JP2013110207A - Semiconductor optical integrated element and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor optical integrated element and a manufacturing method of the same, which reduce a dark current of a PD to 10 nA and under without increasing a propagation loss of an optical waveguide.SOLUTION: A semiconductor optical integrated element manufacturing method comprises: doping Fe of a concentration equal to or lower than a saturating concentration in a (100) plane orientation, to an optical waveguide layer in an optical waveguide region butt joint bonded in a [011] direction with an inclined lateral face of the photodiode region in which at least a light absorption layer and a Zn-doped p-type clad layer are sequentially laminated from an n-type clad layer side; and doping Fe of a concentration equal to or higher than a saturating concentration in a (100) plane orientation to an upper clad layer.

Description

  The present invention relates to a semiconductor optical integrated device and a method for manufacturing the same, and relates to, for example, reduction of dark current in a waveguide type PD in which a photodiode (PD) and an optical waveguide are monolithically integrated by butt joint coupling.

  With the increase in speed and capacity of optical communication systems, miniaturization and low power consumption of optical components constituting a network are required. A waveguide type PD in which an optical waveguide for guiding an optical signal and a PD for receiving an optical signal are monolithically integrated is one of semiconductor optical integrated elements required for miniaturization of optical components (for example, see Patent Document 1). ).

  FIG. 8 is a conceptual cross-sectional view of a conventional waveguide type PD formed by butt joint coupling. First, an n-type InP cladding layer 72, a non-doped i-type InGaAs light absorption layer 73, a Zn-doped p-type InP cladding layer 74, and a Zn-doped p-type InGaAs on an InP substrate 71 having a (100) plane as a main surface. A contact layer 75 is grown.

Next, a SiO ₂ mask is applied to the PD formation region, and a region not covered with the SiO ₂ mask is removed to the i-type InGaAs light absorption layer 73 by wet etching to form a PD region. At this time, a flat (100) surface is formed in the optical waveguide region, and a side surface inclined with respect to the (100) surface is formed in the side surface of the PD region.

Next, using the SiO ₂ mask as a selective growth mask, the undoped i-type InGaAsP optical waveguide layer 76 and the undoped i-type InP cladding layer 77 are regrown to form an optical waveguide region. At this time, the i-type InGaAsP optical waveguide layer 76 is thinly raised on the side surface of the PD region. In addition, the code | symbols 78 and 79 in a figure are an n side electrode and a p side electrode, respectively.

JP 2002-217446 A Japanese Patent Laid-Open No. 06-324226

Journal of Crystal Growth, Vol. 124, pp. 352-357, 1992

  However, when the present inventors applied the above-described conventional technology to produce a waveguide type PD, the dark current flowing through the regrowth interface, which is the junction between the PD region and the optical waveguide region, is large (> 100 nA @ -5V). ).

As a result of intensive studies by the present inventors, as shown in FIG. 9, impurity segregation derived from an environmental atmosphere such as Si or O having a concentration of 10 ¹⁷ cm ⁻³ to 10 ¹⁸ cm ^{−3 on the} regrowth interface formed by etching. Has ceased to exist. It is presumed that the dark current is caused by the n-type layer 80 remaining due to the segregation of impurities at the regrowth interface.

  Therefore, by utilizing the property that Fe and Zn are easily diffused, an attempt was made to induce Zn diffusion from the PD region to the waveguide region and to compensate the n-shift layer at the regrowth interface with Zn. In the waveguide type optical integrated device, there is an example in which the regrown InGaAsP optical waveguide layer or the InP upper cladding layer is doped with Fe (for example, see Patent Document 2). However, since there is no description about Fe concentration, generally Fe concentration is below a saturation concentration.

The saturated concentration is a solid solution limit concentration that can be electrically activated (formation of deep acceptor levels) by substituting Fe atoms with group III lattice positions. According to the above non-patent document 1,
Fe saturation concentration in (100) plane orientation InP: ˜5 × 10 ¹⁶ cm ⁻³
Fe saturation concentration in (100) plane orientation InGaAsP: ˜4 × 10 ¹⁶ cm ⁻³
It is. Non-Patent Document 1 describes that when the InGaAsP layer is highly doped with Fe, the growth surface tends to be rough.

