WO2024095835A1 - Semiconductor laser device, semiconductor laser module, and sensor - Google Patents

Abstract

This semiconductor laser device comprises: an active layer that includes a barrier layer and well layers which are provided respectively on both sides of the barrier layer in the thickness direction of the barrier layer; and an n-type semiconductor layer and a p-type semiconductor layer that sandwich the active layer therebetween in the thickness direction of the barrier layer. The thickness of the well layers is greater than the thickness of the barrier layer.

Description

Semiconductor laser device, semiconductor laser module, and sensor

This disclosure relates to a semiconductor laser device, a semiconductor laser module, and a sensor.

Patent Document 1 discloses a semiconductor laser device. This semiconductor laser device includes a double heterostructure having an n-type cladding layer, an active layer, and a p-type cladding layer. Such a semiconductor laser device emits laser light from an end face of the active layer.

JP 2019-186387 A

Incidentally, it is desirable to reduce the temperature dependency of the wavelength of the laser light from a semiconductor laser device.

A semiconductor laser device according to one aspect of the present disclosure includes an active layer including a barrier layer and well layers provided on both sides of the barrier layer in the thickness direction of the barrier layer, and an n-type semiconductor layer and a p-type semiconductor layer sandwiching the active layer in the thickness direction of the active layer, and the thickness of the well layer is greater than the thickness of the barrier layer.

A semiconductor laser module according to one aspect of the present disclosure includes the semiconductor laser device, a stem to which the semiconductor laser device is attached, a cap attached to the stem, covering the semiconductor laser device and having an opening through which laser light from the semiconductor laser device passes, and a terminal pin electrically connected to the semiconductor laser device.

A sensor according to one aspect of the present disclosure includes the semiconductor laser module, a bandpass filter, and a light receiving module including a light receiving element that receives light that has passed through the bandpass filter.

The above-mentioned semiconductor laser device, semiconductor laser module, and sensor can reduce the temperature dependence of the wavelength of laser light.

FIG. 1 is a perspective view showing a semiconductor laser device according to an embodiment. FIG. 2 is a cross-sectional view of the semiconductor laser device shown in FIG. 1 taken along line F2-F2. FIG. 3 is an explanatory diagram showing an example of the structure of the light-emitting unit shown in FIG. FIG. 4 is an explanatory diagram showing an example of the structure of the active layer shown in FIG. FIG. 5 is an explanatory diagram showing an example of the structure of the tunnel layer shown in FIG. FIG. 6 is a perspective view showing a semiconductor laser module including a semiconductor laser device. FIG. 7 is a cross-sectional view of the semiconductor laser module shown in FIG. FIG. 8 is a plan view showing a semiconductor laser unit on which a semiconductor laser device is mounted. FIG. 9 is a rear view showing the semiconductor laser unit of FIG. FIG. 10 is an explanatory diagram showing an example of the structure of a sensor equipped with a semiconductor laser module. FIG. 11 is a table showing the relationship between the thickness of the well layer and the thickness of the barrier layer and the wavelength temperature coefficient and optical spectrum of the laser light. FIG. 12 is a graph showing the optical spectrum of the emission intensity versus wavelength at temperatures from 10° C. to 90° C. for the semiconductor laser device included in region R of FIG. FIG. 13 is a graph showing optical spectra of emission intensity versus wavelength at temperatures from 10° C. to 90° C. for a semiconductor laser device outside the region R in FIG. FIG. 14 is a table showing the relationship between the well layer thickness and the optical output. FIG. 15 is a table showing the relationship between the emission width of the laser light and the wavelength temperature coefficient. FIG. 16 is a cross-sectional view showing a semiconductor laser device according to a first modified example. FIG. 17 is a cross-sectional view showing a semiconductor laser device according to a second modification. FIG. 18 is a perspective view showing a semiconductor laser module according to a modified example. FIG. 19 is a cross-sectional view of the semiconductor laser module shown in FIG.

Below, embodiments of the semiconductor laser device, semiconductor laser module, and sensor of the present disclosure will be described with reference to the attached drawings. Note that, for simplicity and clarity of explanation, the components shown in the drawings are not necessarily drawn to scale. Also, for ease of understanding, hatched lines may be omitted in cross-sectional views. The attached drawings are merely illustrative of embodiments of the present disclosure and should not be considered as limiting the present disclosure.

The following detailed description includes devices, systems, and methods embodying exemplary embodiments of the present disclosure. The detailed description is merely illustrative in nature and is not intended to limit the embodiments of the present disclosure or the application and uses of such embodiments.

[Configuration of Semiconductor Laser Device]
The configuration of a semiconductor laser device 10 according to one embodiment will be described with reference to FIGS.
Fig. 1 shows a perspective structure of a semiconductor laser device 10, and Fig. 2 shows a cross-sectional structure of the semiconductor laser device of Fig. 1. Fig. 3 shows a schematic example of a structure of the light emitting unit of Fig. 2, Fig. 4 shows a schematic example of a structure of the active layer shown in Fig. 3, and Fig. 5 shows a schematic example of a structure of the tunnel layer of Fig. 2.

As shown in FIGS. 1 and 2, the semiconductor laser device 10 has a semiconductor substrate 20, a light emitting portion 30, an insulating film 70, a first electrode 81, and a second electrode 82.
The semiconductor substrate 20 is formed, for example, in the shape of a rectangular plate. The semiconductor substrate 20 is configured, for example, of an n-type semiconductor substrate (n-GaAs substrate) containing GaAs (gallium arsenide). The semiconductor substrate 20 contains at least one of Si (silicon), Te (tellurium), and Se (selenium) as an n-type impurity.

