The diode of claim 1, wherein the high barrier region comprises AlGaN layer implanted with Mg, Cd, Zn, Ca, N, O, C, Ar or a silicon oxide layer.

The diode of claim 1, further comprising a dielectric layer formed on the AlGaN layer, the dielectric layer having an opening in which the metal layer is formed as the anode electrode.

The diode of claim 1, wherein the substrate comprises an insulating substrate. withdrawn

The diode of claim 1, wherein the substrate comprises a conducting substrate.

The diode of claim 1, wherein the substrate eempises an i l is formed of a material selected from sapphire, ZnO, A l N, GaN, SiC or g l ass.

The diode of claim 1, wherein the high barrier region comprises a first high barrier region and a second high barrier region positioned under a first edge and a second edge, respectively, of the metal layer, and the metal layer comprises a first metal layer positioned between an inner boundary of the first high barrier region and the inner boundary of the second high barrier region, and a second metal layer formed on top of and enclosing the first metal layer.

The diode of claim 1, wherein the high barrier region is formed by ion-implantation into the AlGaN layer, diffusion into the AlGaN layer, or plasma exposure.

The diode of claim 1, wherein the high barrier region comprises AlGaN layer implanted with Mg, Cd, Zn, Ca, N, O, C, Ar or a silicon oxide layer.

The diode of claim 1, further comprising a dielectric layer formed on the AlGaN layer, the dielectric layer having an opening in which the metal layer is formed as the anode electrode.

The diode of claim 1, wherein the substrate comprises an insulating substrate. withdrawn

The diode of claim 1, wherein the substrate comprises a conducting substrate.

The diode of claim 1, wherein the substrate eempises an i l is formed of a material selected from sapphire, ZnO, A l N, GaN, SiC or g l ass.

The diode of claim 1, wherein the high barrier region comprises a first high barrier region and a second high barrier region positioned under a first edge and a second edge, respectively, of the metal layer, and the metal layer comprises a first metal layer positioned between an inner boundary of the first high barrier region and the inner boundary of the second high barrier region, and a second metal layer formed on top of and enclosing the first metal layer.

The diode of claim 1, wherein the high barrier region is formed by ion-implantation into the AlGaN layer, diffusion into the AlGaN layer, or plasma exposure.

The diode of claim 1, wherein the high barrier region comprises AlGaN layer implanted with Mg, Cd, Zn, Ca, N, O, C, Ar or a silicon oxide layer.

The diode of claim 1, further comprising a dielectric layer formed on the AlGaN layer, the dielectric layer having an opening in which the metal layer is formed as the anode electrode.

The diode of claim 1, wherein the substrate comprises an insulating substrate. withdrawn

The diode of claim 1, wherein the substrate comprises a conducting substrate.

The diode of claim 1, wherein the substrate eempises an i l is formed of a material selected from sapphire, ZnO, A l N, GaN, SiC or g l ass.

The diode of claim 1, wherein the high barrier region comprises a first high barrier region and a second high barrier region positioned under a first edge and a second edge, respectively, of the metal layer, and the metal layer comprises a first metal layer positioned between an inner boundary of the first high barrier region and the inner boundary of the second high barrier region, and a second metal layer formed on top of and enclosing the first metal layer.

The diode of claim 1, wherein the high barrier region is formed by ion-implantation into the AlGaN layer, diffusion into the AlGaN layer, or plasma exposure.

The diode of claim 1, wherein the high barrier region comprises AlGaN layer implanted with Mg, Cd, Zn, Ca, N, O, C, Ar or a silicon oxide layer.

The diode of claim 1, further comprising a dielectric layer formed on the AlGaN layer, the dielectric layer having an opening in which the metal layer is formed as the anode electrode.

The diode of claim 1, wherein the substrate comprises an insulating substrate. withdrawn

The diode of claim 1, wherein the substrate comprises a conducting substrate.

The diode of claim 1, wherein the substrate eempises an i l is formed of a material selected from sapphire, ZnO, A l N, GaN, SiC or g l ass.

The diode of claim 1, wherein the high barrier region comprises a first high barrier region and a second high barrier region positioned under a first edge and a second edge, respectively, of the metal layer, and the metal layer comprises a first metal layer positioned between an inner boundary of the first high barrier region and the inner boundary of the second high barrier region, and a second metal layer formed on top of and enclosing the first metal layer.

The diode of claim 1, wherein the high barrier region is formed by ion-implantation into the AlGaN layer, diffusion into the AlGaN layer, or plasma exposure.