Semiconductor optical device and manufacturing method thereof
View Patent ↗The object of the invention is to reduce the deterioration of crystallinity in the vicinity of an active layer when C, which is a p-type dopant, is doped and to suppress the diffusion of Zn, which is a p-type dopant, into an undoped active layer, thus to realize a sharp doping profile. When a Zn-doped InGaAlAs layer having favorable crystallinity is provided between a C-doped InGaAlAs upper-side guiding layer and an undoped active layer, the influence of the C-doped InGaAlAs layer whose crystallinity is lowered can be reduced in the vicinity of the active layer. Further, the Zn diffusion from a Zn-doped InP cladding layer can be suppressed by the C-doped InGaAlAs layer.
1. A method for manufacturing a semiconductor optical device, the method comprising:
a step of preparing a semiconductor substrate; and
a step of forming an n-type cladding layer, an undoped active layer, a Zn-doped guide layer, and a C-doped cladding layer on the semiconductor substrate in a sequential order,
wherein, prior to forming the C-doped cladding layer on the Zn-doped guide layer, film growth is stopped at a location spaced from an interface between the active layer and the guide layer to decrease a film growing temperature from a temperature used to form the Zn-doped guide layer to a temperature used to form the C-doped cladding layer.
2. The method for manufacturing a semiconductor optical device according to claim 1 , wherein the semiconductor substrate is comprised of GaAs, the n-type cladding layer is comprised of AlGaAs, and the active layer is comprised of AlGaAs/AlGaAs or GaAs/AlGaAs, and wherein the C-doped layer and the Zn-doped layer are both included in a p-type cladding layer and are both comprised of GaAlAs.
3. The method for manufacturing a semiconductor optical device according to claim 1 , wherein the C-doped cladding layer is included in a p-type cladding layer and wherein a concentration of C which is doped into the C-doped cladding layer included in the p-type cladding layer falls within a range of from 5×10 17 to 5×10 18 cm −3 .
4. The method for manufacturing a semiconductor optical device according to claim 1 , wherein the film growth is stopped after the growth of the Zn-doped guide layer and prior to the forming of the C-doped cladding layer.
5. A method of manufacturing a semiconductor optical device according to claim 4 , wherein the film growth is stopped in a Zn-doped composition gradient layer formed between the Zn-doped guide layer and the C-doped cladding layer.