JP2012019040A - Surface emitting laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface emitting laser which has high reliability and a current constriction layer having a compound including Al and its oxide insulator.SOLUTION: A current path restriction layer restricts a current path for current flowing between an electrode 121 and an electrode 131, and pseudo composition graded layers 109, 111 are provided at both sides of a current constriction layer 110 having a current injection part 110a and a current constriction part 110b. Pseudo composition graded layers 109, 111 are formed by a plurality of semiconductor layers 171 to 175, each layer of semiconductor layers 171 to 175 is formed by GaAs layers 171a to 175a and AlGaAs layers 171b to 175b respectively. Film thickness ratios of GaAs layers 171a to 175a and of AlGaAs layers 171b to 175b are changed, thereby pseudo composition graded layers 109, 111 are configured such that the average Al composition changes.

Description

  The present invention relates to a surface emitting laser, and more particularly to a surface emitting laser including a current confinement layer that constricts a current path injected from an electrode.

  The current confinement layer includes an oxide insulator layer obtained by oxidizing a compound semiconductor containing aluminum such as AlAs, and a compound semiconductor containing aluminum such as AlAs in which current (carriers) is concentrated by the oxide insulator layer. And an opening.

  In such a semiconductor laser element, from the viewpoint of current injection efficiency, a composition gradient layer made of AlGaAs in which the composition ratio of aluminum gradually decreases as the distance from the surface in contact with the current confinement layer is increased on both sides of the current confinement layer. Proposed to provide.

For example, Patent Document 1 discloses an AlGaAs composition gradient in which the composition of aluminum is continuously changed on both sides of a layer made of AlAs up to Al _0.15 Ga _0.85 As which is a material of an AlAs resonator spacer layer. A surface emitting laser element provided with a layer is described.

JP 2002-359434 A

  The inventors of the present invention have produced a semiconductor laser device having AlGaAs composition graded layers on both sides of the current confinement layer by using such a technique. However, such an element includes an oxidation region of the current confinement layer and an AlGaAs composition graded layer. If the oxide region near the interface is poor in controllability, the layer is peeled off near the oxidized part in the device manufacturing stage and the yield is poor, and the current confinement layer is close to the active layer. The unevenness of the oxidation penetration depth at the interface between the surface and the non-oxidized layer occurs in the active layer and uniform characteristics cannot be obtained.In addition, dislocation due to strain occurs in the active layer, resulting in poor yield, or during manufacturing Even if there was no problem, we found a problem that the laser was not reliable when it was driven for a long time.

  A main object of the present invention is to provide a surface emitting laser including a current confinement layer having a compound containing Al and an oxide insulator thereof, which has improved yield and excellent reliability.

According to the present invention,
Formed on a III-V compound substrate;
A resonator region comprising an active layer and an Al-containing oxide constriction layer;
A surface emitting laser comprising a pair of DBR mirrors facing each other so as to sandwich the resonator region,
On both sides of the Al-containing oxide constriction layer, the Al-containing oxide constriction layer includes a plurality of steps including an Al-containing III-V group compound and an Al-free III-V group compound. A surface-emitting laser characterized in that a pseudo-composition gradient layer that continuously decreases as the distance from the oxidized constricting layer is formed, and a part thereof is oxidized from an interface adjacent to the Al-containing oxidized constricting layer. Provided.

Preferably, the Al-containing oxide constriction layer is Al _x Ga _1-x As (0.93 ≦ x <1).

Preferably, the Al-containing III-V group compound is Al _x Ga _1-x As (0.75 ≦ x ≦ 0.99), the Al-free III-V group compound is GaAs, and the Al-containing A pseudo composition gradient layer is formed by combining the steps of the pseudo composition by changing the film thickness of the III-V group compound and the Al-free III-V group compound so that the composition changes continuously. To do.

  Preferably, the Al-containing III-V group compound is AlAs, the Al-free III-V group compound is GaAs, and the film thickness of the Al-containing III-V compound and the Al-free III-V group compound. The pseudo gradient composition layer is formed by combining the steps in which the pseudo composition is formed by changing so that the composition changes continuously.

Preferably, the Al-containing III-V group compound is Al _x Ga _1-x As (0 ≦ x ≦ 0.99), the Al-free III-V group compound is GaAs, and the film thickness is constant. The step comprising the Al-containing III-V group compound having a different Al composition and the Al-non-containing III-V group compound having a film thickness of 0.1 to 0.5 nm is combined to change the composition continuously. A typical composition gradient layer is formed.

  Preferably, the Al composition interval in the step is small on the active layer side.

  Preferably, the Al composition gap between layers or adjacent layers is 0.5 or less.

  Preferably, the unevenness of the interface in the stacking direction of the composition gradient layer is 4 nm or less.

  Preferably, the unevenness of the interface in the stacking direction of the composition gradient layer is 2 nm or less.

  Preferably, the distance between the Al-containing oxidized constricting layer and the active layer falls within a range of 40 to 400 nm.

  Preferably, an In-containing layer is inserted between the Al-containing oxidized constricting layer and the active layer.

Moreover, according to the present invention,
Formed on a III-V compound substrate;
A resonator region comprising an active layer and an Al-containing oxide constriction layer;
A surface-emitting laser comprising a pair of DBR mirrors facing each other so as to sandwich the resonance region,
The DBR mirror is composed of a semiconductor mirror made of an AlGaAs / GaAs pair,
An Al-containing oxide constriction layer is formed on a part of the DBR mirror, and a plurality of steps comprising an Al-containing III-V compound and an Al-free III-V compound are provided on both sides of the Al-containing oxide constriction layer. The plurality of steps form a pseudo-composition gradient layer, the pseudo composition of which is continuously decreasing as the pseudo composition moves away from the Al-containing oxide constriction layer, and the Al-containing oxide There is provided a surface emitting laser characterized in that a part thereof is oxidized from an interface adjacent to the constriction layer.

  In addition, according to the present invention, a semiconductor laser element array including a plurality of any of the surface emitting lasers described above is provided.

  Moreover, according to this invention, an optical apparatus provided with one of the said surface emitting lasers is provided.

  Moreover, according to this invention, a communication system provided with one of the said surface emitting lasers is provided.

  According to the present invention, a semiconductor laser device (in particular, a surface emitting laser device) including a current confinement layer having a compound containing Al and an oxide insulator thereof, which has improved yield and excellent reliability, and a method for manufacturing the same Is provided.