The semiconductor substrate 20 has a substrate main surface 21, a substrate back surface 22, and substrate side surfaces 23 to 26. The substrate main surface 21 and the substrate back surface 22 face in opposite directions. Hereinafter, the direction perpendicular to the substrate main surface 21 will be referred to as the "Z direction", and the two directions perpendicular to the Z direction will be referred to as the "X direction" and "Y direction", respectively. The Z direction can be said to be the thickness direction of the semiconductor substrate 20. The substrate side surfaces 23 and 24 face in opposite directions in the Y direction, and the substrate side surfaces 25 and 26 face in opposite directions in the X direction. When viewed from the Z direction, the semiconductor substrate 20 is formed in a rectangular shape that is long in the Y direction.

The light emitting portion 30 is provided on a substrate main surface 21 of a semiconductor substrate 20. The light emitting portion 30 protrudes from the substrate main surface 21 toward the side opposite to the substrate back surface 22.
The light emitting unit 30 has an electrode connection surface 31, a substrate connection surface 32, light emitting unit end surfaces 33, 34, and light emitting unit side surfaces 35, 36. The electrode connection surface 31 faces the same direction as the substrate main surface 21 in the Z direction. The electrode connection surface 31 is disposed apart from the substrate main surface 21 in the Z direction. The substrate connection surface 32 faces the semiconductor substrate 20 side and is connected to the substrate main surface 21. The light emitting unit side surfaces 35, 36 face opposite each other in the X direction. The light emitting unit side surfaces 35, 36 connect the electrode connection surface 31 and the substrate main surface 21. The light emitting unit end surfaces 33, 34 face opposite each other in the Y direction. The light emitting unit end surfaces 33, 34 constitute resonator end surfaces. In one example, the light emitting unit 30 emits laser light L1 from the light emitting unit end surface 33.

In this embodiment, the light emitting section 30 has a mesa structure and is formed in a trapezoidal shape (ridge shape) protruding from the substrate main surface 21 when viewed from the Y direction. The light emitting section side surface 35 is inclined so as to face the electrode connection surface 31 side with respect to the direction in which the substrate side surface 25 faces. The light emitting section side surface 36 is inclined so as to face the electrode connection surface 31 side with respect to the direction in which the substrate side surface 26 faces. Therefore, when viewed from the Y direction, the light emitting section 30 is formed in a trapezoidal shape in which the width of the electrode connection surface 31 is narrower than the width of the substrate connection surface 32 that is connected to the substrate main surface 21.

As shown in FIG. 1, the light emitting section 30 extends in the Y direction. In one example, the length of the light emitting section 30 in the Y direction is equal to the length of the semiconductor substrate 20. In other words, the light emitting section end surface 33 of the light emitting section 30 is flush with the substrate side surface 23 of the semiconductor substrate 20, and the light emitting section end surface 34 is flush with the substrate side surface 24 of the semiconductor substrate 20.

The insulating film 70 is formed so as to cover a part of the substrate main surface 21 of the semiconductor substrate 20. The insulating film 70 is also formed so as to cover the light emitting portion 30. In this embodiment, the insulating film 70 is formed so as to cover the electrode connection surface 31 and the light emitting portion side surfaces 35, 36 of the light emitting portion 30. The insulating film 70 of this embodiment has substrate covering portions 72, 73 that cover the substrate main surface 21 of the semiconductor substrate 20, and a light emitting portion covering portion 74 that covers the light emitting portion 30. The insulating film 70 is made of, for example, SiN (silicon nitride), SiO ₂ (silicon oxide), or the like.

As shown in Figures 1 and 2, the first electrode 81 is provided on the upper surface 71 of the insulating film 70 that covers the electrode connection surface 31 of the light-emitting section 30. As shown in Figure 2, the insulating film 70 that covers the electrode connection surface 31 of the light-emitting section 30 has a first opening 71X that exposes a portion of the electrode connection surface 31. The first electrode 81 is electrically connected to the electrode connection surface 31 exposed from the first opening 71X of the insulating film 70. In other words, the first electrode 81 is electrically connected to the light-emitting section 30. The first electrode 81 is formed so as to cover the end that forms the first opening 71X of the insulating film 70.

The first electrode 81 may be composed of multiple electrode layers. In one example, the first electrode 81 includes a first electrode layer and a second electrode layer. The first electrode layer and the second electrode layer are laminated in this order from the electrode connection surface 31 side. The first electrode layer is composed of, for example, Ti (titanium)/Au (gold). The second electrode layer is, for example, a plating layer containing Au.

As shown in Figures 1 and 2, the second electrode 82 is provided on the rear surface 22 of the semiconductor substrate 20. In this embodiment, the second electrode 82 covers the entire rear surface 22 of the substrate. The second electrode 82 is electrically connected to the semiconductor substrate 20.

The second electrode 82 may be composed of multiple electrode layers. In one example, the second electrode 82 may include at least one of a Ni (nickel) layer, an AuGe (gold-germanium alloy) layer, a Ti layer, and an Au layer. In one example, the second electrode 82 may include a Ni layer, an AuGe layer, a Ti layer, and an Au layer stacked in this order from the rear surface 22 of the substrate.

[Light-emitting section]
Next, the detailed configuration of the light-emitting unit 30 will be described.
2, the light-emitting section 30 includes light-emitting units 40 stacked on the substrate main surface 21 of the semiconductor substrate 20. The light-emitting units 40 generate light by recombination of holes and electrons. The light-emitting section 30 of this embodiment has three light-emitting units 40. Note that the light-emitting section 30 may have at least one light-emitting unit 40. In other words, the number of light-emitting units 40 may be one, two, or four or more.

The light-emitting section 30 of this embodiment includes a tunnel layer 60 disposed between adjacent light-emitting units 40. The tunnel layer 60 generates a tunnel current due to the tunnel effect and supplies it to the light-emitting unit 40. The light-emitting section 30 of this embodiment includes two tunnel layers 60. The tunnel layer 60 is disposed between two adjacent light-emitting units 40.

The emission width of the laser light L1 (see FIG. 1) emitted from the light-emitting unit 30 is, for example, 50 μm or more and 300 μm or less. In this embodiment, the emission width is 270 μm. Here, the emission width can be defined by the length in the X direction of the laser light L1 at the light-emitting end surface 33 of the light-emitting unit 30.