  Therefore, when the Fe-doped InGaAsP layer is applied to the optical waveguide layer, the concentration of Fe doped in the InGaAsP optical waveguide layer must be less than the saturation concentration in order to prevent an increase in light propagation loss due to surface roughness. I came to a conclusion.

Therefore, the inventor of the present invention has an optical waveguide layer and an upper cladding layer, each of which is an InGaAsP optical waveguide layer doped with 3 × 10 ¹⁶ cm ⁻³ in (100) plane orientation and 5 × 10 ¹⁶ in (100) plane orientation. A waveguide type PD was fabricated by substituting the Fe- ³ doped InP cladding layer with cm ⁻³ .

  However, although the dark current was reduced to several tens of nA @ -5V, the effect of compensating the n-shift region on the side surface of the PD region was not sufficient, and the dark current could not be suppressed to nA order or less.

  Therefore, an object of the present invention is to reduce the dark current of the PD to 10 nA or less without increasing the propagation loss of the optical waveguide.

  From one aspect disclosed, a photodiode region having a side surface inclined with respect to a (100) plane, which is formed on a (100) plane semiconductor substrate via an n-type cladding layer, A semiconductor optical integrated device comprising a group III-V compound semiconductor having an optical waveguide region butt-jointed in the [011] direction with respect to the side surface of the photodiode region, wherein the photodiode region comprises the n-type cladding At least a light absorption layer and a Zn-doped p-type cladding layer laminated in order from the n-type cladding layer side, and the optical waveguide region is arranged on the n-type cladding layer in order from the n-type cladding layer side. The optical waveguide layer has at least a laminated optical waveguide layer and an upper cladding layer, and the optical waveguide layer has a rising portion with respect to the inclined side surface. e is doped to a saturation concentration in the (100) plane orientation or less, and Fe is doped in the upper cladding layer to a saturation concentration in the (100) plane orientation or more. An element is provided.

  From another viewpoint to be disclosed, an n-type cladding layer, a light absorption layer, and a Zn-doped p-type cladding layer are sequentially formed from the semiconductor substrate side on a semiconductor substrate having a (100) plane orientation of the main surface. A step of growing at least; a step of removing a part of the Zn-doped p-type cladding layer or the light absorption layer to form a photodiode region having a side surface inclined with respect to the (100) plane in the [011] direction; The removal portion of the Zn-doped p-type cladding layer to the light absorption layer is doped with a non-doped optical waveguide layer having a rising portion with respect to the inclined side surface, and Fe is more than a saturated concentration in the (100) plane orientation And a step of sequentially growing the upper cladding layer. A method for manufacturing a semiconductor optical integrated device is provided.

  According to the disclosed semiconductor optical integrated device and the manufacturing method thereof, the dark current of the PD can be reduced without increasing the propagation loss of the optical waveguide.

1 is a conceptual cross-sectional view of a semiconductor optical integrated device according to an embodiment of the present invention. It is explanatory drawing of the manufacturing process to the middle of waveguide type PD of Example 1 of this invention. It is explanatory drawing of the manufacturing process to the middle after FIG. 2 of waveguide type PD of Example 1 of this invention. It is explanatory drawing of the manufacturing process after FIG. 3 of waveguide type PD of Example 1 of this invention. It is explanatory drawing of the manufacturing process to the middle of the semiconductor optical integrated circuit device provided with waveguide type PD of Example 3 of this invention. It is explanatory drawing of the manufacturing process to the middle after FIG. 5 of the semiconductor optical integrated circuit device provided with waveguide type PD of Example 3 of this invention. It is explanatory drawing of the manufacturing process to the middle after FIG. 6 of the semiconductor optical integrated circuit device provided with waveguide type PD of Example 3 of this invention. It is a conceptual sectional view of the conventional waveguide type PD formed by butt joint coupling. It is explanatory drawing of the n rolling layer generate | occur | produced in the conventional butt joint interface.

  Here, a semiconductor optical integrated device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a conceptual cross-sectional view of a semiconductor optical integrated device according to an embodiment of the present invention. An n-type cladding layer 12, a light absorption layer 13, a Zn-doped p-type cladding layer 14 and a Zn-doped p-type contact layer 15 are sequentially grown on a semiconductor substrate 11 having a (100) plane as a main surface. The Zn-doped p-type contact layer 15 is not essential.