It is a schematic longitudinal cross-sectional view for demonstrating the surface emitting semiconductor laser element of preferable 1st Embodiment of this invention. It is a partial expansion schematic longitudinal cross-sectional view of the A section of FIG. FIG. 3 is a partially enlarged schematic longitudinal sectional view for explaining a B part and a C part in FIG. 2. FIG. 2 is a partially enlarged schematic longitudinal sectional view of a portion corresponding to a portion A in FIG. 1 for describing the method for manufacturing the surface emitting semiconductor laser element according to the first preferred embodiment of the present invention. FIG. 3 is a partially enlarged schematic longitudinal sectional view of a portion corresponding to a portion B and a portion C in FIG. 2 for describing the method for manufacturing the surface-emitting type semiconductor laser device according to the first preferred embodiment of the present invention. FIG. 4 is a partially enlarged schematic longitudinal sectional view of a portion corresponding to a portion A in FIG. 1 for explaining a surface emitting semiconductor laser element according to a second preferred embodiment of the present invention. FIG. 7 is a partially enlarged schematic longitudinal sectional view for explaining a B part and a C part in FIG. 6. FIG. 10 is a partially enlarged schematic longitudinal sectional view of a portion corresponding to a portion B in FIG. 2 for illustrating a surface emitting semiconductor laser element according to a preferred third embodiment of the present invention. FIG. 10 is a partially enlarged schematic longitudinal sectional view of a portion corresponding to a portion B in FIG. 2 for illustrating a surface emitting semiconductor laser element according to a preferred fourth embodiment of the present invention. FIG. 3 is a partially enlarged schematic longitudinal sectional view of a portion corresponding to a portion B in FIG. 2 for describing a method for manufacturing a surface emitting semiconductor laser element of a comparative example. It is a figure which shows the relationship between the thermal shock test temperature and mesa destruction incidence rate of the surface emitting semiconductor laser element of preferable 1st Embodiment of this invention and a comparative example. It is a figure which shows the relationship between Al composition of AlGaAs and the oxidation rate of AlGaAs. 1 is a schematic perspective view for explaining a surface emitting laser array using a plurality of surface emitting semiconductor laser elements according to a preferred embodiment of the present invention. It is a schematic plan view for explaining a surface emitting laser array chip using a plurality of surface emitting semiconductor laser elements according to a preferred embodiment of the present invention. It is a schematic longitudinal cross-sectional view for demonstrating the surface emitting laser package using the surface emitting semiconductor laser element of preferable embodiment of this invention. It is a schematic longitudinal cross-sectional view for demonstrating the optical disk pick-up using the surface emitting type semiconductor laser element of preferable embodiment of this invention. It is a schematic plan view for demonstrating the optical transmission / reception module using the surface emitting semiconductor laser element of preferable embodiment of this invention. An optical coupling structure of a surface emitting semiconductor laser element and an optical waveguide according to a preferred embodiment of the present invention, or a surface emitting laser array and an optical waveguide using a plurality of surface emitting semiconductor laser elements according to a preferred embodiment of the present invention It is a schematic longitudinal cross-sectional view for demonstrating this optical coupling structure. An optical coupling structure of a surface emitting semiconductor laser element and an optical waveguide according to a preferred embodiment of the present invention, or a surface emitting laser array and an optical waveguide using a plurality of surface emitting semiconductor laser elements according to a preferred embodiment of the present invention It is a schematic longitudinal cross-sectional view for demonstrating this optical coupling structure. An optical coupling structure of a surface emitting semiconductor laser element and an optical waveguide according to a preferred embodiment of the present invention, or a surface emitting laser array and an optical waveguide using a plurality of surface emitting semiconductor laser elements according to a preferred embodiment of the present invention It is a schematic longitudinal cross-sectional view for demonstrating this optical coupling structure. A communication system using a surface emitting semiconductor laser element according to a preferred embodiment of the present invention or a communication system using a surface emitting laser array using a plurality of surface emitting semiconductor laser elements according to a preferred embodiment of the present invention will be described. It is a schematic block diagram for doing.

  Next, a vertical cavity surface emitting laser (VCSEL) according to a preferred embodiment of the present invention and a manufacturing method thereof will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments.

Referring to FIG. 1, a surface emitting laser 100 according to a preferred embodiment (first embodiment) of the present invention includes a substrate 101, a lower DBR 102, a buffer layer 103, n ⁺ -type contact layer 104, n-type spacer layer 105, active layer 106, first p-type spacer layer 108, lower pseudo composition gradient layer 109, current confinement layer 110, upper pseudo composition gradient layer 111, second The stacked structure includes a p-type spacer layer 112 and a p ⁺ -type contact layer 115. In the present embodiment, the buffer layer 103 to the p ⁺ -type contact layer 115 constitute a resonator including the resonator spacer layer, the current confinement layer 110, and the active layer 106.

Of the laminated structure, at least the n-type spacer layer 105 to the p ⁺ -type contact layer 112 constitute a cylindrical mesa post 130. The current confinement layer 110 includes a current confinement portion 110b located on the outer peripheral side of the mesa post 130 and a circular current injection portion 110a located inside the current confinement portion 110b. The diameter of the current injection part 110a is 6 μm, for example. The current confinement portion 110b restricts the path of the current flowing between the p-side annular electrode 121 and the n-side electrode 131, and the current flow is concentrated in the current injection portion 110a. It functions as a current path limiting layer.

The substrate 101 is made of undoped GaAs. The lower DBR 102 is composed of 34 pairs of GaAs / Al _0.9 Ga _0.1 As layers. The buffer layer 103 is made of n-type GaAs. The n ⁺ -type contact layer 104 is made of n ⁺ -type GaAs doped with an n-type dopant such as selenium (Se) or silicon (Si). The n-type spacer layer 105 is made of n-type GaAs doped with an n-type dopant. The active layer 106 has a multiple quantum well structure in which an InGaAs well layer having three layers and a GaAs barrier layer having four layers are alternately stacked. The uppermost layer and the lowermost layer are GaAs barrier layers. The lowermost GaAs barrier layer also functions as an n-type cladding layer.

The p-type spacer layers 108 and 112 and the p ⁺ -type contact layer 115 are made of p-type and p ⁺ -type GaAs doped with a p-type dopant such as carbon (C), zinc (Zn), or beryllium (Be), respectively. The acceptor or donor concentration of each p-type or n-type layer is, for example, about 1 × 10 ¹⁸ cm ⁻³ , and the acceptor or donor concentration of each p ⁺ -type or n ⁺ -type layer is, for example, 3 × 10 ¹⁹ cm ^−3. That's it.

A p-side annular electrode 121 is formed on the p ⁺ -type contact layer 115. The p-side annular electrode 121 is composed of a Pt / Ti layer (the lower side is the Ti layer 122 and the upper side is the Pt layer 123). The p-side annular electrode 121 has an opening 125 for allowing laser light to pass through in the center, and has an outer periphery that substantially coincides with the outer periphery of the cylindrical mesa post 130. The outer diameter of the p-side annular electrode 121 is, for example, 30 μm.

In the opening 125 of the p-side annular electrode 121, a disk-shaped dielectric layer 141 made of a material having low reactivity with Pt of the p-side annular electrode 121, here, silicon nitride (SiN _x ) is formed. Yes.

In the present embodiment, a dielectric layer 141 is formed on the p ⁺ -type contact layer 115 in the opening 125 of the p-side annular electrode 121. The dielectric layer 141 functions to adjust the optical length of the resonator and relax the step between the p-side annular electrode 121 and the opening. A portion from the upper surface of the dielectric layer 141 to the bottom surface of the buffer layer 103 constitutes the resonator 120.

An upper DBR 150 made of a dielectric multilayer film having a repeating structure of a pair of high refractive index and low refractive index layers is formed on the p-side annular electrode 121 and the dielectric layer 141 from the side of the mesa post 130 and the periphery thereof. Has been. The upper DBR 150 is made of, for example, 10 to 12 pairs of SiN _x / SiO ₂ . Further, a passivation film 145 made of SiO ₂ 143 and SiN _x 144 thereon is formed on the entire surface for surface protection. The SiO ₂ 143 and SiN _x 144 of the passivation film 145 can be stacked before the formation of the DBR mirror 150, so that the lowermost SiO ₂ and SiN _x of the DBR mirror 150 can be used together. In this case, the upper DBR mirror 150 made of SiN _x / SiO ₂ has the lowermost layer being SiO ₂ of the passivation film 145, and further has SiN _{x of the} passivation film 145, on which SiO ₂ and SiN are formed. _{In this structure, x} is alternately stacked, and the uppermost layer is SiN _x .