FIG. 3 shows an example of the structure of the light-emitting unit 40 .
The light-emitting unit 40 includes an active layer 41, and an n-type semiconductor layer 42 and a p-type semiconductor layer 43 which sandwich the active layer 41 in the thickness direction of the active layer 41. In this embodiment, the thickness direction of the active layer 41 coincides with the Z direction. The light-emitting section end surface 33 of the light-emitting section 30 includes an end surface of the active layer 41. For this reason, it can be said that the active layer 41 includes an end surface that emits laser light.

The n-type semiconductor layer 42 is disposed on the side of the active layer 41 that faces the semiconductor substrate 20 shown in Figures 1 and 2. The p-type semiconductor layer 43 is disposed on the side of the active layer 41 that faces the opposite side to the n-type semiconductor layer 42, that is, on the side of the first electrode 81 shown in Figures 1 and 2. For this reason, it can be said that the light-emitting unit 40 has a layered structure that includes the n-type semiconductor layer 42, the active layer 41, and the p-type semiconductor layer 43, which are layered in this order from the semiconductor substrate 20 side.

The n-type semiconductor layer 42 includes aluminum gallium arsenide (AlGaAs). The n-type semiconductor layer 42 includes at least one of Si, Te, and Se as an n-type impurity. The impurity concentration of the n-type semiconductor layer 42 is, for example, not less than 1×10 ¹⁷ cm ⁻³ and not more than 1×10 ¹⁹ cm ⁻³ .

The n-type semiconductor layer 42 includes a first n-type cladding layer 44 and a second n-type cladding layer 45. The first n-type cladding layer 44 is disposed adjacent to the active layer 41. The second n-type cladding layer 45 is disposed on the opposite side of the active layer 41 with respect to the first n-type cladding layer 44. In other words, it can be said that the n-type semiconductor layer 42 includes the first n-type cladding layer 44 adjacent to the active layer 41, and the second n-type cladding layer 45 located on the opposite side of the active layer 41 with respect to the first n-type cladding layer 44. It can also be said that the n-type semiconductor layer 42 includes the first n-type cladding layer 44 and the second n-type cladding layer 45 stacked in this order from the active layer 41 side.

The first n-type cladding layer 44 includes Al _A1 Ga _(1-A1) As having an Al composition A1. In one example, the Al composition A1 of the first n-type cladding layer 44 is 0.2 or more and 0.5 or less. The second n-type cladding layer 45 includes Al _A2 Ga _(1-A2) As having an Al composition A2 different from the Al composition A1 of the first n-type cladding layer 44. The Al composition A2 of the second n-type cladding layer 45 is larger than the Al composition A1 of the first n-type cladding layer 44 (A2>A1). In one example, the Al composition A2 of the second n-type cladding layer 45 is 0.4 or more and 0.7 or less.

In this embodiment, the impurity concentration of the second n-type cladding layer 45 is different from the impurity concentration of the first n-type cladding layer 44. More specifically, the impurity concentration of the second n-type cladding layer 45 is higher than the impurity concentration of the first n-type cladding layer 44. The impurity concentration of the second n-type cladding layer 45 may be equal to the impurity concentration of the first n-type cladding layer 44. The impurity concentration of the second n-type cladding layer 45 may also be lower than the impurity concentration of the first n-type cladding layer 44.

P-type semiconductor layer 43 includes AlGaAs. P-type semiconductor layer 43 includes p-type impurities, for example, C (carbon). The impurity concentration of p-type semiconductor layer 43 is, for example, not less than 1×10 ¹⁷ cm ⁻³ and not more than 1×10 ¹⁹ cm ⁻³ .

The p-type semiconductor layer 43 includes a first p-type cladding layer 46 and a second p-type cladding layer 47. The first p-type cladding layer 46 is disposed adjacent to the active layer 41. The second p-type cladding layer 47 is disposed on the opposite side of the active layer 41 with respect to the first p-type cladding layer 46. In other words, it can be said that the p-type semiconductor layer 43 includes the first p-type cladding layer 46 adjacent to the active layer 41, and the second p-type cladding layer 47 located on the opposite side of the active layer 41 with respect to the first p-type cladding layer 46. It can also be said that the p-type semiconductor layer 43 includes the first p-type cladding layer 46 and the second p-type cladding layer 47 stacked in this order from the active layer 41 side.

The first p-type cladding layer 46 includes Al _B1 Ga _(1-B1) As having an Al composition B1. In one example, the Al composition B1 of the first p-type cladding layer 46 is 0.2 or more and 0.5 or less. The second p-type cladding layer 47 includes Al _B2 Ga _(1-B2) As having an Al composition B2 different from the Al composition B1 of the first p-type cladding layer 46. The Al composition B2 of the second p-type cladding layer 47 is larger than the Al composition B1 of the first p-type cladding layer 46 (B2>B1). In one example, the Al composition B2 of the second p-type cladding layer 47 is 0.4 or more and 0.7 or less.

In this embodiment, the impurity concentration of the second p-type cladding layer 47 is different from the impurity concentration of the first p-type cladding layer 46. More specifically, the impurity concentration of the second p-type cladding layer 47 is higher than the impurity concentration of the first p-type cladding layer 46. The impurity concentration of the second p-type cladding layer 47 may be equal to the impurity concentration of the first p-type cladding layer 46. The impurity concentration of the second p-type cladding layer 47 may be lower than the impurity concentration of the first p-type cladding layer 46.

FIG. 4 shows an example of the configuration of the active layer 41 .
The active layer 41 includes a barrier layer 51 and well layers 52 provided on both sides of the barrier layer 51 in the thickness direction of the barrier layer 51. The well layer 52 is a quantum well layer, and the barrier layer 51 is a barrier layer that acts as a barrier against the movement of carriers (electrons and holes) between the well layers 52. Here, the thickness direction of the barrier layer 51 coincides with the Z direction. For convenience, the well layers 52 provided on both sides of the barrier layer 51 are referred to as a "first well layer 52A" and a "second well layer 52B". In this case, the active layer 41 has a multiple quantum well structure including the barrier layer 51, the first well layer 52A, and the second well layer 52B.

