Light-receiving device and method for producing the same

A method for producing a light-receiving device, the method comprising the steps of:

• growing a light-receiving layer on a substrate, the light-receiving layer having an undoped multi-quantum well structure;
• growing a cap layer on the light-receiving layer, the cap layer including a p-type semiconductor layer doped with a p-type impurity;
• forming a mesa structure by etching the cap layer, the mesa structure being defined by a trench surrounding the mesa;
• after the step of forming the mesa structure, forming a protective film on an upper surface and a side surface of the mesa structure;
• and
• after the step of forming the protective film, forming a p-n junction in the light-receiving layer or at the boundary between the light-receiving layer and the cap layer by annealing with the upper surface and the side surface of the mesa structure covered with the protective film at a predetermined temperature,
• wherein, in the step of forming the mesa structure, the trench reaches the vicinity of an upper surface of the light-receiving layer, and
• in the step of forming the p-n junction, the p-type impurity in the p-type semiconductor layer is diffused from the cap layer in the mesa structure to the light-receiving layer.

A method for producing a light-receiving device, the method comprising the steps of:

• growing a light-receiving layer on a substrate, the light-receiving layer having an undoped multi-quantum well structure;
• forming a selective growth mask on the light-receiving layer, the selective growth mask including an opening through which the light-receiving layer is exposed;
• selectively growing a concentration adjusting layer and a p-type contact layer, in that order, on the light-receiving layer using the selective growth mask, the p-type contact layer being doped with a p-type impurity;
• and
• forming a p-n junction in the light-receiving layer or at the boundary between the light-receiving layer and the concentration adjusting layer,
• wherein the concentration adjusting layer is not doped or is doped with a p-type or an n-type impurity at a lower concentration than that of the p-type contact layer, and
• in the step of forming the p-n junction, the p-type impurity doped in the p-type contact layer is diffused to the light-receiving layer through the concentration adjusting layer during growing the p-type contact layer.