The n ⁺ -type contact layer 104 extends radially outward from the lower part of the mesa post 130, and is formed on the surface around the base of the mesa post 130 by, for example, AuGeNi / Au (the lower layer is AuGeNi and the upper layer is Au). An annular n-side electrode 131 is formed. For example, the n-side electrode 131 has an outer diameter of 90 μm and an inner diameter of 50 μm.

  On the n-side electrode 131, an n-side lead electrode (not shown) made of Au is formed, which is in contact with the n-side electrode 131 through an opening (not shown) formed in the passivation film 145. On the other hand, on the p-side annular electrode 121, a p-side extraction electrode (not shown) made of Au that contacts the p-side annular electrode 121 through an opening (not shown) formed in the passivation film 145. Is formed. Further, the n-side extraction electrode and the p-side extraction electrode connect the n-side electrode 131 and the p-side annular electrode 121 to a current supply circuit (not shown) provided outside, respectively.

In the surface emitting laser 100 having the above-described configuration, the n-side electrode 131 and the p-side circle are respectively connected from a current supply circuit (not shown) via an n-side extraction electrode (not shown) and a p-side extraction electrode (not shown). A voltage is applied between the annular electrodes 121, and a driving current is injected. The injected drive current mainly flows through the low resistance p ⁺ -type contact layer 115, and the current path is confined in the current injection part 110b by the current confinement layer 110, and is supplied to the active layer 106 at a high current density. The By this current injection, the active layer 106 emits spontaneous emission light. Of the spontaneous emission light, light having a wavelength λ which is a laser oscillation wavelength forms a standing wave in the resonator 120 between the lower DBR mirror 102 and the upper DBR mirror 150 and is amplified by the active layer 106. When the injection current exceeds the threshold value, the light that forms a standing wave oscillates, and laser light in the 1100 nm band is output upward from the opening 125 of the p-side annular electrode 121.

  Next, the manufacturing method of the surface emitting laser 100 of the said embodiment is demonstrated.

First, the lower DBR mirror 102, the buffer layer 103, the n ⁺ -type contact layer 104, the n-type spacer layer 105, the active layer 106, the p-type spacer layer 108, and the lower pseudo composition gradient layer 109 are formed on the substrate 101 by the MBE method. Then, an Al _0.98 Ga _0.02 As layer 110 ′, an upper pseudo composition gradient layer 111, a p-type spacer layer 112, and a p ⁺ -type contact layer 115 are sequentially stacked.

Next, a disc-shaped dielectric layer 141 made of SiN _x is selectively formed in a partial region of the p ⁺ -type contact layer 115 by using a CVD method and a photolithography method.

Next, the p-side annular electrode 121 is selectively formed on the p ⁺ -type contact layer 115 by using a lift-off method.

  Next, using the p-side annular electrode 121 as a metal mask, the semiconductor stack up to a depth reaching the n-type contact layer 104 is etched using an acid etching solution or the like to form a cylindrical mesa post 130. Next, another mask is formed, and the n-type contact layer 104 is etched to a depth reaching the buffer layer 103. As a result, the mesa post 130 having the shape shown in FIG. 1 is obtained. Since the mesa post 130 is formed in a self-aligned manner with the p-side annular electrode 121, the mesa post 130 can be formed with high dimensional accuracy.

Next, when heat treatment is performed at about 450 ° C. for about 1 hour in a steam atmosphere, the Al _0.98 Ga _0.02 As layer 110 ′ is selectively oxidized from the side surface 132 of the mesa post 130, and Al ₂ O ₃ is removed. The current confinement portion 110b is formed by changing to an oxide film having a main component. The chemical reaction proceeds almost uniformly from the outer peripheral side of the Al _0.98 Ga _0.02 As layer 110 ′, and the current injection portion 110a made of Al _0.98 Ga _0.02 As is left in the center. The processing time in the selective oxidation is adjusted, and the diameter of the current injection unit 110a is set to 6 μm, for example. By this selective oxidation, the center of the mesa post 130, the center of the current injection portion 110b, and the center of the opening 125 of the p-side annular electrode 121 can be matched with high accuracy.

  Thereafter, as shown in FIG. 1, a semi-circular n-side electrode 131 is formed on the surface of the n-type contact layer 104 on the outer peripheral side of the mesa post 130. Next, after forming a passivation film 145 on the entire surface by CVD, openings (not shown) are formed in the passivation film 145 on the n-side electrode 131 and the p-side annular electrode 121. Furthermore, an n-side extraction electrode (not shown) that contacts the n-side electrode 131 and a p-side extraction electrode (not shown) that contacts the p-side annular electrode 121 via these openings (not shown). Form.

  Next, after forming the upper DBR 150 made of a dielectric using the CVD method, the back surface of the substrate 101 is polished, and the thickness of the substrate 101 is adjusted to, for example, 150 μm. Thereafter, element isolation is performed to complete the surface emitting laser 100 shown in FIG.

  Next, the lower pseudo composition gradient layer 109, the current confinement layer 110, and the upper pseudo composition gradient layer 111 will be described in more detail with reference to FIGS.

As shown in FIG. 2, the current confinement layer 110 includes a central current injection portion 110a and a current confinement portion 110b around the current injection portion 110a. The current injection portion 110 a is in the central region 161, and the current constriction portion 110 b is in the surrounding region 162. The current injection portion 110a is made of Al _0.98 Ga _0.02 As, and the current constriction portion 110b is made of aluminum oxide formed mainly by oxidizing Al _0.98 Ga _0.02 As.

  The upper pseudo-gradient composition layer 111 is located in the central region 161 and is located in a position facing the current injection portion 110a and in the surrounding region 162 and is located in a location facing the current confinement portion 110b. An oxide region 111b and a semiconductor region 111c are provided.

  The semiconductor region 111a is in contact with the current injection part 110a and the p-type spacer layer 112. The oxide region 111b is in contact with the current confinement portion 110b, and the semiconductor region 111c is in contact with the oxide region 111b and the p-type spacer layer 112. The semiconductor region 111c has the same structure as the structure that the semiconductor region 111a has from the interface with the p-type spacer layer 112 toward the current confinement layer 110 as it goes from the interface with the p-type spacer layer 112 to the current confinement layer 110. Yes. The p-type spacer layer 112 is made of p-type GaAs.

  The lower pseudo composition gradient layer 109 is in the central region 161 and is located in the semiconductor region 109a facing the current injection portion 110a and in the surrounding region 162 and facing the current confinement portion 110b. An oxide region 109b and a semiconductor region 109c are provided.

  The semiconductor region 109 a is in contact with the current injection part 110 a and the p-type spacer layer 108. The oxide region 109b is in contact with the current confinement portion 110b, and the semiconductor region 109c is in contact with the oxide region 109b and the p-type spacer layer. The semiconductor region 109c has the same structure as the semiconductor region 109a has from the interface with the p-type spacer layer 108 toward the current confinement layer 110 as it goes from the interface with the p-type spacer layer 108 to the current confinement layer 110. Yes. The uppermost layer of the p-type spacer layer 108 is made of GaAs.

