being a first value, the flow rate ratio being a ratio of a flow rate of a V-group element source gas to a flow rate of a III-group element source gas; and forming a second compound semiconductor film with the flow rate ratio being a second value different from the first value over the first compound semiconductor film. The method further includes forming an Fe-doped region between the buffer layer and the electron transport layer.

Abstract: A semiconductor device includes: a nucleation layer formed over a substrate; a buffer layer formed over the nucleation layer; a first nitride semiconductor layer formed over the buffer layer; and a second nitride semiconductor layer formed over the first nitride semiconductor layer, wherein the ratio of yellow luminescence emission to band edge emission in photoluminescence is 400% or less and the twist value in an X-ray rocking curve is 1,000 arcsec or less.

Abstract: A compound semiconductor device includes a substrate; an initial layer formed over the substrate; and a core layer which is formed over the initial layer and contains a Group III-V compound semiconductor. The initial layer is a layer of Group III atoms of the Group III-V compound semiconductor contained in the core layer.

Abstract: A semiconductor device including a high resistance layer formed on a substrate, the high resistance layer being formed with a semiconductor material doped with an impurity element that makes the semiconductor material highly resistant; a multilayer intermediate layer formed on the high resistance layer; an electron transit layer formed with a semiconductor material on the multilayer intermediate layer; and an electron supply layer formed with a semiconductor material on the electron transit layer, wherein the multilayer intermediate layer is formed with a multilayer film in which a GaN layer and an AlN layer are alternately laminated.

Abstract: A semiconductor device includes a first semiconductor layer formed on a substrate, the first semiconductor containing an impurity element; a second semiconductor layer formed on the first semiconductor layer; a third semiconductor layer formed on the second semiconductor layer; and a gate electrode, a source electrode and a drain electrode that are formed on the third semiconductor layer. In the semiconductor device, the second semiconductor layer includes an impurity diffusion region in which an impurity element contained in the first semiconductor layer is diffused, the impurity diffusion region being located directly beneath the gate electrode and being in contact with the first semiconductor layer, and the impurity element causes the impurity diffusion region to be a p-type impurity diffusion region.