The first well layer 52A and the second well layer 52B are arranged with the barrier layer 51 in between. The first well layer 52A is arranged adjacent to the barrier layer 51 on the side of the n-type semiconductor layer 42 shown in FIG. 3 with respect to the barrier layer 51. The second well layer 52B is arranged on the opposite side of the barrier layer 51 to the first well layer 52A. In other words, it can be said that the active layer 41 includes the first well layer 52A, the barrier layer 51, and the second well layer 52B, which are stacked in this order from the n-type semiconductor layer 42 (first n-type cladding layer 44) shown in FIG. 3.

The active layer 41 of this embodiment further includes a first guiding layer 53 and a second guiding layer 54 .
The first guide layer 53 is disposed adjacent to the first well layer 52A. The first guide layer 53 is disposed on the opposite side of the barrier layer 51 with respect to the first well layer 52A. The second guide layer 54 is disposed adjacent to the second well layer 52B. The second guide layer 54 is disposed on the opposite side of the barrier layer 51 with respect to the second well layer 52B. It can be said that the first guide layer 53 and the second guide layer 54 are disposed to sandwich the first well layer 52A, the barrier layer 51, and the second well layer 52B. In this embodiment, it can be said that the active layer 41 includes the first guide layer 53, the first well layer 52A, the barrier layer 51, the second well layer 52B, and the second guide layer 54, which are stacked in this order from the n-type semiconductor layer 42 (first n-type cladding layer 44) shown in FIG. 3.

The barrier layer 51 includes AlGaAs. The barrier layer 51 includes Al _C1 Ga _(1-C1) As having an Al composition C1. The Al composition C1 of the barrier layer 51 is different from the Al composition (Al compositions A1, A2) of the n-type semiconductor layer 42 and the Al composition (Al compositions B1, B2) of the p-type semiconductor layer 43. The Al composition C1 of the barrier layer 51 is smaller than the Al composition (Al compositions A1, A2) of the n-type semiconductor layer 42 and the Al composition (Al compositions B1, B2) of the p-type semiconductor layer 43. In one example, the Al composition C1 of the barrier layer 51 is 0.05 or more and 0.3 or less. The barrier layer 51 may be free of impurities.

The first well layer 52A includes In _D1 Ga _(1-D1) As having an In composition D1. In one example, the In composition D1 is greater than 0 and equal to or less than 0.15. The first well layer 52A may be undoped.

The second well layer 52B includes In _D2 Ga _(1-D2) As having an In composition D2. The In composition D2 may be equal to the In composition D1 of the first well layer 52A. In one example, the In composition D2 is greater than 0 and equal to or less than 0.15. The second well layer 52B may be undoped.

The first guide layer 53 includes AlGaAs. The first guide layer 53 includes Al _C2 Ga _(1-C2) As having an Al composition C2. The Al composition C2 of the first guide layer 53 is different from the Al composition (Al compositions A1, A2) of the n-type semiconductor layer 42. The Al composition C2 of the first guide layer 53 is smaller than the Al composition (Al compositions A1, A2) of the n-type semiconductor layer 42. In one example, the Al composition C2 of the first guide layer 53 is 0.05 or more and 0.3 or less. The first guide layer 53 may be free of impurities.

The second guide layer 54 includes AlGaAs. The second guide layer 54 includes Al _C3 Ga _(1-C3) As having an Al composition C3. The Al composition C3 of the second guide layer 54 is different from the Al composition (Al compositions B1, B2) of the p-type semiconductor layer 43. The Al composition C3 of the second guide layer 54 is smaller than the Al composition (Al compositions B1, B2) of the p-type semiconductor layer 43. The Al composition C3 of the second guide layer 54 may be equal to the Al composition C2 of the first guide layer 53. In one example, the Al composition C3 of the second guide layer 54 is 0.05 or more and 0.3 or less. The second guide layer 54 may be free of impurities.

FIG. 5 shows an example of the configuration of the tunnel layer 60 .
The tunnel layer 60 includes a p-type tunnel layer 61 and an n-type tunnel layer 62. The p-type tunnel layer 61 is disposed adjacent to the p-type semiconductor layer 43 (second p-type cladding layer 47) shown in FIG. 3. The n-type tunnel layer 62 is disposed adjacent to the n-type semiconductor layer 42 (second n-type cladding layer 45) shown in FIG. 3. Therefore, the p-type tunnel layer 61 and the n-type tunnel layer 62 are laminated in this order from the side of the semiconductor substrate 20 shown in FIG. 1 and FIG. 2. The tunnel layer 60 is disposed between the light-emitting units 40 in such a manner that the p-type tunnel layer 61 is electrically connected to the p-type semiconductor layer 43 and the n-type tunnel layer 62 is electrically connected to the n-type semiconductor layer 42.

The p-type tunnel layer 61 contains GaAs. The p-type tunnel layer 61 contains, for example, C as a p-type impurity. The impurity concentration of the p-type tunnel layer 61 is different from the impurity concentration of the p-type semiconductor layer 43. The impurity concentration of the p-type tunnel layer 61 is higher than the impurity concentration of the p-type semiconductor layer 43.

The n-type tunnel layer 62 includes GaAs. The n-type tunnel layer 62 includes at least one of the following n-type impurities: Si, Te, and Se. The impurity concentration of the n-type tunnel layer 62 is different from the impurity concentration of the n-type semiconductor layer 42. The impurity concentration of the n-type tunnel layer 62 is higher than the impurity concentration of the n-type semiconductor layer 42.

[Relationship between barrier layer and well layer thickness]
Next, a description will be given of the thickness relationship between the barrier layer 51, the first well layer 52A, and the second well layer 52B. In the following, when a matter common to the first well layer 52A and the second well layer 52B is mentioned, it will be simply referred to as the well layer 52.

