Semiconductor laser device and method for fabricating the same

1. A method for fabricating a semiconductor laser device, the method comprising the steps of:

(a) successively depositing, on a semiconductor substrate, an active layer made of a compound semiconductor containing phosphorus and a guide layer made of a compound semiconductor;

(b) after the step (a), depositing, on the substrate, a dopant diffusion preventing layer made of a compound semiconductor containing arsenic; and

(c) after the step (b), depositing, on the substrate, a first clad layer made of a compound semiconductor containing a dopant;

(d) after the step (c), depositing, on the substrate, a current block layer made of a compound semiconductor;

(e) forming an opening configured as a stripe in the current block layer; and (f) depositing, on the substrate, a second clad layer made of a compound semiconductor containing a dopant.

2. A method for fabricating a semiconductor laser device, the method comprising the steps of:

(a) successively depositing, on a semiconductor substrate, an active layer made of a compound semiconductor containing phosphorus and a guide layer made of a compound semiconductor;

(b) depositing, on the substrate, a dopant diffusion preventing layer made of a compound semiconductor containing arsenic;

(c) depositing, on the substrate, a first clad layer made of a compound semiconductor containing a dopant;

(d) after the step (c), successively depositing, on the substrate, an etching stop layer, a second clad layer made of a compound semiconductor containing a dopant, and a cap layer;

(g) forming, on the cap layer, a mask having an opening;

(h) removing, by using the mask, respective regions of the second clad layer and the cap layer located within the opening to expose the etching stop layer in the opening; and

(i) forming, on the substrate, a current block layer made of a compound semiconductor.

3. A method for fabricating a semiconductor laser device, the method comprising the steps of:

(a) successively depositing, on a semiconductor substrate, an active layer made of a compound semiconductor containing phosphorus and a guide layer made of a compound semiconductor;

(b) depositing, on the substrate, a dopant diffusion preventing layer made of a compound semiconductor containing arsenic;

(c) depositing, on the substrate, a first clad layer made of a compound semiconductor containing a dopant;

(k) after the step (c), forming, on the substrate, a first mask having a first opening;

(l) forming, by using the first mask, a first region from which the respective regions of the dopant diffusion preventing layer and the first clad layer located within the first opening have been removed and a second region in which the dopant diffusion preventing layer and the first clad layer are deposited;

(m) depositing, on the substrate, the first clad layer again and further successively depositing an etching stop layer, a second clad layer made of a compound semiconductor containing a dopant, and a cap layer;

(n) forming a mask for dopant diffusion on the second region of the substrate and performing a thermal treatment;

(o) removing the mask for dopant diffusion and then forming a second mask having an opening extending crosswise over the first and second regions of the substrate;

(p) removing, by using the second mask, the regions of the second clad layer and the cap layer located within the second opening to expose the etching stop layer in the second opening; and

(q) forming, on the substrate, a current block layer made of a compound semiconductor.