SEMICONDUCTOR LASER DIODE DEVICE AND MANUFACTURING METHOD THEREOF

Abstract

The present disclosure provides fabrication of a laser diode with reliability at a high temperature of 80° C. or more in a high-power single mode by a process of thinly growing a second upper clad (P clad) layer at 1 μm or less in primary growth, appropriately controlling an upper portion Wt to 1.5 μm or more and a lower portion Wb to 4.0 μm or less of the wave guide, and then compensating for a second upper clad layer to 0.5 μm or more in regrowth, in order to compensate for disadvantages of a high-power and high-reliability laser diode device with a thick second upper clad layer (P clad). A second upper clad regrowth layer is applied to reduce internal resistance and voltage and reduce heat generated in the device to increase a Kink and a COD power, thereby improving the performance of a high-power and high-reliability laser diode.

Claims

1. A semiconductor laser diode device comprising: a semiconductor substrate; a lower clad layer formed on the semiconductor substrate; an active layer formed on the lower clad layer; a first upper clad layer formed on the active layer; an etch stop layer formed on the first upper clad layer; a second upper clad layer formed on the etch stop layer; and an anti-oxidation layer formed on the second upper clad layer, as primary growth, a mesa wave guide formed by partially removing the anti-oxidation layer and a current blocking layer through a mask; and a current blocking layer formed on a side surface of the wave guide, as secondary growth, a second upper clad regrowth layer formed by removing the mask; and a contact layer continuously formed on the second upper clad regrowth layer, as a tertiary growth.

2. The semiconductor laser diode device of claim 1, wherein the second upper clad layer is thinly grown at a thickness of 1.0 μm or less and the second upper clad regrowth layer is grown to compensate for the thickness of the second upper clad layer by the second upper clad regrowth layer for high power and high reliability.

3. The semiconductor laser diode device of claim 1, wherein an AlGaAs barrier with a high refractive index is inserted into the active layer to have a double barrier separate confinement heterostructure (DBSCH) of slightly controlling a far field vertical (FFV) mode.

4. The semiconductor laser diode device of claim 1, wherein the semiconductor laser diode device is a high-power and high-reliability semiconductor laser diode device in a single mode and has a mesa wave guide structure.

5. The semiconductor laser diode device of claim 1, wherein the first upper clad layer, the second upper clad layer, and the second upper clad regrowth layer are doped at 1E+18 cm.sup.−3 or more by using carbon, magnesium (Mg), beryllium (Be) or zinc as a dopant.

6. The semiconductor laser diode device of claim 1, wherein the substrate and the lower clad layer are doped at 1E+18 cm.sup.−3 or more by using silicon, tellurium (TE) or selenium (SE) as a dopant.

7. The semiconductor laser diode device of claim 1, wherein the anti-oxidation layer is thinly formed at a thickness of 100 Å or less between the second upper clad layer and the second upper clad regrowth layer to be grown without affecting a mode due to a refractive index.

8. The semiconductor laser diode device of claim 1, wherein the active layer includes AlGaAs double quantum well (DQW) and is undoped.

9. The semiconductor laser diode device of claim 1, wherein the etch stop layer is selectively wet-etched with an Alx composition of 0.8 or more as AlGaAs.

10. The semiconductor laser diode device of claim 1, wherein the semiconductor laser diode device has a selective buried ridge structure of growing the current blocking layer, the second upper clad regrowth layer, and the contact layer with MOCVD after constituting the wave guide.

11. The semiconductor laser diode device of claim 2, wherein the second upper clad layer is thinly grown on ESL at 1 μm or less, and the second upper clad regrowth layer is grown on the anti-oxidation layer and the current blocking layer at 0.5 μm or less and an error of a growth thickness is within ±10%.

12. The semiconductor laser diode device of claim 2, wherein a width of a lower wave guide is narrowed to 2.0 to 4.0 and a width of a upper wave guide is 1.5 μm or more.