  Next, the upper pseudo composition gradient layer 111 will be described in more detail. The lower pseudo composition gradient layer 109 is configured such that the upper pseudo composition gradient layer 109 is interfaced with the current confinement layer 110 as the lower pseudo composition gradient layer 109 moves from the interface with the current confinement layer 110 toward the p-type spacer layer 108. Since the structure has the same structure as the structure from the first to the p-type spacer layer 112, the description of the lower pseudo composition gradient layer 109 is omitted.

  As shown in FIG. 3, the semiconductor region 111 a of the upper pseudo gradient composition layer 111 has five pseudo AlGaAs layers 171 to 175. The film thickness of the upper pseudo gradient composition layer 111 is 10 nm, and the film thicknesses of the pseudo AlGaAs layers 171 to 175 are 2 nm. The thickness of the AlGaAs layer 110 (current injection portion 110a) is 20 nm.

The pseudo AlGaAs layer 171 includes a GaAs layer 171a and an AlGaAs layer 171b. The AlGaAs layer 171b is made of Al _0.98 Ga _0.02 As and has the same composition as that of the current injection portion 110a. The GaAs layer 171a has a film thickness of about 0.21 nm, the AlGaAs layer 171b has a film thickness of about 1.79 nm, and the pseudo Al composition of the GaAs layer 171a and the AlGaAs layer 171b is 0.9. An AlGaAs layer 171 is formed.

The pseudo AlGaAs layer 172 includes a GaAs layer 172a and an AlGaAs layer 172b. The AlGaAs layer 172b is made of Al _0.98 Ga _0.02 As. The thickness of the GaAs layer 172a is about 0.42 nm, the thickness of the AlGaAs layer 172b is about 1.58 nm, and the pseudo Al composition is 0.8 between the GaAs layer 172a and the AlGaAs layer 172b. An AlGaAs layer 172 is formed.

The pseudo AlGaAs layer 173 includes a GaAs layer 173a and an AlGaAs layer 173b. The AlGaAs layer 173b is made of Al _0.98 Ga _0.02 As. The GaAs layer 173a has a thickness of about 0.85 nm, the AlGaAs layer 173b has a thickness of about 1.15 nm, and the pseudo Al composition of the GaAs layer 173a and the AlGaAs layer 173b is 0.6. An AlGaAs layer 173 is formed.

The pseudo AlGaAs layer 174 includes a GaAs layer 174a and an AlGaAs layer 174b. The AlGaAs layer 174b is made of Al _0.98 Ga _0.02 As. The GaAs layer 174a has a thickness of about 1.28 nm, the AlGaAs layer 174b has a thickness of about 0.72 nm, and the pseudo Al composition of the GaAs layer 174a and the AlGaAs layer 174b is 0.4. An AlGaAs layer 174 is formed.

The pseudo AlGaAs layer 175 includes a GaAs layer 175a and an AlGaAs layer 175b. The AlGaAs layer 175b is made of Al _0.98 Ga _0.02 As. The GaAs layer 175a has a thickness of about 1.7 nm, the AlGaAs layer 175b has a thickness of about 0.3 nm, and the pseudo Al composition of the GaAs layer 175a and the AlGaAs layer 175b is 0.2. An AlGaAs layer 175 is formed. The unevenness of the oxide layer finally obtained is almost determined by the width of each step (here, for example, the widths of 171, 172, 173, 174, and 175) (the same applies to the subsequent embodiments). To be set).

  As described above, the semiconductor region 111a of the upper pseudo gradient composition layer 111 includes the film thickness a of the AlGaAs layers 171b, 172b, 173b, 174b, and 175b, and the film thickness b of the GaAs layers 171a, 172a, 173a, 174a, and 175a. This is a pseudo AlGaAs composition gradient layer in which the Al composition changes in a pseudo manner by decreasing the Al ratio (a / b) from the AlGaAs layer 110 (current injection portion 110a) toward the p-type spacer layer 112. As a result, current can easily flow and current injection efficiency can be improved.

  In addition, the GaAs layers 171a, 172a, 173a, 174a, and 175a having the same composition and the AlGaAs layers 171b, 172b, 173b, 174b, and 175b having the same composition are alternately stacked while changing the film thickness. When growing, since the temperature of the raw material source (cell) may be kept the same, the controllability of the flux and the reproducibility of the composition profile are excellent.

  The oxide region 111b is an oxide obtained by oxidizing the GaAs layer 171a, the AlGaAs layer 171b, the GaAs layer 172a, the AlGaAs layer 172b, the GaAs layer 173a, and the AlGaAs layer 173b, and is mainly composed of aluminum oxide. Under the conditions of this project, the boundary between the oxide region 111b and the semiconductor region 111c was included in steps 173a and 173b, and the unevenness of the boundary was 2 nm or less. However, the boundary portion may exist in the layer 172 having a pseudo Al composition of 0.8 or other layers depending on the oxidation conditions.

  The semiconductor region 111c has the same structure as the structure that the semiconductor region 111a goes from the interface with the p-type spacer layer 112 toward the current confinement layer 110 as it goes from the interface with the p-type spacer layer 112 toward the current confinement layer 110. ing. That is, an AlGaAs layer 175b, a GaAs layer 175a, an AlGaAs layer 174b, and a GaAs layer 174a are provided from the interface with the p-type spacer layer 112 toward the current confinement layer 110.

  Next, a method for forming the current injection portion 110b by oxidation and the oxide regions 111b and 109b formed at that time will be described.

As shown in FIGS. 4 and 5, the GaAs layer 171a, the AlGaAs layer 171b, the GaAs layer 172a, the AlGaAs layer 172b, the GaAs layer 173a, the AlGaAs layer 173b, and the GaAs layer are formed on the Al _0.98 Ga _0.02 As layer 110 ′. An upper pseudo composition gradient layer 111 having 174a, an AlGaAs layer 174b, a GaAs layer 175a, and an AlGaAs layer 175b is formed. An upper pseudo composition gradient layer 109 having a similar structure is also formed below the Al _0.98 Ga _0.02 As layer 110 ′. Since the lower side is in the downward direction with respect to the hole, the step difference is not so important. Therefore, the stacking process may be simplified by designing the number of steps on the lower side to be smaller than that on the upper side. It is convenient from the viewpoint of the stacking process that the number of steps is 3 to 15 for the upper step and 2 to 10 for the lower step. From the viewpoint of electrical resistance, it is convenient that the apparent composition difference between adjacent steps (including a layer adjacent to the composition gradient layer) is 0.5 or less.

Next, when heat treatment is performed in a water vapor atmosphere at about 450 ° C. for about 1 hour, the Al _0.98 Ga _0.02 As layer 110 ′ is exposed in the oxidation direction 165 from the side surface 132 of the mesa post 130 as shown in FIG. Along with this, it is changed into an oxide film containing aluminum oxide as a main component, and a current confinement portion 110b is formed. The chemical reaction proceeds almost uniformly from the outer peripheral side of the Al _0.98 Ga _0.02 As layer 110 ′, and the current injection portion 110a made of Al _0.98 Ga _0.02 As is left in the center. At this time, the oxidation also proceeds in the oxidation direction 166, and the GaAs layer 171a, the AlGaAs layer 171b, the GaAs layer 172a, the AlGaAs layer 172b, the GaAs layer 173a, and the AlGaAs layer 173b are oxidized to form the oxide region 111b. An oxide region 109b is formed.

In the preferred first embodiment of the present invention, the current injection part 110a is made of Al _0.98 Ga _0.02 As, but can also be made of AlAs. In this case, the current confinement portion 110b is mainly made of an aluminum oxide in which AlAs is oxidized.

