SEMICONDUCTOR DEVICE, ITS MANUFACTURING METHOD, METHOD OF MANUFACTURING MOUNTED ASSEMBLY AND MOUNTED ASSEMBLY

PROBLEM TO BE SOLVED: To solve the problem that the dark current are apt to flow in the conventional semiconductor device with a mesa-structured avalanche photodiode. SOLUTION: The device comprises a substrate 14 made of a compound semiconductor, a mesa-structured avalanche photodiode which is disposed on the substrate 14 and has a superlattice multiplier layer 17, an electric field relaxation layer 18, and a light absorption layer 19; and an insulation oxide protective layer 16 substantially covering all the end faces of the mesa structure. This inactivates dangling bonds (defects) 3 at mesa etched parts (end faces of the mesa structure) and shuts off the water molecules. Thus, the dark current hardly flows and hence a mounted assembly provided with the semiconductor device having the mesa-structured avalanche photodiode can be manufactured without specific hermetical sealing.