The thickness TWA of the first well layer 52A and the thickness TWB of the second well layer 52B are thicker than the thickness TB of the barrier layer 51. In other words, the thickness TW of the well layer 52 is thicker than the thickness TB of the barrier layer 51. In one example, the thickness TWA of the first well layer 52A and the thickness TWB of the second well layer 52B are equal to each other. In one example, the ratio (TW/TB) of the thickness TW of the well layer 52 to the thickness TB of the barrier layer 51 is 1.9 or more and 4.3 or less.

In one example, the thickness TW of the well layer 52 is greater than 100 Å and less than or equal to 130 Å. In one example, the thickness TW of the well layer 52 is greater than or equal to 105 Å and less than or equal to 130 Å. In one example, the thickness TW of the well layer 52 is greater than or equal to 110 Å and less than or equal to 130 Å.

In one example, the thickness TB of the barrier layer 51 is greater than 0 Å and equal to or less than 60 Å. In one example, the thickness TB of the barrier layer 51 is equal to or greater than 30 Å and equal to or less than 60 Å.
As an example of a combination of the thickness TB of the barrier layer 51 and the thickness TW of the well layer 52, the thickness TB of the barrier layer 51 is greater than 0 Å and less than 60 Å, and the thickness TW of the well layer 52 is greater than 100 Å and less than 140 Å. In another example, the thickness TB of the barrier layer 51 is greater than 30 Å and less than 60 Å, and the thickness TW of the well layer 52 is greater than 100 Å and less than 13 ...5 Å and less than 130 Å. In another example, the thickness TB of the barrier layer 51 is greater than 30 Å and less than 60 Å, and the thickness TW of the well layer 52 is greater than 110 Å and less than 130 Å.

[Application examples of semiconductor laser devices]
An example of a semiconductor laser module 200 including the semiconductor laser device 10 will be described with reference to FIGS.

As shown in Figures 6 and 7, the semiconductor laser module 200 includes a stem 210, a semiconductor laser unit 100 mounted on the stem 210, a cap 220 that covers the semiconductor laser unit 100, and terminal pins 231 to 234 that are electrically connected to the semiconductor laser unit 100. The semiconductor laser unit 100 includes a semiconductor laser device 10.

The stem 210 includes a flat base 211 and a heat sink 212 standing on the base 211. The semiconductor laser unit 100 is mounted on the heat sink 212. The cap 220 is attached to the base 211 so as to cover the semiconductor laser unit 100 and the heat sink 212. The cap 220, together with the base 211, forms an accommodation space SP that accommodates the semiconductor laser unit 100 and the heat sink 212. The cap 220, together with the base 211, makes the accommodation space SP (see Figure 7) airtight in a hollow state, forming a hollow sealing structure.

The cap 220 is made of a light-shielding material and has an opening 221 through which the laser light from the semiconductor laser unit 100 passes. In one example, a light-transmitting plate 222 (see FIG. 7) is attached to the opening 221.

Terminal pins 231 to 234 are provided on base 211. More specifically, each of terminal pins 231 to 233 penetrates base 211 in the thickness direction of base 211. Insulating material 235 is filled between terminal pins 231 to 233 and base 211. Terminal pin 234 is formed integrally with base 211.

FIG. 8 shows the planar structure of the semiconductor laser unit 100 in a state where the insulating layer covering the substrate main surface 111 of the substrate 110 is omitted.
As shown in FIG. 8, the semiconductor laser unit 100 includes a substrate 110, and a semiconductor laser device 10, a switching element 120, and capacitors 131 and 132 mounted on the substrate 110.

The substrate 110 is formed in a rectangular flat plate shape. The substrate 110 is formed from an insulating material such as glass epoxy resin. The substrate 110 has a substrate main surface 111 and a substrate back surface 112 (see FIG. 9) facing the opposite side to the substrate main surface 111.

First to third main surface side wirings 111A to 111C are formed on the main surface side wirings of the substrate 110. The semiconductor laser device 10, the switching element 120, and the capacitors 131 and 132 are mounted on the first and second main surface side wirings 111A and 111B.

The semiconductor laser device 10 is bonded to the center of the first main surface side wiring 111A in the X direction by a conductive bonding material SD such as solder paste or Ag (silver) paste. This electrically connects the semiconductor laser device 10 and the first main surface side wiring 111A.

The switching element 120 is a semiconductor element that controls the current supplied to the semiconductor laser device 10. The switching element 120 is, for example, a transistor. In one example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is used as the switching element 120.

A source electrode 121 and a gate electrode 122 are formed on the element principal surface of the switching element 120 facing the same side as the substrate principal surface 111, and a drain electrode (not shown) is formed on the element rear surface facing the substrate principal surface 111. In other words, the switching element 120 is a vertical structure MOSFET. The switching element 120 is joined to the center of the second principal surface side wiring 111B in the X direction by a conductive bonding material SD. This electrically connects the drain of the switching element 120 to the second principal surface side wiring 111B. The source electrode 121 is electrically connected to the semiconductor laser device 10 by a wire W1.

The capacitors 131 and 132 are electronic components that cooperate with the switching element 120 to supply current to the semiconductor laser device 10. The capacitances of the capacitors 131 and 132 are equal to each other. The capacitors 131 and 132 are arranged so as to straddle the first main surface side wiring 111A and the second main surface side wiring 111B. The capacitors 131 and 132 are joined to both the first main surface side wiring 111A and the second main surface side wiring 111B by a conductive bonding material SD. As a result, the capacitors 131 and 132 are electrically connected to both the first main surface side wiring 111A and the second main surface side wiring 111B.

