Abstract: A mesa photodiode which includes a mesa, the side wall of the mesa (a light-receiving region mesa) and at least a shoulder portion of the mesa in an upper face of the mesa are continuously covered with a semiconductor layer of a first conductivity type, a second conductivity type, a semi-insulating type, or an undoped type (an undoped InP layer, for example) that is grown on the side wall and the upper face of the mesa. In the semiconductor layer, a layer thickness D1 of a portion covering the side wall of the mesa is equal to or greater than 850 nm.

Abstract: A mesa photodiode which includes a mesa, the sidewall of the mesa is a surface that is inclined in the direction in which the bottom of the mesa becomes wider. At least the sidewall of the mesa is covered with a semiconductor layer of a first conductivity type, a second conductivity type, a semi-insulating type, or an undoped type. The semiconductor layer is grown on at least the sidewall of the mesa. The inclined angle of the inclined surface of the mesa at the upper end portion is smaller than the inclined angle of the inclined surface of the mesa at the lower end portion.

Abstract: According to an exemplary aspect of the present invention, at least a semiconductor mesa and a semiconductor layer covering at least the side wall of the mesa and a semiconductor mesa are formed on an n-type semiconductor substrate. The semiconductor mesa includes at least a light absorption layer and a p-type contact layer. The principal surface of the semiconductor substrate tilts at an angle ? to the (100) plane. The angle ? is 0.1 degree?|?|?10 degrees.

Abstract: A mesa photodiode which includes a mesa, the side wall of the mesa (a light-receiving region mesa) and at least a shoulder portion of the mesa in an upper face of the mesa are continuously covered with a semiconductor layer of a first conductivity type, a second conductivity type, a semi-insulating type, or an undoped type (an undoped InP layer, for example) that is grown on the side wall and the upper face of the mesa. In the semiconductor layer, a layer thickness D1 of a portion covering the side wall of the mesa is equal to or greater than 850 nm.

Abstract: A mesa photodiode which includes a mesa, the sidewall of the mesa is a surface that is inclined in the direction in which the bottom of the mesa becomes wider. At least the sidewall of the mesa is covered with a semiconductor layer of a first conductivity type, a second conductivity type, a semi-insulating type, or an undoped type. The semiconductor layer is grown on at least the sidewall of the mesa. The inclined angle of the inclined surface of the mesa at the upper end portion is smaller than the inclined angle of the inclined surface of the mesa at the lower end portion.