A method for forming a power semiconductor device is provided. The method includes: providing a semiconductor wafer grown by a Czochralski process and having a first side; forming an n-type substrate doping layer in the semiconductor wafer at the first side, the substrate doping layer having a doping concentration of at least 10.sup.17/cm.sup.3; and forming an epitaxy layer on the first side of the semiconductor wafer after forming the n-type substrate doping layer.

A method for forming a power semiconductor device is provided. The method includes: providing a semiconductor wafer grown by a Czochralski process and having a first side; forming an n-type substrate doping layer in the semiconductor wafer at the first side, the substrate doping layer having a doping concentration of at least 10.sup.17/cm.sup.3; and forming an epitaxy layer on the first side of the semiconductor wafer after forming the n-type substrate doping layer.

Provided is a crystal laminate including: a crystal substrate formed from a monocrystal of group III nitride expressed by a compositional formula In.sub.xAl.sub.yGa.sub.1-x-yN (where 0x1, 0y1, 0x+y1), the crystal substrate containing at least any one of n-type impurity selected from the group consisting of Si, Ge, and O; and a crystal layer formed by a group III nitride crystal epitaxially grown on a main surface of the crystal substrate, at least any one of p-type impurity selected from the group consisting of C, Mg, Fe, Be, Zn, V, and Sb being ion-implanted in the crystal layer. The crystal laminate is configured in a manner such that an absorption coefficient of the crystal substrate for light with a wavelength of 2000 nm when the crystal substrate is irradiated with the light falls within a range of 1.8 cm.sup.1 or more and 4.6 cm.sup.1 or less under a temperature condition of normal temperature.

Provided is a crystal laminate including: a crystal substrate formed from a monocrystal of group III nitride expressed by a compositional formula In.sub.xAl.sub.yGa.sub.1-x-yN (where 0x1, 0y1, 0x+y1), the crystal substrate containing at least any one of n-type impurity selected from the group consisting of Si, Ge, and O; and a crystal layer formed by a group III nitride crystal epitaxially grown on a main surface of the crystal substrate, at least any one of p-type impurity selected from the group consisting of C, Mg, Fe, Be, Zn, V, and Sb being ion-implanted in the crystal layer. The crystal laminate is configured in a manner such that an absorption coefficient of the crystal substrate for light with a wavelength of 2000 nm when the crystal substrate is irradiated with the light falls within a range of 1.8 cm.sup.1 or more and 4.6 cm.sup.1 or less under a temperature condition of normal temperature.

Methods are provided for separating a crystalline film from its main body. The method uses ion implantation to generate an ion damaged layer underneath the surface of the crystalline object. The ion damage changes the crystal structure of the ion damaged layer, so it will have different optical transmittance and absorption characteristics from the undamaged part of the crystalline object. A laser beam with a wavelength that is higher than the absorption edge of the non-ion damaged material, but within the absorption range of the ion damaged material is irradiated at or past the ion damaged layer, causing further damage to the ion damaged layer. The film can then be separated from the main body of the crystalline object.

Methods are provided for separating a crystalline film from its main body. The method uses ion implantation to generate an ion damaged layer underneath the surface of the crystalline object. The ion damage changes the crystal structure of the ion damaged layer, so it will have different optical transmittance and absorption characteristics from the undamaged part of the crystalline object. A laser beam with a wavelength that is higher than the absorption edge of the non-ion damaged material, but within the absorption range of the ion damaged material is irradiated at or past the ion damaged layer, causing further damage to the ion damaged layer. The film can then be separated from the main body of the crystalline object.

A nitride semiconductor laminate includes: a substrate comprising a group III nitride semiconductor and including a surface and a reverse surface, the surface being formed from a nitrogen-polar surface, the reverse surface being formed from a group III element-polar surface and being provided on the reverse side from the surface; a protective layer provided at least on the reverse surface side of the substrate and having higher heat resistance than the reverse surface of the substrate; and a semiconductor layer provided on the surface side of the substrate and comprising a group III nitride semiconductor. The concentration of O in the semiconductor layer is lower than 110.sup.17 at/cm.sup.3.

A nitride semiconductor laminate includes: a substrate comprising a group III nitride semiconductor and including a surface and a reverse surface, the surface being formed from a nitrogen-polar surface, the reverse surface being formed from a group III element-polar surface and being provided on the reverse side from the surface; a protective layer provided at least on the reverse surface side of the substrate and having higher heat resistance than the reverse surface of the substrate; and a semiconductor layer provided on the surface side of the substrate and comprising a group III nitride semiconductor. The concentration of O in the semiconductor layer is lower than 110.sup.17 at/cm.sup.3.

A method of manufacturing a diamond by a vapor phase synthesis method includes: preparing a substrate including a diamond seed crystal; forming a light absorbing layer lower in optical transparency than the substrate by performing ion implantation into the substrate, the light absorbing layer being formed at a predetermined depth from a main surface of the substrate; growing a diamond layer on the main surface of the substrate by the vapor phase synthesis method; and separating the diamond layer from the substrate by applying light from a main surface of at least one of the diamond layer and the substrate to allow the light absorbing layer to absorb the light and cause the light absorbing layer to be broken up.

A method of manufacturing a diamond by a vapor phase synthesis method includes: preparing a substrate including a diamond seed crystal; forming a light absorbing layer lower in optical transparency than the substrate by performing ion implantation into the substrate, the light absorbing layer being formed at a predetermined depth from a main surface of the substrate; growing a diamond layer on the main surface of the substrate by the vapor phase synthesis method; and separating the diamond layer from the substrate by applying light from a main surface of at least one of the diamond layer and the substrate to allow the light absorbing layer to absorb the light and cause the light absorbing layer to be broken up.