Next, a SiO ₂ mask is formed in the PD formation region, a region not covered with the SiO ₂ mask is removed by wet etching, and a photodiode region 16 having a side surface inclined with respect to the (100) plane in the [011] orientation. Form. Next, using the SiO ₂ mask as a selective growth mask, the non-doped optical waveguide layer 17 and the upper cladding layer 18 doped with Fe at a saturation concentration or higher in the (100) plane orientation are grown in the etching removal portion, and the [011] direction The optical waveguide region 19 is butt-joined to the optical waveguide region 19. At this time, Fe is solid-phase diffused from the upper cladding layer 18 into the non-doped optical waveguide layer 17, but the average concentration of Fe in the optical waveguide layer 17 is equal to or lower than the saturation concentration in the (100) plane orientation. Reference numerals 20 and 21 in the figure denote an n-side electrode and a p-side electrode, respectively.

More preferably, an Fe-doped buffer layer made of the same III-V group material as that of the n-type cladding layer 12 is desirably laminated below the optical waveguide layer 17, and the thickness of the Fe-doped buffer layer is
It is desirable to satisfy the relationship of Fe-doped buffer layer thickness + optical waveguide layer 17 thickness ≦ light absorption layer 13 thickness.

  These material compositions are such that when used for 1.55 μm band or 1.3 μm band optical communication, the semiconductor substrate 11, the n-type cladding layer 12, the Zn-doped p-type cladding layer 14 and the upper cladding layer 18 are made of InP. And The light absorption layer 13 may be InGaAs, the optical waveguide layer 17 may be InGaAsP, and the Zn-doped p-type contact layer 15 may be InGaAs or InGaAsP.

  In the embodiment of the present invention, since the Fe doping amount of the optical waveguide layer 17 is equal to or lower than the saturation concentration, the growth surface of the optical waveguide layer 17 is obtained without being roughened, and thereby the propagation of the waveguide. Loss increases are avoided. Even if the upper cladding layer 18 is doped with Fe to a saturation concentration or more, the surface is not roughened and the propagation loss of the optical waveguide is not increased.

  Further, by making the Fe doping amount of the upper cladding layer 18 equal to or higher than the saturation concentration, Fe atoms that are not taken into the group III lattice position are likely to move, so that the upper cladding layer 18 and the Zn-doped p-type layer (14 15), interdiffusion of Fe and Zn is likely to occur.

  As a result, Zn diffusion from the PD region 16 to the waveguide region 19 is further induced even when the rising portion of the optical waveguide layer 17 is interposed, and the n-shift layer at the regrowth interface on the PD side surface is compensated with Zn. . Thereby, the dark current through the PD side surface can be reduced to nA order or less.

  When the Fe-doped buffer layer is regrown before the optical waveguide layer 17 is regrown, the quality of the regrown optical waveguide layer 17 is improved by the effect of the buffer layer. The optical waveguide layer 17 is not limited to non-doped growth, and may be doped with Fe as long as the concentration is less than the saturation concentration even when the diffusion amount of Fe from the upper cladding layer 18 is expected.

Next, with reference to FIGS. 2 to 4, a manufacturing process of the waveguide type PD according to the first embodiment of the present invention will be described. The crystal growth is performed by, for example, a metal organic vapor phase growth method. First, as shown in FIG. 2A, an n-type InP cladding layer 32 having a thickness of 1 μm and an undoped i-type layer having a thickness of 0.4 μm are formed on an n-type InP substrate 31 having a (100) plane as a main surface. A type InGaAs light absorption layer 33 is grown. Subsequently, a p-type InP cladding layer 34 having a thickness of 1 μm and a p-type InGaAs contact layer 35 having a thickness of 0.3 μm are sequentially grown to form a PD structure. At this time, the Zn concentration of the p-type InP cladding layer 34 is 1 × 10 ¹⁸ cm ^−3, and the Zn concentration of the p-type InGaAs contact layer 35 is 1 × 10 ¹⁹ cm ⁻³ .

Next, as shown in FIG. 2B, a SiO ₂ mask 36 having a thickness of 0.5 μm is formed in the PD formation region. Next, as shown in FIG. 2C, the SiO ₂ mask 36 is used as a mask. The p-type InGaAs contact layer 35 is selectively etched with a sulfuric acid-based solution. Next, the p-type InP cladding layer 34 is selectively etched with HBr, and then the i-type InGaAs light absorption layer 33 is etched with a sulfuric acid-based solution to etch away the PD structure in the optical waveguide region. At this time, an etching surface inclined with respect to the (100) plane is formed on the side surface of the PD region.

