Semiconductor laser diode and method of manufacturing the same

Abstract

Provided are a semiconductor laser diode and a method of manufacturing the same. The semiconductor laser diode includes a lower cladding layer disposed on a substrate; a ridge including an optical waveguide layer, an active layer, an upper cladding layer, and an ohmic contact layer, which are sequentially stacked on the lower cladding layer, and having a predetermined width, which is obtained by performing a channel etching process on both sides of the ridge; an oxide layer disposed on surfaces of the upper and lower cladding layer to control the width of the ridge; a dielectric layer disposed on left and right channels of the ridge; an upper electrode layer disposed on the entire surface of the resultant structure to enclose the ridge and the dielectric layer; and a lower electrode layer disposed on a bottom surface of the substrate. The method is simpler than a conventional process of manufacturing a semiconductor laser diode. Also, by controlling a wet oxidation time, the width of a ridge can be freely controlled and an ohmic contact layer can be automatically formed.

What is claimed is: 
     
       1. A semiconductor laser diode comprising:
 a lower cladding layer comprising InAlAs disposed on a substrate; 
 a ridge including an optical waveguide layer, a quantum dot active layer, an upper cladding layer comprising InAlAs, and an ohmic contact layer, which are sequentially stacked on the lower cladding layer, and having a predetermined width, which is obtained by performing a channel etching process on both sides of the ridge, wherein the ridge also includes a portion of the lower cladding layer; 
 an oxide layer formed by oxidizing surfaces of the upper and lower cladding layer to control an effective width of the ridge; 
 a dielectric layer disposed on left and right channels of the ridge; 
 an upper electrode layer disposed on the entire surface of the resultant structure to enclose the ridge and the dielectric layer; and 
 a lower electrode layer disposed on a bottom surface of the substrate, 
 wherein the upper and lower cladding layers have a faster oxidation rate than that of the optical waveguide layer and active layer so that the formation of the oxide layer substantially changes the effective width of the ridge without substantially changing the predetermined width of the active layer or the optical waveguide layer. 
 
     
     
       2. The semiconductor laser diode according to  claim 1 , further comprising an additional optical waveguide layer interposed between the active layer and the upper cladding layer. 
     
     
       3. The semiconductor laser diode according to  claim 1 , wherein the upper and lower cladding layers are a p-type InAlAs layer and an n-type InAlAs layer, respectively, which are lattice-matched to the substrate. 
     
     
       4. The semiconductor laser diode according to  claim 3 , wherein each of the upper and lower cladding layers is formed to a thickness of about 1 to 2 μm. 
     
     
       5. The semiconductor laser diode according to  claim 1 , wherein the optical waveguide layer is an undoped InAlGaAs layer having a separate confinement heterostructure (SCH) structure, which is lattice-matched to the substrate. 
     
     
       6. The semiconductor laser diode according to  claim 5 , wherein the optical waveguide layer is formed to a thickness of about 130 to 170 nm. 
     
     
       7. The semiconductor laser diode according to  claim 1 , wherein the active layer is obtained by repetitively forming InAs quantum dots, which are spontaneously formed from InAs that is lattice-mismatched to the substrate, and an undoped InAlGaAs barrier layer, which is lattice-matched to the substrate, in several cycles. 
     
     
       8. The semiconductor laser diode according to  claim 1 , wherein the ohmic contact layer is a p-type InGaAs layer, which is lattice-matched to the substrate. 
     
     
       9. The semiconductor laser diode according to  claim 8 , wherein the ohmic contact layer is formed to a thickness of about 130 to 170 nm. 
     
     
       10. A semiconductor laser diode comprising:
 a lower cladding layer comprising InAlAs disposed on a substrate;   a ridge including an optical waveguide layer, a quantum dot active layer, an upper cladding layer comprising InAlAs, and an ohmic contact layer, which are sequentially stacked on the lower cladding layer, and having a predetermined width, which is obtained by performing a channel etching process on both sides of the ridge, wherein the ridge also includes a portion of the lower cladding layer;   an oxide layer formed by oxidizing surfaces of the upper and lower cladding layer to control an effective width of the ridge;   a dielectric layer disposed on left and right channels of the ridge;   an upper electrode layer disposed on the entire surface of the resultant structure to enclose the ridge and the dielectric layer; and   a lower electrode layer,   wherein the upper and lower cladding layers have a faster oxidation rate than that of the optical waveguide layer and active layer so that the formation of the oxide layer substantially changes the effective width of the ridge without substantially changing the predetermined width of the active layer or the optical waveguide layer.   
     
     
       11. A semiconductor laser diode comprising:
 a lower cladding layer disposed on a substrate;   a ridge having a predetermined width, wherein the ridge comprises:
 an optical waveguide layer, an active layer, and an upper cladding layer, which are stacked on the lower cladding layer, and 
 a portion of the lower cladding layer; and 
   an oxide layer formed by oxidizing surfaces of the upper and lower cladding layers,
 wherein the upper and lower cladding layers have a faster oxidation rate than that of the optical waveguide layer and the active layer so that the formation of the oxide layer substantially changes an effective width of the ridge without substantially changing the predetermined width of the active layer or the optical waveguide layer. 
   