FIG. 12 is a diagram showing the relationship between the Al composition x (%) of Al _x Ga _1-x As and the oxidation rate when the oxidation rate of AlAs is 1, from which the Al composition x (%) It can be seen that an inflection point exists at 93%. Therefore, the current injection part 110a is preferably composed of AlAs or Al _x Ga _1-x As (0.93 ≦ x <1), and the current constriction part 110b is made of AlAs or Al _x Ga _1-x As (0.93). ≦ x <1) is preferably composed of an oxide mainly composed of oxidized aluminum oxide.

In the preferred embodiment of the present invention, the composition of the AlGaAs layers 171b, 172b, 173b, 174b, and 175b is Al _0.98 Ga _0.02 As, which is the same as that of the current injection portion 110a of the current confinement layer 110. AlGaAs having a lower Al content than the portion 110a may be used.

The composition of the AlGaAs layers 171b, 172b, 173b, 174b, and 175b is preferably Al _x Ga _1-x As (0.75 ≦ x ≦ 0.99), and more preferably Al _x Ga _1-x As ( 0.85 ≦ x ≦ 0.98). This is because the oxidation rate in the horizontal direction of the current confinement layer and the oxidation rate in the vertical direction of the pseudo composition gradient layer are approximately the same.

  In the first embodiment of the present invention, the pseudo AlGaAs layers 171, 172, 173, 174, 175 are replaced with the AlGaAs layers 171b, 172b, 173b, 174b, 175b and the GaAs layers 171a, 172a, 173a, 174a, The pseudo AlGaAs layers 171, 172, 173, 174, and 175 are composed of the first AlGaAs and the second AlGaAs having a lower Al content than the first AlGaAs. You may comprise with 2nd AlGaAs by the side of a constriction layer.

  Variation t1 in the boundary between the oxide region 111b and the non-oxidized semiconductor region 111c, and variation t1 in the boundary between the oxide region 109b and the non-oxidized semiconductor region 109c, that is, the oxide region 111b is not oxidized. When the unevenness t1 at the boundary between the semiconductor region 111c and the unevenness t1 at the boundary between the oxide region 109b and the unoxidized semiconductor region 109c is 4 nm or less, it is advantageous because local distortion that causes peeling is less likely to occur. More preferably, when the thickness is 2 nm or less, peeling of the interface hardly occurs.

  Preferably, the thickness of the current injection portion 110a is not more than λ / 4n, more preferably not more than λ / 8n, where the oscillation wavelength λ of the semiconductor laser device 100 is n, where n is the refractive index of the semiconductor. By setting this film thickness, optical loss due to the current confinement layer can be suppressed.

  Next, the structure of the semiconductor laser device of the second embodiment will be described. In the first embodiment, the semiconductor region 111a of the upper pseudo gradient composition layer 111 is formed in the AlGaAs layers 171b, 172b, 173b, 174b having the same composition as the GaAs layers 171a, 172a, 173a, 174a, 175a having the same composition. 175b are alternately stacked while changing the film thickness. However, as shown in FIGS. 6 and 7, in the second embodiment, the semiconductor region 111a of the upper pseudo composition gradient layer 111 is formed by the composition. The GaAs layers 181a, 182a, 183a, 184a, 185a having the same composition and the AlAs layers 181b, 182b, 183b, 184b, 185b having the same composition are alternately stacked while changing the film thickness. The average Al composition of the GaAs layer 181a having a thickness of 0.25 nm and the AlAs layer 181b having a thickness of 2.25 nm is 0.9. The pseudo AlGaAs layer 181 is configured, and the pseudo AlGaAs layer 182 having an average Al composition of 0.8 is configured by the 0.5 nm thick GaAs layer 182a and the 2 nm thick AlAs layer 182b. The 1 nm GaAs layer 183a and the 1.5 nm thick AlAs layer 183b constitute a pseudo AlGaAs layer 183 having an average Al composition of 0.6, and the 1.5 nm thick GaAs layer 184a and the 1 nm thick film thickness. The pseudo AlGaAs layer 184 having an average Al composition of 0.4 is formed with the AlAs layer 184b, and the average Al composition is composed of the GaAs layer 185a with a thickness of 2 nm and the AlAs layer 185b with a thickness of 0.5 nm. And the semiconductor region 109a of the lower pseudo composition gradient layer 109 is also a semiconductor of the upper pseudo composition gradient layer 111. That were configured similarly to the band 111a is above, but differs from the first embodiment, it is similar to including other points such as the manufacturing method. In this case as well, several cases in which the oxidation conditions were changed were tried, but the average unevenness was the total width of adjacent AlAs steps (here, about 3.5 nm).

Next, the structure of the semiconductor laser device according to the third embodiment will be described. In the first embodiment, the semiconductor region 111a of the upper pseudo-gradient composition layer 111 is formed on the AlGaAs layers 171b, 172b, 173b, 174b, 175b having the same composition as the GaAs layers 171a, 172a, 173a, 174a, 175a having the same composition. As shown in FIG. 8, in the third embodiment, the upper pseudo composition gradient layer 111 is made of Al _0.9 Ga having a thickness of 2 nm. _0.1 As layer 191, 2 nm thick Al _0.8 Ga _0.2 As layer 192, 2 nm thick Al _0.6 Ga _0.4 As layer 193, 2 nm thick Al _0.4 a Ga _0.6 as layer 194, constitute a _Al 0.2 _{Ga 0.8} as layer 195 having a thickness of 2nm to intervening GaAs layer 196 having a thickness of 0.5nm between the respective layers, the lower Similar composition gradient layer 109, the point that is configured similarly to the upper pseudo composition gradient layer 111, differs from the first embodiment, the other points are the same. The thickness of the inserted GaAs layer is advantageously 0.1, particularly 0.2 nm or more, from the effect of a barrier against oxidation, and 1.0, particularly 0.5 nm or less, from the effect on the composition. In this case, the unevenness was about the width of the step.

  Next, a fourth embodiment is shown in FIG. The semiconductor region 111 a of the upper pseudo gradient composition layer 111 has five pseudo AlGaAs layers 171 to 175. The film thickness of the upper pseudo gradient composition layer 111 is 10 nm, and the film thicknesses of the pseudo AlGaAs layers 171 to 175 are 2 nm. Each of the pseudo AlGaAs layers is made of Al0.98Ga0.02As and has the same composition as that of the current injection portion 110a. The thickness of the GaAs layer 171a of the pseudo AlGaAs layer 171 is about 0.21 nm, the thickness of the AlGaAs layer 171b is about 1.79 nm, and the average Al composition of the GaAs layer 171a and the AlGaAs layer 171b is 0. .9, a pseudo AlGaAs layer 171 is formed.

  The pseudo AlGaAs layer 172 includes a GaAs layer 172a and an AlGaAs layer 172b. The thickness of the GaAs layer 172a is about 0.42 nm, the thickness of the AlGaAs layer 172b is about 1.58 nm, and the pseudo Al composition is 0.8 between the GaAs layer 172a and the AlGaAs layer 172b. An AlGaAs layer 172 is formed.

  The pseudo AlGaAs layer 173 includes a GaAs layer 173a and an AlGaAs layer 173b. The thickness of the GaAs layer 173a is about 0.63 nm, the thickness of the AlGaAs layer 173b is about 1.37 nm, and the pseudo Al composition of 0.7 is average between the GaAs layer 173a and the AlGaAs layer 173b. An AlGaAs layer 173 is formed.