Next, as shown in FIG. 3D, a non-doped InGaAsP optical waveguide layer 37 having a thickness of 0.3 μm and a composition wavelength of 1.3 μm is grown using the SiO ₂ mask 36 as a selective growth mask. Subsequently, an InP upper cladding layer 38 having a thickness of 1.1 μm and doped with Fe of a saturation concentration or more is regrown. As a result, a structure in which the InGaAsP optical waveguide layer 37 and the i-type InGaAs light absorption layer 33 are butt-jointed in the [011] direction is formed. If the Fe concentration of the InP upper cladding layer 38 at this time is 2 × 10 ¹⁷ cm ⁻³ which is equal to or higher than the saturation concentration in the (100) plane, Fe diffuses into the InGaAsP optical waveguide layer 37, and the Fe concentration in the InGaAsP optical waveguide layer 37 Becomes 3 × 10 ¹⁶ cm ^{−3 which} is equal to or lower than the saturation concentration on the (100) plane. In this regrowth process, the InGaAsP layer 39 grows slightly on the inclined side surface of the PD region.

Next, as shown in FIGS. 3E and 3F, after removing the SiO ₂ mask 36, the thickness is newly 0.5 μm, the width in the optical waveguide region is 2.0 μm, and the width in the PD region is A 10 μm striped SiO ₂ mask 40 is formed. Next, a stripe mesa having a height of 2 μm is formed by ICP-RIE (inductively coupled reactive ion etching) using the SiO ₂ mask 40 as a mask. FIG. 3F is a plan view.

Next, as shown in FIG. 4G, using the SiO ₂ mask 40 as a selective growth mask, both sides of the stripe mesa are buried with an Fe-doped InP layer 41 having an Fe concentration of 5 × 10 ¹⁶ cm ⁻³ , and the width of the PD region The direction side surface is protected by the Fe-doped InP layer 41.

Next, as shown in FIG. 4H, after the SiO ₂ mask 40 is removed, a new SiO ₂ film 42 is formed. Next, after forming an opening in the SiO ₂ film 42 in the PD region, Ti, Pt, and Au are sequentially deposited to form the p-side electrode 43. Further, by sequentially depositing AuGe and Au on the back surface of the n-type InP substrate 31 to form the n-side electrode 44, the waveguide type PD of Example 1 of the present invention is completed.

  As a result of measuring the dark current of this waveguide type PD, a low value of 2 nA @ -5V and nA order was obtained. In addition, the propagation loss in the waveguide region was 0.15 dB / mm, which was a satisfactory level. As described above, in Example 1 of the present invention, since the upper cladding layer is doped with Fe having a saturation concentration or more, the diffusion of Zn from the PD region is induced to suppress the occurrence of the n-type layer. Therefore, the dark current can be on the order of nA. In addition, since the Fe concentration of the optical waveguide layer is set to the saturation concentration or less, the growth surface is less rough and propagation loss in the waveguide region can be reduced.

Next, although the manufacturing process of waveguide type PD of Example 2 of this invention is demonstrated, since a basic process is the same as said Example 1, only a different point is demonstrated. In Example 2 of the present invention, in the above-described step of FIG. 3D, instead of the non-doped InGaAsP optical waveguide layer, the Fe concentration is equal to or lower than the saturation concentration, for example, 3 × 10 ¹⁶ cm ^−3. Then, an InGaAsP optical waveguide layer intentionally doped with Fe is grown.

  As described above, in Example 2 of the present invention, since the optical waveguide layer is intentionally doped with Fe, generation of the n-layer can be more effectively suppressed. Further, since the Fe concentration is equal to or lower than the saturation concentration, the roughness of the growth surface does not become so large.

