Semiconductor light receiving device for repeatedly propagating incident light in light absorption layer and method for manufacturing the same

A semiconductor light receiving device comprising:

• a substrate;
• a lower cladding layer, a light absorption layer and an upper cladding layer laminated on the substrate in the order;
• a light incident end surface formed on both end surfaces of the substrate and the lower cladding layer;
• and
• a p electrode and an n electrode which output an electric signal generated by the fact that a light incident from the light incident end surface is absorbed in the light absorption layer to the outside via the upper cladding layer and the lower cladding layer, respectively,
• wherein, in order that, after the light incident on the light incident end surface is refracted at the light incident end surface and then is made obliquely incident on the light absorption layer to be propagated, the light is totally reflected at an interface of an upper side of the light absorption layer or at an interface of a semiconductor layer positioned at an upper side of the light absorption layer to be propagated obliquely downward through the light absorption layer again,
• a refractive index of the lower cladding layer is set to be higher than a refractive index of the upper cladding layer.

A method of manufacturing a semiconductor light receiving device, comprising:

• providing a substrate;
• laminating a lower cladding layer having a predetermined refractive index and constituted of at least one layer on an upper portion of the substrate;
• laminating a light absorption layer on an upper portion of the lower cladding layer;
• laminating an upper cladding layer having a refractive index smaller than a refractive index of said at least one layer constituting the lower cladding layer and constituted of at least one layer above the light absorption layer;
• making a light incident on both the substrate and the lower cladding layer at a predetermined angle to provide a light incident end surface which enables the light to be absorbed in the light absorption layer and to be output as a current,
• wherein the light incident on both the substrate and the lower cladding layer providing the light incident end surface senses a refractive index of the lower cladding layer so that an equivalent refractive index of the light becomes larger, and the equivalent refractive index of the light becomes larger than a refractive index of said at least one layer constituting the upper cladding layer having a refractive index smaller than a refractive index of said at least one layer constituting the lower cladding layer, and
• the predetermined angle is an angle enabling a light incident on the light absorption layer to be reflected at a lower surface of said at least one layer constituting the upper cladding layer,
• so that the light can be repeatedly propagated through the light absorption layer.