  The pseudo AlGaAs layer 174 includes a GaAs layer 174a and an AlGaAs layer 174b. The thickness of the GaAs layer 174a is approximately 0.84 nm, the thickness of the AlGaAs layer 174b is approximately 1.16 nm, and the pseudo Al composition of the GaAs layer 174a and the AlGaAs layer 174b is 0.6. An AlGaAs layer 174 is formed.

  The pseudo AlGaAs layer 175 includes a GaAs layer 175a and an AlGaAs layer 175b. The thickness of the GaAs layer 175a is about 1.5 nm, the thickness of the AlGaAs layer 175b is about 0.5 nm, and the pseudo Al composition of the average Al composition of the GaAs layer 175a and the AlGaAs layer 175b is 0.3. An AlGaAs layer 175 is formed. The unevenness was about the width of the step.

  In this embodiment, the electrical resistance is reduced by making the composition change on the active layer side gentle and steep on the side opposite to the active layer.

  Comparing the first to fourth embodiments, in the second embodiment, the thin GaAs layers 181a, 182a and the like function as an oxidation barrier as in the other embodiments. However, when the thin GaAs layer 181a is oxidized, since the AlAs layer 181b has a high oxidation rate, it is immediately oxidized and reaches the next GaAs layer 182a. Next, when the next thin GaAs layer 182a is oxidized, since the AlAs layer 182b has a high oxidation rate, it is immediately oxidized and reaches the next GaAs layer 183a. As a result, compared to other embodiments, the oxidation rate in the film thickness direction is affected by the variation in the film thickness of the thin GaAs layers 181a, 182a, etc., and the oxide region 111b is oxidized as shown in FIG. The variation t2 of the boundary with the unexposed semiconductor region 111c becomes large, the boundary meanders greatly, and local distortion is likely to occur. Further, AlAs is brittle in material, and when oxidized, the volume change is large and stress strain occurs. This introduces dislocations in the crystal during the long-term energization of the element and propagates it, so that the reliability of the element is significantly reduced. As described above, the fragile AlAs is likely to be distorted, the current confinement portion 110b and the like are peeled off, and the mesa post 130 is easily broken. When the first to fourth embodiments were compared, the variation in the film thickness was larger in the order of the second embodiment> the fourth embodiment> the third embodiment> the first embodiment.

  On the other hand, AlGaAs used in the first, third, and fourth embodiments has higher crystal strength than AlAs, and the strength is dramatically increased even if a little Ga enters AlAs. AlGaAs is a material whose oxidation rate is reduced by about 30% only by changing the Al composition by 1%. Therefore, as in the first, third, and fourth embodiments, the upper pseudo composition gradient layer 111 and the lower pseudo composition gradient layer 109 are configured by a combination of AlGaAs and GaAs, whereby the AlGaAs layer 171b, 172b or the like has a low oxidation rate, so it is not immediately oxidized, and the influence of the oxidation rate in the film thickness direction due to the variation in the film thickness of the thin GaAs layers 181a and 182a is alleviated. As shown in FIG. The variation t1 of the boundary between the region 111b and the non-oxidized semiconductor region 111c is small, the meandering of the boundary is also small, and local distortion is hardly generated. Further, since AlGaAs has a higher crystal strength than AlAs, it has a structure with excellent mechanical strength, and an element with excellent reliability can be obtained.

Next, the structure of the comparative example will be described. In the first embodiment, the semiconductor region 111a of the upper pseudo-gradient composition layer 111 is formed on the AlGaAs layers 171b, 172b, 173b, 174b, 175b having the same composition as the GaAs layers 171a, 172a, 173a, 174a, 175a having the same composition. As shown in FIG. 10, in the comparative example, the upper pseudo composition gradient layer 111 is made of Al _0.9 Ga _0.1 As having a thickness of 2 nm. A layer 191, a 2 nm thick Al _0.8 Ga _0.2 As layer 192, a 2 nm thick Al _0.6 Ga _0.4 As layer 193, and a 2 nm thick Al _0.4 Ga _{0.6 layer.} the as layer 194, composed of the _Al 0.2 _{Ga 0.8} as layer 195 having a thickness of 2 nm, the lower pseudo composition gradient layer 109, the point that is configured similarly to the upper pseudo composition gradient layer 111 , Differs from the first embodiment, the other points are the same.

  FIG. 11 is a diagram showing the relationship between the thermal shock test temperature and the rate of occurrence of mesa post breakdown as a result of performing a thermal shock test on the laser device of the first embodiment of the present invention and the laser device of the comparative example. It is. In the laser element of the comparative example, a sample in which mesa post breakdown occurred near 370 ° C. began to appear, and mesa post breakdown occurred in almost all samples near 400 ° C. On the other hand, in the laser device according to the first preferred embodiment of the present invention, there was no sample causing mesa post breakdown even at 420 ° C. Even if the mesa post breakdown does not occur even at 420 ° C., it is considered that the mesa post breakdown does not occur even during the CVD process for forming the passivation film 145 and the upper DBR mirror 150 and during the long-term energization of the element. It can be seen that the laser element of the embodiment is very reliable. Further, the laser elements of the second to fourth embodiments were less mesa-post-destructed than the laser elements of the comparative example, although not as much as the laser elements of the first embodiment.

  Furthermore, the inventors made samples in which the oxide constriction layer including the composition gradient layer based on the first embodiment on both sides was provided at various distances from the active layer, and the deviation from the design value of the oscillation wavelength was reduced. The device characteristics were examined by conducting an energization test for 400 hours. It was confirmed that in the sample with the film thickness unevenness of 4 nm or less, the generation of dislocations in the active layer was effectively suppressed in the sample in which the distance from the active layer to the center of the oxidized constriction layer was set to 40 to 600 nm. . Further, it was confirmed that the wavelength shift and dislocation were substantially eliminated even in the sample set to 40 to 200 nm in the sample having a thickness of 2 nm or less, and effectively suppressed at 40 to 100 nm.

  Here, the first p-type spacer layer may be configured as a layer having a compressive strain containing In. For example, as the first p-type spacer layer, p-GaInP may be substituted, or a 5 to 10 nm layer may be inserted into the first p-type spacer layer. When forming the oxidized constricting layer, a large strain occurs at the boundary between the oxidized region and the non-oxidized layer of the oxidized constricting layer, and this strain and the strain caused by the irregularities formed at the interface between the oxidized constricting layer and the adjacent layer affect each other. Although dislocations were generated, the defect rate could be further reduced by inserting a layer having a compressive strain containing In.

  In the embodiment of the present application, the oxide constriction layer is viewed from the active layer in consideration of the position of the node of the standing wave of light in the resonator so as to minimize the diffraction of oscillation light. However, it may be formed closer to the active layer in order to lower the threshold value. Furthermore, the current confinement layer can be formed above and below the active layer to enhance the current confinement effect.

  In the above-described embodiment, the case where the oxide constriction layer is provided in the resonator has been described. However, the semiconductor DBR mirror composed of an AlGaAs / GaAs pair is applied to a surface emitting laser including the oxide confinement layer, and the mirror is peeled off. It can also be suppressed.

  In the above-described embodiments, the Al oxide constriction layer formed on the GaAs substrate and the composition gradient layer provided on the periphery thereof have been described. However, the activity of the InGaAs strained quantum well structure on the InGaAs substrate is described. Other III-V group compounds may be used for the substrate and other layers, such as providing an oxidized constricting layer made of InAlAs on the layer and the active layer, and further providing a composition gradient layer on both sides of the oxidized constricting layer.