Next, a basic manufacturing process of the semiconductor optical integrated circuit device including the waveguide type PD according to the third embodiment of the present invention will be described with reference to FIGS. First, as shown in FIG. 5A, an n-type InP clad layer 52 having a thickness of 1 μm and a thickness of 0.4 μm are formed on a Fe-doped high-resistance InP substrate 51 having a (100) plane as a main surface. A non-doped i-type InGaAs light absorption layer 53 is grown. Subsequently, a PD structure is formed by sequentially growing a p-type InP cladding layer 54 having a thickness of 1 μm and a p-type InGaAs contact layer 55 having a thickness of 0.3 μm. At this time, the Zn concentration of the p-type InP cladding layer 54 is 1 × 10 ¹⁸ cm ^−3, and the Zn concentration of the p-type InGaAs contact layer 55 is 1 × 10 ¹⁹ cm ⁻³ .

Next, as shown in FIG. 5B, a SiO ₂ mask 56 having a thickness of 0.5 μm is formed in the PD formation region. Next, as shown in FIG. 5C, the SiO ₂ mask 56 is used as a mask. The p-type InGaAs contact layer 55 is selectively etched with a sulfuric acid-based solution. Next, the p-type InP cladding layer 54 is selectively etched with HBr, and then the i-type InGaAs light absorption layer 53 is etched with a sulfuric acid-based solution to etch away the PD structure in the optical waveguide region. At this time, an etching surface inclined with respect to the (100) plane is formed on the side surface of the PD region.

Next, as shown in FIG. 6D, an Fe-doped InP buffer layer 57 having a thickness of 0.1 μm is grown using the SiO ₂ mask 56 as a selective growth mask. At this time, the Fe concentration is set to 1 × 10 ¹⁷ cm ⁻³ which is equal to or higher than the saturation concentration. Subsequently, an Fe-doped InGaAsP optical waveguide layer 58 having a thickness of 0.3 μm and a composition wavelength of 1.3 μm and an Fe-doped InP upper cladding layer 59 having a thickness of 1 μm and a saturation concentration or more are regrown. As a result, a structure in which the InGaAsP optical waveguide layer 58 and the i-type InGaAs light absorption layer 53 are butt-jointed in the [011] direction is formed. At this time, the Fe concentration of the InGaAsP optical waveguide layer 58 is 3 × 10 ¹⁶ cm ^{−3 which} is equal to or less than the saturation concentration in the (100) plane, and the Fe concentration of the InP upper cladding layer 59 is 2 × which is equal to or higher than the saturation concentration in the (100) plane. It is 10 ¹⁷ cm ⁻³ . In this regrowth process, the InGaAsP layer 60 grows slightly on the inclined side surface of the PD region.

Next, as shown in FIGS. 6E and 6F, after removing the SiO ₂ mask 56, the thickness is newly 0.5 μm, the width in the optical waveguide region is 2.0 μm, and the width in the PD region is A 10 μm striped SiO ₂ mask 61 is formed. Next, a stripe mesa having a height of 2 μm is formed by ICP-RIE using the SiO ₂ mask 61 as a mask. FIG. 6F is a plan view.

Next, as shown in FIG. 7G, a stripe-like SiO ₂ mask 62 along the stripe mesa is formed on the bottom surface of the mesa. Next, using the SiO ₂ mask 40 and the SiO ₂ mask 62 as selective growth masks, both sides of the stripe mesa are filled with an Fe-doped InP layer 63 with an Fe concentration of 5 × 10 ¹⁶ cm ⁻³ , and the side surface in the width direction of the PD region is Fe The doped InP layer 63 protects.

Next, as shown in FIG. 7H, after the SiO ₂ mask 40 and the SiO ₂ mask 62 are removed, a new SiO ₂ film 64 is formed. Next, an opening 65 for the p-side electrode and an opening 66 for the n-side electrode are formed in the SiO ₂ film 64 in the PD region.

  Next, as shown in FIG. 7 (i), Ti, Pt, and Au are sequentially deposited in the opening 65 to form the p-side electrode 67, and AuGe and Au are sequentially deposited in the opening 66 to form the n-side electrode. 68 is formed. In this way, the basic structure of the semiconductor optical integrated circuit device according to the third embodiment of the present invention having a coplanar structure electrode is completed. Although not shown, other optical devices such as a semiconductor laser and a semiconductor optical amplifier are monolithically formed on the high resistance InP substrate 51.

