Device for detecting two different colors terms of improved operation

The substrate (3) comprises in succession a first semiconductor layer (5) having a first energy bandgap, a buffer semiconductor layer (6), a second semiconductor layer (7) having a second energy different bandgap of the first energy bandgap. Two photodetectors (1, 2) responsive to two different colors are respectively formed through the first and second semiconductor layers (5, 7). A first bias terminal (9) electrically connects the first semiconductor layer (5) in the first bias circuit (8b, 14). A second bias pad (10) electrically connects the second semiconductor layer (7) to a second bias circuit (8a, 15). The first bias block (10) being free of electrical connection with the second semiconductor layer (7).