  In the above-described embodiment, the surface emitting laser element in which the active layer is formed of an InGaAs-based material and the oscillation wavelength is in the 1.1 μm band has been described as an example. However, the oscillation wavelength band of the surface emitting laser element and the active layer are described. The material which comprises etc. can be selected suitably. For example, if the oscillation wavelength is 850 nm, an AlGaAs-based material and a surface emitting laser element whose oscillation wavelength is in the 1.3 to 1.6 μm band can select an AlGaInAs-based material, a GaInNAs-based material, and a GaInNAsSb-based material. It is.

  The semiconductor laser device according to the preferred embodiment of the present invention is a surface emitting laser device. However, the structure and manufacturing method of the semiconductor laser device according to the preferred embodiment of the present invention may be applied to an edge emitting semiconductor laser device. In this case, the current confinement layer 110 includes a central current injection portion 110a and current confinement portions 110b on both sides thereof.

  In this application, the unevenness | corrugation was measured with SEM (scanning electron microscope). Further, in the case of the oxidized constriction layer formed on the mesa post, the unevenness increases on the outer peripheral side of the mesa post, that is, the base portion of the oxidized portion, and the center side of the mesa post, that is, the tip end portion in the plane of the oxidized portion. Therefore, in this application, in order to avoid large unevenness at the base portion and the distal end portion, measurement was performed on a relatively uniform portion of the unevenness near the central portion in the oxidation direction of the oxidized portion.

  Next, an example of a surface emitting laser array using a plurality of surface emitting semiconductor laser elements 100 according to a preferred embodiment of the present invention will be described with reference to FIGS. As an example, as shown in FIG. 13, a surface emitting laser array chip 700 mounted on a known flat package 710 called CLCC (Ceramic Leaded Chip Carrier) is used. In the figure, the connection between the metal caster (electrode) 714 and the surface emitting laser array chip 700 is omitted for the sake of simplicity. As shown in FIG. 14, the surface emitting laser array chip 700 includes an element portion 702 including a plurality of surface emitting semiconductor laser elements 100 provided in the central portion, and a plurality of light emitting portions of the element portion 702 provided around the element portion 702. And a plurality of electrode pads 706 connected (not shown). Furthermore, each electrode pad 706 is connected to a metal caster 714 of the flat package 712 (not shown). Each light emitting unit is controlled to emit light by an external control circuit (not shown) connected to the flat package 712, and emits laser light having a predetermined wavelength.

  Next, an example in which the surface emitting semiconductor laser device 100 according to the preferred embodiment of the present invention is applied to an optical apparatus will be described with reference to the drawings. FIG. 15 is a schematic longitudinal sectional view showing a configuration when the surface emitting semiconductor laser device 100 according to the preferred embodiment of the present invention is applied to a package of a light emitting device. The surface emitting laser package 300 includes a surface emitting semiconductor laser element 100, a surface emitting laser module including a substrate 304 and an electrode 306, a lens 316, a housing 310, an optical fiber mount 312, and an optical fiber 314. The electrode 306 is electrically connected to an external control circuit (not shown), and the light emission of the surface emitting laser package is controlled. Laser light emitted from the surface emitting semiconductor laser element 100 is condensed by a lens 316 and coupled to an optical fiber 314.

  FIG. 16 is a schematic longitudinal sectional view showing a configuration when the surface-emitting type semiconductor laser device 100 according to the preferred embodiment of the present invention is applied to a pickup of a writing / reading device for an optical storage medium. The pickup 350 includes a surface emitting laser module including a surface emitting semiconductor laser element 100, a substrate 354, an electrode 356, a driving IC 358, and a resin 360 that seals these elements, a lens 376, a half mirror 370, a diffraction grating 374, An optical sensor 380 and an optical storage medium 372 are included. The exit surface of the resin 360 is processed into a convex shape to constitute a lens 362. The electrode 3546 is electrically connected to an external control circuit (not shown), and the light emission of the laser pickup is controlled. Laser light emitted from the surface emitting semiconductor laser element 100 is converted into parallel light by the lens 362, reflected by the half mirror 370, collected by the lens 376, and collected at a predetermined location on the optical storage medium 372. . Further, the light reflected by the optical medium is incident on the optical sensor 380. Here, the surface-emitting semiconductor laser device 100 or the surface-emitting laser device array having a plurality of surface-emitting semiconductor laser devices 100 according to the preferred embodiment of the present invention is applied to a light-emitting device package for communication or an optical disk pickup. An example is shown, but the present invention is not limited to this, and it is used as an optical instrument such as a surveying instrument, laser pointer, optical mouse, printer, photoresist scanning exposure light source, laser pumping light source, processing fiber laser light source, etc. You can also.

  FIG. 17 is a schematic configuration diagram of an optical transceiver module to which the surface emitting semiconductor laser device 100 according to the preferred embodiment of the present invention is applied. As shown in FIG. 17, the optical transceiver module 400 includes a holding member 402, an optical waveguide (optical fiber) 412, a spacer 410 for positioning the optical waveguide (optical fiber) 412 on the holding member 402, and an optical waveguide (optical fiber). ) A surface emitting semiconductor laser element 100 that transmits an optical signal via 412 or a surface emitting laser element array having a plurality of surface emitting semiconductor laser elements 100, a light receiving element 404 that receives an optical signal, and a surface emitting semiconductor laser element 100. Alternatively, the driving circuit 406 controls the light emission state of the surface emitting laser element array, and the amplifier circuit 408 amplifies the signal received by the light receiving element 404. The surface emitting semiconductor laser element 100 or the surface emitting laser element array is controlled to emit light via a drive circuit 406 by a control signal from an external control unit (not shown), and a signal received by the light receiving element 404 is amplified. Is transmitted to the control unit. In order to avoid complication, the wire bonding of the drive circuit 406 and the surface emitting semiconductor laser element 100 or the surface emitting laser element array / amplifier circuit 408 and the light receiving element 404 is omitted.

  18 to 20 are schematic configuration diagrams of an optical coupling portion between the surface-emitting semiconductor laser device 100 or the surface-emitting laser device array and the optical waveguide 412 in FIG. 17, and the substrate 500, the surface-emitting semiconductor laser device 100 or The surface emitting laser element array and the optical waveguide 412 are common in FIGS. In FIG. 18, the end surface of the waveguide 412 is processed so as to be inclined at approximately 45 degrees with respect to the optical axis. Further, this inclined surface is used as a reflecting surface 504 and is subjected to mirror surface processing such as coating of a reflecting film. Light emitted from the surface-emitting type semiconductor laser device 100 or the surface-emitting laser device array enters the waveguide from the lower surface of the waveguide 412, is reflected by the inclined surface 504, and propagates through the optical waveguide 412. In FIG. 19, on the surface-emitting semiconductor laser device 100 or the surface-emitting laser device array, a mirror assembly 506 having a reflection surface 504 provided therein is provided on the side of the end surface of the optical waveguide 412 to thereby provide a surface-emitting semiconductor laser device. The light emitted from 100 or the surface emitting laser element array is incident from the lower surface of the mirror assembly 506, reflected by the reflecting surface 504, and the light emitted from the mirror assembly 506 is coupled to the optical waveguide 412 to pass through the optical waveguide 412. Propagate. A microlens (array) may be provided on the entrance surface and / or the exit surface of the mirror assembly 506. In FIG. 20, the optical fiber 412 is disposed in the connector housing 512, and the end portion of the curved portion 514 of the optical fiber core wire is disposed so as to face the surface emitting semiconductor laser element 100 or the surface emitting laser element array. Light emitted from the surface emitting semiconductor laser element 100 or the surface emitting laser element array is coupled to the optical fiber 412.