     
     
       12. The semiconductor laser diode according to claim 11, wherein the lower and upper cladding layers comprise InAlAs. 
     
     
       13. The semiconductor laser diode according to claim 11, wherein the active layer is a quantum dot active layer. 
     
     
       14. The semiconductor laser diode according to claim 11, wherein the ridge is obtained by performing a channel etching process on both sides of the ridge. 
     
     
       15. The semiconductor laser diode according to claim 11, further comprising:
 a dielectric layer disposed on at least one side of the ridge;   an upper electrode layer disposed on a surface of the dielectric layer, wherein the upper electrode layer encloses the ridge; and   a lower electrode layer disposed on a bottom surface of the substrate.   
     
     
       16. The semiconductor laser diode according to claim 11, further comprising an additional optical waveguide layer interposed between the active layer and the upper cladding layer. 
     
     
       17. The semiconductor laser diode according to claim 11, wherein the upper and lower cladding layers are a p-type InAlAs layer and an n-type InAlAs layer, respectively, which are lattice-matched to the substrate. 
     
     
       18. The semiconductor laser diode according to claim 11, wherein each of the upper and lower cladding layers is formed to a thickness of about 1 to 2 μm. 
     
     
       19. The semiconductor laser diode according to claim 11, wherein the optical waveguide layer is undoped InAlGaAs layer having a separate confinement heterostructure (SCH) structure, which is lattice-matched to the substrate. 
     
     
       20. The semiconductor laser diode according to claim 11, wherein the optical waveguide layer is formed to a thickness of about 130 to 170 nm. 
     
     
       21. The semiconductor laser diode according to claim 11, wherein the active layer is obtained by repetitively forming InAs quantum dots, which are spontaneously formed from InAs that is lattice-mismatched to the substrate, and an undoped InAlGaAs barrier layer, which is lattice-matched to the substrate, in several cycles. 
     
     
       22. The semiconductor laser diode according to claim 11, further comprising a contact layer, wherein the contact layer is a p-type InGaAs layer, which is lattice-matched to the substrate. 
     
     
       23. The semiconductor laser diode according to claim 22, wherein the contact layer is formed to a thickness of about 130 to 170 nm. 
     
     
       24. The semiconductor laser diode according to claim 11, wherein the oxide layer is configured to control the effective width of the ridge. 
     
     
       25. A semiconductor laser diode comprising:
 a lower cladding layer disposed on a substrate;   a ridge having a predetermined width, wherein the ridge comprises:
 an optical waveguide layer, an active layer, and an upper cladding layer, which are stacked on the lower cladding layer, and 
 a portion of the lower cladding layer; 
   a first oxide layer formed at one side of the upper cladding layer; and   a second oxide layer formed at one side of the lower cladding layer,
 wherein the upper and lower cladding layers have a faster oxidation rate than that of the optical waveguide layer and the active layer. 
   
     
     
       26. The semiconductor laser diode according to claim 25, wherein the first and the second oxide layers are formed by oxidizing surfaces of the upper and lower cladding layers, respectively. 
     
     
       27. The semiconductor laser diode according to claim 26, wherein the first and the second oxide layers substantially change an effective width of the ridge without substantially changing the predetermined width of the active layer or the optical waveguide layer. 
     
     
       28. The semiconductor laser diode according to claim 25, wherein the lower and upper cladding layers comprise InAlAs. 
     
     
       29. The semiconductor laser diode according to claim 25, wherein the active layer is a quantum dot active layer. 
     
     
       30. The semiconductor laser diode according to claim 25, further comprising:
 a dielectric layer disposed on at least one side of the ridge;   an upper electrode layer disposed on a surface of the dielectric layer, wherein the upper electrode layer encloses the ridge; and   a lower electrode layer disposed on a bottom surface of the substrate.   
     
     
       31. A semiconductor laser diode comprising:
 a lower cladding layer disposed on a substrate; and   a ridge comprising a portion of the lower cladding layer, an optical waveguide layer, an active layer, and an upper cladding layer, wherein:
 the upper cladding layer comprises an oxidated portion and a non-oxidated portion, 
 a width of the non-oxidated portion of the upper cladding layer is smaller than a width of the optical waveguide layer and a width of the active layer, and 
 the upper and lower cladding layers have a faster oxidation rate than that of the optical waveguide layer and active layer. 
   
     
     
       32. The semiconductor laser diode according to claim 31, wherein the oxidated portion is formed by oxidizing a surface of the upper cladding layer. 
     
     
       33. The semiconductor laser diode according to claim 31, wherein the oxidated portion substantially changes an effective width of the ridge without substantially changing a width of the active layer or the optical waveguide layer. 
     
     
       34. The semiconductor laser diode according to claim 31, wherein the lower and upper cladding layers comprise InAlAs. 
     
     
       35. The semiconductor laser diode according to claim 31, wherein the active layer is a quantum dot active layer. 
     
     
       36. The semiconductor laser diode according to claim 31, further comprising:
 a dielectric layer disposed on at least one side of the ridge;   an upper electrode layer disposed on a surface of the dielectric layer, wherein the upper electrode layer encloses the ridge; and   a lower electrode layer disposed on a bottom surface of the substrate.