As shown in FIG. 8, the capacitors 131 and 132 are arranged symmetrically with respect to the semiconductor laser device 10 and the switching element 120 on the substrate main surface 111. As a result, a loop-shaped first wiring path through which a current flows from the capacitor 131 to the semiconductor laser device 10 via the switching element 120, and a loop-shaped second wiring path through which a current flows from the capacitor 132 to the semiconductor laser device 10 via the switching element 120 are formed symmetrically with respect to the semiconductor laser device 10 and the switching element 120. In this way, by symmetrically arranging the first wiring path and the second wiring path, the magnetic flux formed by the current flowing through the first wiring path and the magnetic flux formed by the current flowing through the second wiring path cancel each other out. This makes it possible to reduce both the parasitic inductance present in the first wiring path and the parasitic inductance present in the second wiring path.

As shown in FIG. 9, a first back surface side wiring 112A and a second back surface side wiring 112B are formed as back surface side wiring on the back surface 112 of the substrate 110. The first back surface side wiring 112A and the second back surface side wiring 112B constitute the external terminals of the semiconductor laser unit 100.

The first back surface side wiring 112A is electrically connected to both the first main surface side wiring 111A and the third main surface side wiring 111C by one or more through holes 113. The second back surface side wiring 112B is formed at a position overlapping the switching element 120 shown in a dashed line frame in FIG. 9 in a plan view. The first back surface side wiring 112A is formed in a substantially U-shape surrounding the second back surface side wiring 112B. The second back surface side wiring 112B is electrically connected to the second main surface side wiring 111B (see FIG. 8) by one or more through holes 114.

Next, the electrical connection structure between the semiconductor laser unit 100 and the terminal pins 231 to 233 will be described.
6, the terminal pins 231 to 233 protrude from both sides of the base 211 in the thickness direction of the base 211. The portions of the terminal pins 231 to 233 protruding toward the heat sink 212 side from the base 211 are electrically connected to the semiconductor laser unit 100 by wires W2 to W4, respectively. More specifically, the wire W2 electrically connects the terminal pin 231 to the source electrode 121 of the switching element 120. The wire W3 electrically connects the terminal pin 232 to the gate electrode 122 of the switching element 120. The wire W4 electrically connects the terminal pin 233 to the third main surface side wiring 111C.

As shown in FIG. 7, the terminal pin 234 is formed integrally with the base 211 and is therefore electrically connected to the base 211. It can also be said that the terminal pin 234 is electrically connected to the heat sink 212.

The semiconductor laser unit 100 is mounted on the heat sink 212 so that the second back surface side wiring 112B of the substrate 110 is joined to the heat sink 212 by a conductive bonding material. On the other hand, the first back surface side wiring 112A is not electrically connected to the heat sink 212. Therefore, the terminal pin 234 is electrically connected to the drain electrode of the switching element 120.

[Application examples of semiconductor laser modules]
With reference to FIG. 10, a sensor 400 including the semiconductor laser module 200 will be described as an application example of the semiconductor laser module 200.

The sensor 400 can be used as a distance measuring sensor such as LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging), which is an example of three-dimensional distance measurement. The sensor 400 may also be used as a distance measuring sensor for two-dimensional distance measurement.

The sensor 400 includes a semiconductor laser module 200 as an emitting module, and a light receiving module 300. In the sensor 400, the semiconductor laser module 200 emits laser light toward the measurement object MX. The light receiving module 300 receives the laser light (reflected light) reflected by the measurement object MX. The sensor 400 measures the time difference between when the semiconductor laser module 200 emits the laser light and when the light receiving module 300 receives the reflected light. This allows the distance between the sensor 400 and the measurement object MX to be calculated.

The light receiving module 300 includes a light receiving element 310 and a bandpass filter 320. The bandpass filter 320 is a filter configured to transmit light in a specific wavelength range that includes the wavelength of the reflected light. The light receiving element 310 is configured to receive the light that has passed through the bandpass filter 320.

[Action]
The operation of the semiconductor laser device 10 of this embodiment will now be described.
When a sensor used as a distance measuring sensor as LiDAR is used outdoors, the light receiving element receives sunlight as well as the reflected light shown in Fig. 10. In this case, there is a risk that the received sunlight may be erroneously recognized as reflected light.

In consideration of these problems, the light receiving module 300 of this embodiment is equipped with a bandpass filter 320 that transmits light in a specific wavelength range. In other words, the bandpass filter 320 is configured to include the wavelength of the reflected light in the specific wavelength range. This bandpass filter 320 removes light other than the specific wavelength range from the light receiving element 310. It is preferable that such a bandpass filter 320 has a narrow light transmission width (transmitting wavelength range).

The laser light from a semiconductor laser device has wavelength temperature dependency, in which the central wavelength of the laser light (the wavelength at the peak of the optical spectrum) changes depending on the temperature of the semiconductor laser device. Specifically, the wavelength of the laser light shifts to the longer wavelength side as the temperature increases.

As described above, since laser light has a high wavelength-temperature dependency, the bandpass filter 320 needs to transmit laser light (reflected light) whose wavelength changes within a certain temperature range. For this reason, it is necessary to widen the transmission wavelength range width of the bandpass filter 320. Sunlight contains light of various wavelengths. Therefore, if the transmission wavelength range width of the bandpass filter 320 is widened, more sunlight will pass through the bandpass filter 320, increasing the risk of the sunlight being mistaken for reflected light.

In the semiconductor laser device 10 of this embodiment, the thickness TW of the well layer 52, which is a quantum well layer, is thicker than the thickness TB of the barrier layer 51. This weakens the quantum size effect, making it possible to widen the available energy range. In other words, the spectral width of the laser light that can be oscillated in the well layer 52 can be increased. On the other hand, since the energy and the wavelength are inversely related, oscillation occurs at a short wavelength at high energy. This allows the semiconductor laser device 10 to oscillate a short-wavelength laser light corresponding to high energy. Since such a semiconductor laser device 10 attempts to oscillate a short-wavelength laser light even when the temperature is high, the change in the wavelength of the laser light due to temperature change is suppressed. Therefore, the amount of change (shift) in the wavelength of the laser light due to temperature change is reduced. As a result, the wavelength temperature dependency of the laser light is reduced.