  Next, an example in which a surface emitting laser element 100 or a surface emitting laser element array having a plurality of surface emitting semiconductor laser elements 100 according to a preferred embodiment of the present invention is applied to a communication system will be described. FIG. 21 shows a configuration example of a wavelength multiplexing transmission system using the surface emitting semiconductor laser element 100 or the surface emitting laser element array. The wavelength multiplexing transmission system of FIG. 21 includes a computer, a board or chip 602, a communication control circuit (CPU, MPU, optical-electrical conversion circuit, electrical-optical conversion circuit, wavelength control circuit) 604, and a plurality of surface emitting semiconductor laser elements 100. It includes a surface emitting laser element array 606, a light receiving element integrated unit 608, a multiplexer 610, a duplexer 612, an electrical wiring 616, optical fibers 617 and 618, a communication target network, a PC, a board, a chip, and the like 614. In the wavelength multiplexing transmission system of FIG. 21, a surface emitting laser array 606 is configured by arranging a plurality of surface emitting laser elements having different oscillation wavelengths, and each oscillation light from each surface emitting laser element of the surface emitting laser array 606 is combined. It is configured to be coupled to one optical fiber through a waver. In such a configuration, a large amount of signal can be transmitted with high throughput with a single fiber. As described above, the surface emitting laser array according to the preferred embodiment of the present invention is stable in mode and stable in each oscillation wavelength. It becomes possible. In this embodiment, the output optical fiber or the input optical fiber from each surface emitting laser array 606 or the light receiving element integrated unit 608 is coupled to one optical fiber using the multiplexer 610 or the demultiplexer 612. However, depending on the application, an output optical fiber or an input optical fiber can be directly connected to a communication target network, PC, board, chip, or the like 614 to form a parallel transmission system. In this case, since the surface emitting laser array according to the preferred embodiment of the present invention has a stable mode and each wavelength is stable, a highly reliable parallel transmission system having a plurality of light sources can be constructed. It becomes easy.

  While various typical embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Accordingly, the scope of the invention is limited only by the following claims.

DESCRIPTION OF SYMBOLS 100 Surface emitting semiconductor laser element 101 Substrate 102 Lower DBR mirror 103 Buffer layer 104 n ⁺ type contact layer 105 n type spacer layer 106 Active layer 108 First p type spacer layer 109 Lower pseudo composition gradient layer 109a Semiconductor region 109b Oxidation Physical region 109c semiconductor region 110 current confinement layer 110a current injection portion 110b current confinement portion 110 ′ Al _0.98 Ga _0.02 As layer 111 upper pseudo composition gradient layer 111a semiconductor region 111b oxide region 111c semiconductor region 112 second p-type spacer layer 113 p ⁺ -type current path layer 115 p ⁺ -type contact layer 120 cavity 121 p-side annular electrode 125 opening 130 mesa post 131 n-side electrode 132 side 141 dielectric layer 143 SiO ₂ film 144 SiN _x film 145 package Bavation film 150 Upper DBR mirror 161, 162 region 165, 166 Oxidation direction 171-175 Pseudo AlGaAs layer 171a-175a GaAs layer 171b-175b AlGaAs layer 181-185 Pseudo AlGaAs layer 181a-185a GaAs layer 181b-185b AlAs layer 19 ~ 195 AlGaAs layer

Claims (15)

Formed on a III-V compound substrate;
A resonator region comprising an active layer and an Al-containing oxide constriction layer;
A surface emitting laser comprising a pair of DBR mirrors facing each other so as to sandwich the resonator region,
On both sides of the Al-containing oxide constriction layer, the Al-containing oxide constriction layer includes a plurality of steps including an Al-containing III-V group compound and an Al-free III-V group compound. A surface-emitting laser, wherein a pseudo composition gradient layer that continuously decreases as the distance from the oxidized constricting layer is formed, and a part thereof is oxidized from an interface adjacent to the Al-containing oxidized constricting layer. The surface emitting laser according to claim 1, wherein the Al-containing oxide constriction layer is Al _x Ga _1-x As (0.93 ≦ x <1). The Al-containing III-V compound is Al _x Ga _1-x As (0.75 ≦ x ≦ 0.99), the Al-free III-V compound is GaAs, and the Al-containing III-V Forming a pseudo composition gradient layer by combining the steps of forming the pseudo composition by changing the film thickness of the group III compound and the Al-free III-V group compound so that the composition continuously changes. The surface emitting laser according to claim 1 or 2, characterized in that   The Al-containing group III-V compound is AlAs, the Al-free group III-V compound is GaAs, and changes the film thickness of the Al-containing group III-V compound and the Al-free group III-V compound. 3. The surface emitting laser according to claim 1, wherein the pseudo composition gradient layer is formed by combining the steps constituting the pseudo composition so that the composition continuously changes. The Al-containing III-V group compound is Al _x Ga _1-x As (0 ≦ x ≦ 0.99), the Al-free III-V group compound is GaAs, the film thickness is constant, and the Al composition A pseudo composition by combining the steps of the Al-containing III-V group compound having different thicknesses and the Al-non-containing III-V group compound having a film thickness of 0.1 to 0.5 nm so that the composition continuously changes. The surface emitting laser according to claim 1, wherein an inclined layer is formed.   The surface emitting laser according to claim 2, wherein an Al composition interval in the step is small on the active layer side.   The surface emitting laser according to any one of claims 2 to 6, wherein a gap of Al composition between layers or a layer adjacent to the steps is 0.5 or less.   The surface emitting laser according to any one of claims 2 to 7, wherein the unevenness of the interface in the stacking direction of the composition gradient layer is 4 nm or less.   The surface emitting laser according to claim 2, wherein the unevenness of the interface in the stacking direction of the composition gradient layer is 2 nm or less.   The surface emitting laser according to any one of claims 2 to 9, wherein a distance between the Al-containing oxide constriction layer and the active layer is in a range of 40 to 400 nm.   The surface emitting laser according to any one of claims 2 to 10, wherein an In-containing layer is inserted between the Al-containing oxide constriction layer and the active layer. Formed on a III-V compound substrate;
A resonator region comprising an active layer and an Al-containing oxide constriction layer;
A surface-emitting laser comprising a pair of DBR mirrors facing each other so as to sandwich the resonance region,
The DBR mirror is composed of a semiconductor mirror made of an AlGaAs / GaAs pair,
An Al-containing oxide constriction layer is formed on a part of the DBR mirror, and a plurality of steps comprising an Al-containing III-V compound and an Al-free III-V compound are provided on both sides of the Al-containing oxide constriction layer. The plurality of steps form a pseudo-composition gradient layer, the pseudo composition of which is continuously decreasing as the pseudo composition moves away from the Al-containing oxide constriction layer, and the Al-containing oxide A surface emitting laser characterized in that a part thereof is oxidized from an interface adjacent to a constriction layer.   A semiconductor laser element array comprising a plurality of the surface emitting lasers according to claim 1.   An optical apparatus comprising the surface emitting laser according to any one of claims 1 to 12.   A communication system comprising the surface emitting laser according to any one of claims 1 to 13.

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