13. A manufacturing method of a semiconductor laser diode device with high power and high reliability comprising: a primary growth step of forming a lower clad layer on a semiconductor substrate, forming an active layer on the lower clad layer, forming a first upper clad layer on the active layer, forming an etch stop layer on the first upper clad layer, forming a second upper clad layer on the etch stop layer, and forming an anti-oxidation layer on the second upper clad layer; a secondary growth step of forming a mesa-shaped wave guide by preparing and disposing a wave guide mask on a wafer in which a primary growth is completed using a dielectric film and etching the anti-oxidation layer and the second upper clad layer through wet etching, and selectively growing a current blocking layer on a side surface of the wave guide using metal organic chemical vapor deposition (MOCVD) through a dielectric film mask; and a tertiary growth step of removing the wave guide mask and growing a second upper clad regrowth layer to compensate for a thickness of the second upper clad layer grown in the primary growth, continuously growing a contact layer on the second upper clad regrowth layer, and depositing p and n-type metals to form an electrode.

14. A semiconductor laser diode device module comprising a lower clad, an active layer, and an upper clad in sequence, wherein the upper clad comprises a first upper clad layer; a second upper clad layer formed in a mesa structure on an etch stop layer formed on the first upper clad layer; and an anti-oxidation layer formed in a mesa structure on the second upper clad layer and a second upper clad regrowth layer formed on a current blocking layer formed on a side surface of the mesa structure to compensate from a thickness of the second upper clad layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0031] FIG. 1 is a schematic diagram of a high-power and high-reliability semiconductor laser diode according to a second upper clad (P clad) regrowth method of the present disclosure;

[0032] FIG. 2 is a schematic diagram of a laser diode according to the related art (only second upper clad+wet etching);

[0033] FIGS. 3A through 3F are illustrating a fabrication process of manufacturing a high-power and high-reliability laser diode applied with a second upper clad (P clad) regrowth method of the present disclosure;

[0034] FIG. 4 is graphs showing a voltage and a resistance at room temperature according to the present disclosure;

[0035] FIG. 5A is a graph showing Kink and power at room temperature according to the prior art;

[0036] FIG. 5B is a graph showing Kink and power at room temperature according to the present disclosure;

[0037] FIG. 6A is a graph showing reliability at a high temperature according to the present disclosure;

[0038] FIG. 6B is a graph showing reliability at a high temperature according to the present disclosure; and

[0039] FIG. 7A is a graph showing characteristics of a beam according to the prior art.

[0040] FIG. 7B is a graph showing characteristics of a beam in the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0041] Hereinafter, a preferred embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0042] FIG. 1 is a cross-sectional view of a schematic diagram of improving a high-power and high-reliability device of which a second upper clad is thick through the second upper clad (P clad) regrowth according to an embodiment of the present disclosure. The high-power and high-reliability device consists of a lower clad layer 2, an active layer 3, a first upper clad layer 4, an etch stop layer 5, a second upper clad layer 6, and an anti-oxidation layer 7 on a compound semiconductor substrate 1 in sequence.

[0043] When describing a material and a growth order of primary growth of the high-power and high-reliability laser diode in detail, the substrate 1 consists of an n-type GaAs compound semiconductor. In this case, the lower clad layer 2 consists of n-type AlxGaAs (Alx composition is 0.5 to 0.6) and the doping of the lower clad layer 2 is performed at a concentration of 1E-18 cm.sup.2. A dopant of the lower clad layer 2 uses silicon. In addition, tellurium (TE) and selenium (SE) dopants may be used.

[0044] The active layer 3 consists of an AlxGaAs double quantum well (DQW) and is undoped. Two quantum wells were used to increase the number of carriers. In order to prevent carrier overflow and current leakage and control an FFV mode, the active layer 3 is constituted in a double barrier separate confinement heterostructure (DBSCH) of adding a barrier between the active layer and the clad.

