Abstract: An avalanche photodiode capable of generating a minimal surface leakage current as well as achieving a uniform electrical field. The avalanche photodiode includes a semiconductor substrate provided with a lower electrode underneath it, an amplification layer producing pairs of electron-holes through ionized collision of carriers injected by an internal electrical field, and an absorption layer producing the carriers according to splitting of the pairs of electron-holes by the electrical field. The avalanche photodiode further includes a contact layer formed on the absorption layer, with a core section in the center of the contact layer and a guard section surrounding the core section spaced apart from each other, and at least one upper electrode with a core electrode formed on the core section and a guard electrode formed on the guard section. The upper electrode generates the internal electrical field together with the lower electrode.

Abstract: An avalanche photodiode capable of generating a minimal surface leakage current as well as achieving a uniform electrical field. The avalanche photodiode includes a semiconductor substrate provided with a lower electrode underneath it, an amplification layer producing pairs of electron-holes through ionized collision of carriers injected by an internal electrical field, and an absorption layer producing the carriers according to splitting of the pairs of electron-holes by the electrical field. The avalanche photodiode further includes a contact layer formed on the absorption layer, with a core section in the center of the contact layer and a guard section surrounding the core section spaced apart from each other, and at least one upper electrode with a core electrode formed on the core section and a guard electrode formed on the guard section. The upper electrode generates the internal electrical field together with the lower electrode.

Abstract: A semiconductor device with a heterojunction structure having a substrate and a crystal layer which is grown over the substrate, in which a quantum dot buffer layer is interposed between the substrate and the crystal layer. In the semiconductor device, the interposition of the quantum dot buffer layer between the substrate and the crystal layer can effectively eliminate lattice mismatch between the substrate and the crystal layer. Therefore, a semiconductor device having excellent electro-optical characteristics can be obtained.