  In Embodiment 3 of the present invention, since the Fe-doped InP buffer layer 57 is grown before the InGaAsP optical waveguide layer 58 is regrown, the crystal quality of the InGaAsP optical waveguide layer 58 is improved and propagation in the waveguide region is improved. The loss was reduced to 0.1 dB / mm. Further, since the Fe-doped InP buffer layer 57 having a saturation concentration or higher is grown as the first layer, the effect of inducing Zn diffusion from the PD region is large, and the PD dark current is as low as 0.5 nA @ -5V. Obtained.

  Further, the sum of the thicknesses of the Fe-doped InP buffer layer 57 and the InGaAsP optical waveguide layer 58 serving as the core layer is 0.4 μm, which is the same as the thickness of the InGaAs light absorption layer 53. The PD absorption efficiency was not changed.

  As described above, each embodiment of the present invention has been described. However, the present invention is not limited to the described conditions, and various modifications are possible. For example, also in the above-described Embodiment 1 or Embodiment 2, the n-type InP cladding is used. An n-side electrode may be formed in the layer to form a coplanar structure.

  Further, as in the first embodiment or the second embodiment, even when a conductive substrate is used, an Fe-doped InP buffer layer may be interposed. Or, conversely, in Example 3, the InGaAsP optical waveguide layer may be directly grown without interposing the Fe-doped InP buffer layer. Furthermore, the Fe-doped InP buffer layer may be replaced with a non-doped InP buffer layer.

Here, the following supplementary notes are attached to the embodiments of the present invention including Examples 1 to 3.
(Appendix 1)
A photodiode region having a side surface inclined in the [011] direction formed on an (100) plane semiconductor substrate with an n-type cladding layer on the main surface;
A semiconductor optical integrated device comprising a group III-V compound semiconductor having an optical waveguide region butt-joint coupled to the side surface of the photodiode region,
The photodiode region has at least a light absorption layer and a Zn-doped p-type cladding layer stacked in order from the n-type cladding layer side on the n-type cladding layer,
The optical waveguide region has at least an optical waveguide layer and an upper cladding layer laminated on the n-type cladding layer sequentially from the n-type cladding layer side;
The optical waveguide layer has a rising portion with respect to the inclined side surface, Fe is doped in the optical waveguide layer to a saturation concentration or less in a (100) plane orientation, and Fe ( 100) A semiconductor optical integrated device characterized by being doped to a saturation concentration or more in the plane orientation.
(Appendix 2)
2. The semiconductor optical integrated device according to appendix 1, wherein a Zn-doped p-type contact layer is provided on the Zn-doped p-type cladding layer.
(Appendix 3)
Under the optical waveguide layer, an Fe-doped buffer layer having the same III-V group composition as the n-type cladding layer is provided,
An interface between the Fe-doped buffer layer and the optical waveguide layer is located closer to the semiconductor substrate than an interface between the light absorption layer and the Zn-doped p-type cladding layer, and the optical waveguide layer and the upper cladding layer The semiconductor optical integrated device according to appendix 1 or appendix 2, wherein the interface is located on the side farther from the semiconductor substrate than the interface between the light absorption layer and the Zn-doped p-type cladding layer.
(Appendix 4)
4. The semiconductor optical integrated device according to appendix 3, wherein the sum of the thickness of the Fe-doped buffer layer and the thickness of the optical waveguide layer is equal to or smaller than the thickness of the light absorption layer.
(Appendix 5)
5. The semiconductor optical integrated device according to any one of appendix 1 to appendix 4, wherein the semiconductor substrate is a high-resistance semiconductor substrate.
(Appendix 6)
The semiconductor substrate, the n-type cladding layer, the Zn-doped p-type cladding layer, and the upper cladding layer are made of InP, the light absorption layer is made of InGaAs, and the optical waveguide layer is made of InGaAsP. 5. The semiconductor optical integrated device according to any one of 5 above.
(Appendix 7)
Growing at least an n-type cladding layer, a light absorption layer, and a Zn-doped p-type cladding layer in order from the semiconductor substrate side on a semiconductor substrate having a (100) plane orientation of the main surface;
Removing a part of the Zn-doped p-type cladding layer or the light absorption layer to form a photodiode region having a side surface inclined in the [011] direction;
In the removed portion of the Zn-doped p-type cladding layer or the light absorption layer, a non-doped optical waveguide layer having a rising portion with respect to the side surface inclined in the [011] direction, and Fe is saturated in the (100) plane orientation And a step of sequentially growing the upper clad layer doped as described above.
(Appendix 8)
Before the step of growing the optical waveguide layer,
An Fe-doped buffer layer having the same III-V group composition as the n-type cladding layer and having a rising portion with respect to the side surface inclined in the [011] direction at the removal portion of the Zn-doped p-type cladding layer or light absorption layer 8. The method for manufacturing a semiconductor optical integrated device according to appendix 7, wherein the method includes a step of growing a semiconductor.

