Patent ID: 7081639

Claim:
A semiconductor photodetection detector, comprising: a semiconductor substrate of a first conductivity type; a photodetection layer formed on said semiconductor substrate; a region of a second conductivity type opposite to said first conductivity type being formed in a part of said photodetection layer; and an electrode applying an electric field to said photodetection layer via said region of said second conductivity type such that said electric field acts in a thickness direction of said photodetection layer, said photodetection layer comprising: a first semiconductor layer having a first thickness and accumulating therein a compressive strain and absorbing an optical radiation; and a second semiconductor layer having a second thickness smaller than said first thickness and accumulating therein a tensile strain, said first semiconductor layer and said second semiconductor layer being stacked alternately and repeatedly in said photodetection layer, wherein a total of said first thicknesses is smaller than a thickness value Lw below which a flat surface appears at a top surface of said photodetection layer and above which an irregular surface appears at said top surface of said photodetection layer, said thickness value Lw being represented by a relationship Lw=A×εW+L , where A takes the value of −1 μm/%, εW represents said compressive strain, and L represents a constant, and wherein the total thickness of said first and second semiconductor layers is 1.3 μm.