The operation of this semiconductor laser device 10 can be considered as follows. Increasing the thickness TW of the well layer 52 (quantum well layer) weakens the quantum size effect of the quantum well layer, and increases the number of energy levels that can be taken in the well layer 52. Increasing the thickness TW of the well layer 52 weakens the quantum size effect, and the energy width in the well layer 52 can be expanded. When carriers accumulate in the well layer 52, high-energy oscillation occurs, and the well layer 52 emits laser light with a short wavelength in the spectral width. Therefore, this semiconductor laser device 10 attempts to maintain oscillation in the short-wavelength wavelength range by using energy density, even when the temperature becomes high.

As described above, if the thickness TW of the well layer 52 is increased, there is a risk of bias in the carriers (electrons and holes) in the first well layer 52A and the second well layer 52B arranged on both sides of the barrier layer 51. As a result, there is a risk of multiple peaks in the optical spectrum of the laser light (see FIG. 13).

Therefore, in the semiconductor laser device 10 of this embodiment, the thickness TB of the barrier layer 51 is made thin. In one example, the thickness TB of the barrier layer 51 is thinner than the thickness TW of the well layer 52. When the thickness TB of the barrier layer 51 is made thin, carriers can move more easily between the quantum well layers (the first well layer 52A and the second well layer 52B) on both sides of the barrier layer 51 due to the resonant tunneling effect. This reduces the bias of carriers in the first well layer 52A and the second well layer 52B, thereby suppressing the occurrence of multiple peaks in the optical spectrum of the laser light.

(Experimental Example 1)
As Experimental Example 1, the relationship between the thickness TB of the barrier layer 51 and the thickness TW of the well layer 52 of the semiconductor laser device 10 and the wavelength temperature dependency of the semiconductor laser device 10 and the optical spectrum of the laser light was confirmed.

FIG. 11 is a table showing the relationship between the wavelength temperature coefficient (nm/°C) and the state of the optical spectrum of the laser light for a number of semiconductor laser devices 10 in which the thickness TB of the barrier layer 51 and the thickness TW of the well layer 52 are changed. FIGS. 12 and 13 show the optical spectrum of the semiconductor laser device 10 in the case temperature range of 10°C to 90°C. FIG. 12 shows the optical spectrum of the semiconductor laser device 10 included in the region R of FIG. 11. FIG. 13 shows the optical spectrum of the semiconductor laser device 10 outside the region R of FIG. 11. Note that in FIGS. 12 and 13, the optical spectrum at each temperature is shown with the peak emission intensity set to 100%. The case temperature is the temperature of the base 211 of the semiconductor laser module 200. In Experimental Example 1, the emission width is set to 270 μm.

The wavelength temperature coefficient measured in Experimental Example 1 is a coefficient that indicates how much the wavelength changes when the temperature changes by 1°C. The wavelength temperature coefficient is calculated as follows. That is, for example, the amount of change in wavelength when the case temperature is changed over a preset range (set temperature range) is calculated. The wavelength temperature coefficient is calculated by dividing this amount of change in wavelength by the set temperature range. For example, if the set temperature range is 10°C to 90°C and the amount of change in wavelength within this set temperature range is 8 nm, then the coefficient is 0.1 nm/°C.

In experimental example 1, the conditions are that the wavelength temperature coefficient is 0.12 nm/°C or less when the case temperature is in the range of 25°C to 90°C (condition 1), and that the optical spectrum of the laser light does not have multiple peaks (condition 2). In Figure 11, the optical spectrum state that satisfies condition 2 is marked with a "o" and that that does not satisfy condition 2 is marked with an "x". By satisfying conditions 1 and 2, laser light with small wavelength temperature dependency and a single optical spectrum peak is obtained.

As shown in FIG. 11, when the thickness TW of the well layer 52 is thinner than the thickness TB of the barrier layer 51 (the thickness TW of the well layer 52 is 70 Å and the thickness TB of the barrier layer 51 is 90 Å), the wavelength temperature coefficient is 0.18 nm/°C, which is the largest in the table of FIG. 11. In other words, when the thickness TW of the well layer 52 is thicker than the thickness TB of the barrier layer 51, the wavelength temperature coefficient is small.

The region R enclosed by the thick line frame in FIG. 11 is the thickness TB of the barrier layer 51 and the thickness TW of the well layer 52 that satisfy both conditions 1 and 2. Specifically, the thickness TB of the barrier layer 51 is 30 Å or more and 60 Å or less, and the thickness TW of the well layer 52 is greater than 100 Å and less than 130 Å. The thickness TB of the barrier layer 51 may be greater than 20 Å and less than 90 Å.

In this region R, if the thickness TB of the barrier layer 51 is 30 Å or more and 60 Å or less, and the thickness TW of the well layer 52 is 110 Å or more and 125 Å or less, the wavelength temperature coefficient is 0.1 nm/°C or less, and the wavelength temperature dependence of the semiconductor laser device 10 is relatively small. Also, if the thickness TB of the barrier layer 51 is 40 Å or more and 50 Å or less, and the thickness TW of the well layer 52 is 120 Å or more and 125 Å or less, the wavelength temperature coefficient is 0.06 to 0.07 nm/°C, and the wavelength temperature dependence of the semiconductor laser device 10 is relatively small. Also, if the thickness TB of the barrier layer 51 is 40 Å and the thickness TW of the well layer 52 is 120 Å, the wavelength temperature coefficient is 0.06 nm/°C, and the wavelength temperature dependence of the semiconductor laser device 10 is even smaller. Furthermore, if the thickness TB of the barrier layer 51 is 50 Å and the thickness TW of the well layer 52 is 125 Å, the wavelength temperature coefficient is 0.06 nm/°C, so the wavelength temperature dependence of the semiconductor laser device 10 becomes smaller.

Figure 12 shows the optical spectrum of the semiconductor laser device 10 in Experimental Example 1 shown in the table of Figure 11, where the thickness TW of the well layer 52 is 115 Å and the thickness TB of the barrier layer 51 is 30 Å. In this semiconductor laser device 10, the optical spectrum has one peak when the case temperature is between 10°C and 90°C.

