A plurality of semiconductor layers including a light-emitting layer are formed on the main surface of a substrate which is composed of a group III-V nitride semiconductor. In one example, a calling party places a call to a called party. To design the differential pressure sensor to be resistant to overloading, the carrier plate is arranged between a first and a second diaphragm plate and has congruent concave depressions on opposite sides in the plane of the plate.