Side-face incidence type photo detector

A photo detector, comprising:

• a semiconductor substrate having a first principal face and a second principal face;
• a photo detection area formed on the first principal face of the semiconductor substrate;
• a negative electrode electrically connected with the photo detection area;
• a positive electrode;
• a beveled face formed on at least one edge portion of the first principal face of the semiconductor substrate;
• a reflector formed on the second principal face of the semiconductor substrate,
• a light absorbing layer on the first principal face of the semiconductor substrate;
• a window layer having a diffusion area on the light absorbing layer;
• and
• a contact hole which reaches the first principal face of the semiconductor substrate through the window layer and through the light absorbing layer;
• wherein incident light from outside of the semiconductor substrate, enters the semiconductor substrate at a side face of the photo detector while being refracted at the beveled face, and thereafter is reflected from the reflector so as to reach the photo detection area.