A p anode layer is formed on one main surface of an n.sup. drift layer. N.sup.+ cathode layer having an impurity concentration more than that of the n.sup. drift layer is formed on the other main surface. An anode electrode is formed on the surface of the p anode layer. A cathode electrode is formed on the surface of the n.sup.+ cathode layer. N-type broad buffer region having a net doping concentration more than the bulk impurity concentration of a wafer and less than the n.sup.+ cathode layer and p anode layer is formed in the n.sup. drift layer. Resistivity .sub.0 of the n.sup. drift layer satisfies 0.12V.sub.0.sub.00.25V.sub.0 with respect to rated voltage V.sub.0. Total amount of net doping concentration of the broad buffer region is equal to or more than 4.810.sup.11 atoms/cm.sup.2 and equal to or less than 1.010.sup.12 atoms/cm.sup.2.

A p anode layer is formed on one main surface of an n.sup. drift layer. N.sup.+ cathode layer having an impurity concentration more than that of the n.sup. drift layer is formed on the other main surface. An anode electrode is formed on the surface of the p anode layer. A cathode electrode is formed on the surface of the n.sup.+ cathode layer. N-type broad buffer region having a net doping concentration more than the bulk impurity concentration of a wafer and less than the n.sup.+ cathode layer and p anode layer is formed in the n.sup. drift layer. Resistivity .sub.0 of the n.sup. drift layer satisfies 0.12V.sub.0.sub.00.25V.sub.0 with respect to rated voltage V.sub.0. Total amount of net doping concentration of the broad buffer region is equal to or more than 4.810.sup.11 atoms/cm.sup.2 and equal to or less than 1.010.sup.12 atoms/cm.sup.2.

The solar cell structure according to the present invention comprises a nanowire (205) that constitutes the light absorbing part of the solar cell structure and a passivating shell (209) that encloses at least a portion of the nanowire (205). In a first aspect of the invention, the passivating shell (209) of comprises a light guiding shell (210), which preferably has a high- and indirect bandgap to provide light guiding properties. In a second aspect of the invention, the solar cell structure comprises a plurality of nanowires which are positioned with a maximum spacing between adjacent nanowires which is shorter than the wavelength of the light which the solar cell structure is intended to absorbing order to provide an effective medium for light absorption. Thanks to the invention it is possible to provide high efficiency solar cell structures.

A radial nanowire Esaki diode device includes a semiconductor core of a first conductivity type and a semiconductor shell of a second conductivity type different from the first conductivity type. The device may be a TFET or a solar cell.

A radial nanowire Esaki diode device includes a semiconductor core of a first conductivity type and a semiconductor shell of a second conductivity type different from the first conductivity type. The device may be a TFET or a solar cell.

An epitaxial wafer, a method of manufacturing the epitaxial wafer, a diode, and a current rectifier are provided. The epitaxial wafer comprises a Si substrate layer; an insulating layer formed on the Si substrate layer; and a nitride semiconductor layer formed on a surface of the insulating layer facing away from the Si substrate layer; wherein the insulating layer has a thickness configured such that under a forward bias voltage, the insulating layer may allow electrons and holes to pass from one side to the other side of the insulating layer via quantum tunneling so as to allow a forward current flow.

An epitaxial wafer, a method of manufacturing the epitaxial wafer, a diode, and a current rectifier are provided. The epitaxial wafer comprises a Si substrate layer; an insulating layer formed on the Si substrate layer; and a nitride semiconductor layer formed on a surface of the insulating layer facing away from the Si substrate layer; wherein the insulating layer has a thickness configured such that under a forward bias voltage, the insulating layer may allow electrons and holes to pass from one side to the other side of the insulating layer via quantum tunneling so as to allow a forward current flow.

A p anode layer is formed on one main surface of an n.sup. drift layer. N.sup.+ cathode layer having an impurity concentration more than that of the n.sup. drift layer is formed on the other main surface. An anode electrode is formed on the surface of the p anode layer. A cathode electrode is formed on the surface of the n.sup.+ cathode layer. N-type broad buffer region having a net doping concentration more than the bulk impurity concentration of a wafer and less than the n.sup.+ cathode layer and p anode layer is formed in the n.sup. drift layer. Resistivity .sub.0 of the n.sup. drift layer satisfies 0.12V.sub.0.sub.00.25V.sub.0 with respect to rated voltage V.sub.0. Total amount of net doping concentration of the broad buffer region is equal to or more than 4.810.sup.11 atoms/cm.sup.2 and equal to or less than 1.010.sup.12 atoms/cm.sup.2.

A p anode layer is formed on one main surface of an n.sup. drift layer. N.sup.+ cathode layer having an impurity concentration more than that of the n.sup. drift layer is formed on the other main surface. An anode electrode is formed on the surface of the p anode layer. A cathode electrode is formed on the surface of the n.sup.+ cathode layer. N-type broad buffer region having a net doping concentration more than the bulk impurity concentration of a wafer and less than the n.sup.+ cathode layer and p anode layer is formed in the n.sup. drift layer. Resistivity .sub.0 of the n.sup. drift layer satisfies 0.12V.sub.0.sub.00.25V.sub.0 with respect to rated voltage V.sub.0. Total amount of net doping concentration of the broad buffer region is equal to or more than 4.810.sup.11 atoms/cm.sup.2 and equal to or less than 1.010.sup.12 atoms/cm.sup.2.

A semiconductor device includes a substrate, a two-dimensional (2D) material layer formed on the substrate and having a first region and a second region adjacent to the first region, and a source electrode and a drain electrode provided to be respectively in contact with the first region and the second region of the 2D material layer, the second region of the 2D material layer including an oxygen adsorption material layer in which oxygen is adsorbed on a surface of the second region.