Patent ID: 8003995

Claim:
A semiconductor optical device, comprising: an n-type semiconductor substrate; a mesa formed on said n-type semiconductor substrate; and a burying region made of InP and doped with at least one of iron (Fe) and ruthenium (Ru) for trapping electrons, said burying region burying said mesa, wherein said mesa including a first cladding layer with an n-type conduction and provided on said n-type semiconductor substrate, an active layer provided on said first cladding layer, a tunnel junction layer provided on said active layer, and a second cladding layer with said n-type conduction, said second cladding layer being provided on said tunnel junction layer, wherein said tunnel junction layer including a p-type layer and an n-type layer stacked on said active layer in this order, said n-type layer having a carrier concentration higher than a carrier concentration of said second cladding layer, said p-type layer having a thickness of 10 to 20 nm, and wherein said burying region comes into contact with no p-type layers except for said p-type layer of said tunnel junction layer within said mesa.