Optical semiconductor device and method of fabricating the same

Abstract

A photodiode (111) and resistors (121) are formed on a semi-insulating InP substrate (101). The photodiode (111) is formed by subjecting a layered structure formed by successively depositing an n+-type InP cladding layer (102), an n-type InGaAsP core layer (103), a nondoped InGaAs active layer (104), a p-type InGaAsP core layer (105), and a p+-type InP cladding layer 106 on the InP substrate (101) to a selective etching process. The resistors (121) have the same layered structure as the photodiode (111). Photodiode (111) is connected to n-type wiring lines (131) and a p-type wiring line (141). Resistors (121) are connected to the n-type wiring lines (131) and the p-type wiring line (141) in parallel to the photodiode (111). A side surface on the side of the photodiode (111) of the InP substrate (101) is a cleavage plane, and the cleavage plane is coated with an antireflection film (161). Since the resistors (121) have a p-type semiconductor layer having a high resistivity, the resistors (121) can be formed in a big width. Consequently, change of resistance corresponding to change of the width of the resistor is small and hence matching can be easily achieved.

Dependencies are inferred from the claim text.