[0045] The first upper clad layer 4 consists of p-type AlxGaAs (Alx composition is 0.4 to 0.6) and doped at 1E+18 cm′ or more. A dopant of the first upper clad layer 4 uses carbon, zinc, magnesium (Mg), or beryllium (Be).

[0046] The etch stop layer 5 for making the wave guide enables selective wet etching using a material with a high Alx composition as AlxGaAs. In addition, finally, GaAs is thinly formed at 1.0E+18 cm′ or more by doping at 1 μm so as not to affect a refractive index of the second upper clad (P clad) regrowth layer while preventing the Alx oxidation of the primary growth. In this order, the primary growth is completed.

[0047] The following is an order of a fabricating process of the high-power and high-reliability laser diode.

[0048] A wave guide mask is prepared on a wafer in which the primary growth is completed using a dielectric film (SiOx, SiNx) and the anti-oxidation layer 7 and the second upper clad layer 6 are etched through wet etching to form a mesa-shaped wave guide 8. As current blocking layer 9, p-type AlxGaAs (Alx composition is 0.6 to 0.7) is selectively grown on the side surface of the wave guide using metal organic chemical vapor deposition (MOCVD) through a dielectric film mask and doped at 1E+18 cm′ or more. In order to remove the wave guide mask and compensate for the second upper clad layer thinly grown in the primary growth, as a second upper clad regrowth layer 10, p-type AlxGaAs (Alx composition is 0.5 to 0.6) is grown and doped at 1.5E+19 cm.sup.−3 or more. Subsequently, p-type GaAs as a contact layer 11 is grown on the second upper clad regrowth layer 10 and doped at 1.5E+19 cm.sup.−3 or more. Finally, p and n-type metals are deposited to form an electrode.

[0049] There is an advantage of improving the performance of the laser by minimizing the internal resistance and the heat loss of the high-reliability laser diode through the EPI structure and the FAB process technique.

[0050] That is, according to the present disclosure, in a semiconductor laser diode device module including the lower clad, the active layer, and the upper clad in sequence, the structure of the upper clad was newly designed. The upper clad layer consists of two first and second layers, but the second upper clad layer forming the mesa structure is thinly formed to form a mesa structure having a relatively gentle tapered shape even though forming the wave guide of the mesa structure by wet etching, and the small thickness of the second upper clad layer is compensated by thinly forming the regrowth layer of the second upper clad layer on the wave guide with the mesa structure.

[0051] The high-power and high-reliability laser diode fabricated according to the embodiment of the present disclosure obtained the results illustrated in FIGS. 4 to 7.

[0052] That is, as compared with the related art, it can be confirmed that the driving voltage and resistance of the laser diode device of the present disclosure are lowered as illustrated in FIG. 4, and it was shown that the laser diode device may reach high reliability having higher power and longer life (FIGS. 5B, 6A and 6B).

[0053] In addition, in the related art, a distortion phenomenon of the beam generated by the asymmetry of the wave guide may be improved by the present disclosure (FIGS. 7A and 7B).

[0054] Further, as compared with the related art (only second upper clad+dry etching+wet etching), in the present disclosure (second upper clad regrowth+wet etching), only the wet etching is applied once to reduce the number of etching times and many wafers may be performed at the same time to improve productivity.

[0055] The scope of the present disclosure is not limited to the AlGaAs series described above and can be applied even to InGaAlP series. That is, even in the design of the second upper clad and the wave guide design control of the InGaAlP-based laser diode device, when the second upper clad regrowth process is introduced in the same manner as described above, the resistance and the voltage are improved during the operation, and the Kink and the COD power are increased to fabricate a high-power and high-reliability laser diode device. The InGaAlP-based laser diode device includes a lower clad InGaAlP, an active layer InGaP, and an upper clad InGaAlP.

[0056] It will be apparent that the scope of the present disclosure is not limited to the embodiments described above and defined by those disclosed in the appended claims, and those skilled in the art can make various modification and changes within the scope disclosed in the appended claims.