11 Semiconductor substrate 12 n-type cladding layer 13 light absorption layer 14 Zn-doped p-type cladding layer 15 Zn-doped p-type contact layer 16 photodiode region 17 optical waveguide layer 18 upper cladding layer 19 optical waveguide region 20 n-side electrode 21 p-side electrode 31 n-type InP substrate 32, 52 n-type InP cladding layer 33, 53 i-type InGaAs light absorption layer 34, 54 p-type InP cladding layer 35, 55 p-type InGaAs contact layer 36, 56 SiO ₂ mask 37, 58 InGaAsP optical waveguide Layers 38, 59 InP upper cladding layer 39, 60 InGaAsP layer 40, 61 SiO ₂ mask 41, 63 Fe-doped InP layer 42, 64 SiO ₂ film 43, 67 p-side electrode 44, 68 n-side electrode 51 High resistance InP substrate 57 Fe-doped InP buffer layer 62 SiO ₂ mask 65, 6 opening 71 InP substrate 72 n-type InP cladding layer 73 i-type InGaAs light absorption layer 74 p-type InP cladding layer 75 p-type InGaAs contact layer 76 i-type InGaAsP optical waveguide layer 77 i-type InP cladding layer 78 n-side electrode 79 p Side electrode 80 n transition layer

Claims (5)

A photodiode region having a side surface inclined with respect to the (100) plane, formed on the semiconductor substrate having a principal plane of (100) plane via an n-type cladding layer;
A semiconductor optical integrated device comprising a group III-V compound semiconductor having an optical waveguide region butt-jointed in the [011] direction to the side surface of the photodiode region,
The photodiode region has at least a light absorption layer and a Zn-doped p-type cladding layer stacked in order from the n-type cladding layer side on the n-type cladding layer,
The optical waveguide region has at least an optical waveguide layer and an upper cladding layer laminated on the n-type cladding layer sequentially from the n-type cladding layer side;
The optical waveguide layer has a rising portion with respect to the inclined side surface, Fe is doped in the optical waveguide layer to a saturation concentration or less in a (100) plane orientation, and Fe ( 100) A semiconductor optical integrated device characterized by being doped to a saturation concentration or more in the plane orientation. Under the optical waveguide layer, an Fe-doped buffer layer having the same III-V group composition as the n-type cladding layer is provided,
An interface between the Fe-doped buffer layer and the optical waveguide layer is located closer to the semiconductor substrate than an interface between the light absorption layer and the Zn-doped p-type cladding layer, and the optical waveguide layer and the upper cladding layer 2. The semiconductor optical integrated device according to claim 1, wherein the interface is located on a side farther from the semiconductor substrate than the interface between the light absorption layer and the Zn-doped p-type cladding layer.   3. The semiconductor optical integrated device according to claim 1, wherein the semiconductor substrate is a high resistance semiconductor substrate.   The semiconductor substrate, the n-type cladding layer, the Zn-doped p-type cladding layer, and the upper cladding layer are made of InP, the light absorption layer is made of InGaAs, and the optical waveguide layer is made of InGaAsP. The semiconductor optical integrated device according to any one of claims 1 to 3. Growing at least an n-type cladding layer, a light absorption layer, and a Zn-doped p-type cladding layer in order from the semiconductor substrate side on a semiconductor substrate having a (100) plane orientation of the main surface;
Removing a part of the Zn-doped p-type cladding layer or the light absorption layer to form a photodiode region having a side surface inclined with respect to the (100) plane in the [011] direction;
The removal portion of the Zn-doped p-type cladding layer or the light absorption layer is doped with a non-doped optical waveguide layer having a rising portion with respect to the inclined side surface, and Fe more than a saturated concentration in the (100) plane orientation And a step of sequentially growing the upper clad layer.

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