Figure 13 shows the optical spectrum of the semiconductor laser device 10 in Experimental Example 1 shown in the table of Figure 11, where the thickness TW of the well layer 52 is 120 Å and the thickness TB of the barrier layer 51 is 90 Å. In this semiconductor laser device 10, when the case temperature is between 75°C and 90°C, the optical spectrum has multiple peaks. Furthermore, the wavelength of the peak shifts to the longer wavelength side as the case temperature increases from 10°C to 75°C, whereas at 85°C and 90°C, the wavelength is shorter than the peak wavelength at 10°C.

(Experimental Example 2)
As Experimental Example 2, the relationship between the thickness TW of the well layer 52 of the semiconductor laser device 10 and the optical output was confirmed. Fig. 14 is a table showing the change in optical output when the thickness TW of the well layer 52 is made thicker than 70 Å, with the optical output being 100% when the thickness TW of the well layer 52 is 70 Å.

As shown in FIG. 14, when the thickness TW of the well layer 52 is in the range of 100 Å or more and 130 Å or less, the light output is 100% or more. On the other hand, when the thickness TW of the well layer 52 is 140 Å, the light output is less than half, at 43%. For this reason, it is preferable that the thickness TW of the well layer 52 is less than 140 Å. More preferably, the thickness TW of the well layer 52 is 130 Å or less.

(Experimental Example 3)
In Experimental Example 3, the relationship between the emission width of the laser light and the wavelength temperature coefficient of the semiconductor laser device 10 was confirmed. In Fig. 15, the thickness TW of the well layer 52 of the semiconductor laser device 10 is 115 Å, and the thickness TB of the barrier layer 51 is 30 Å. In Experimental Example 3, the wavelength temperature coefficient is calculated in a case temperature range of 25°C or more and 90°C or less.

As shown in FIG. 15, when the emission width of the laser light is in the range of 50 μm to 300 μm, the wavelength temperature coefficient is 0.06 nm/°C to 0.08 nm/°C, and is 0.1 nm or less. More specifically, the wavelength temperature coefficient when the emission width is 50 μm is 0.06 nm/°C, the wavelength temperature coefficient when the emission width is 130 μm is 0.07 nm/°C, the wavelength temperature coefficient when the emission width is 225 μm is 0.08 nm/°C, the wavelength temperature coefficient when the emission width is 270 μm is 0.07 nm/°C, the wavelength temperature coefficient when the emission width is 290 μm is 0.06 nm/°C, and the wavelength temperature coefficient when the emission width is 300 μm is 0.06 nm/°C. In this way, if the emission width is 50 μm or 290 μm to 300 μm, the wavelength temperature coefficient is 0.06 nm/°C, and the wavelength temperature dependency of the semiconductor laser device 10 is smaller.

Furthermore, for each of the semiconductor laser devices 10 with laser light emission widths of 50 μm, 130 μm, 225 μm, 270 μm, 290 μm, and 300 μm, the optical spectrum had one peak when the case temperature was in the range of 25°C or higher and 90°C or lower.

[effect]
According to the semiconductor laser device 10, the semiconductor laser module 200, and the sensor 400 of this embodiment, the following effects can be obtained.

(1) The semiconductor laser device 10 includes an active layer 41 including a barrier layer 51 and well layers 52 provided on both sides of the barrier layer 51 in the Z direction, which is the thickness direction of the barrier layer 51, and an n-type semiconductor layer 42 and a p-type semiconductor layer 43 that sandwich the active layer 41 in the Z direction. The thickness TW of the well layer 52 is thicker than the thickness TB of the barrier layer 51. With this configuration, the wavelength temperature dependence of the semiconductor laser device 10 can be reduced by increasing the thickness TW of the well layer 52.

(2) The thickness TW of the well layer 52 is greater than 100 Å and less than 140 Å. With this configuration, the thickness TW of the well layer 52 is greater than 100 Å, so the wavelength temperature dependency of the semiconductor laser device 10 can be reduced. In addition, the thickness TW of the well layer 52 is less than 140 Å, so the decrease in optical output can be suppressed.

(3) The thickness TW of the well layer 52 is 110 Å or more and 130 Å or less. The thickness TB of the barrier layer 51 is 30 Å or more and 60 Å or less. With this configuration, the wavelength temperature coefficient can be made 0.12 nm/°C or less, and the optical spectrum of the laser light can have one peak.

(4) The active layer 41 is configured so that the emission width at its end face (light-emitting portion end face 33) is 50 μm or more and 300 μm or less. The well layer 52 in the active layer 41 has a thickness TW of 115 Å, and the barrier layer 51 has a thickness TB of 30 Å. With this configuration, the wavelength temperature coefficient can be made 0.1 nm/°C or less, and the optical spectrum of the laser light can have one peak.

(5) The semiconductor laser module 200 includes a semiconductor laser device 10, a stem 210 to which the semiconductor laser device 10 is attached, a cap 220 attached to the stem 210, covering the semiconductor laser device 10 and having an opening 221 through which the laser light from the semiconductor laser device 10 passes, and terminal pins 231-234 electrically connected to the semiconductor laser device 10. With this configuration, the semiconductor laser device 10 is attached to the stem 210, so that heat from the semiconductor laser device 10 can be efficiently dissipated to the outside. In addition, by using the semiconductor laser unit 100 including the semiconductor laser device 10 and the switching element 120, the semiconductor laser device 10 can be turned on and off at high speed, and the laser light can be easily pulsed.

(6) The sensor 400 includes a semiconductor laser module 200, a bandpass filter 320, and a light receiving module 300 that receives light that has passed through the bandpass filter 320. With this configuration, the use of a semiconductor laser device 10 with small wavelength temperature dependency makes it possible to narrow the light transmission width of the bandpass filter 320. Therefore, the bandpass filter 320 transmits the laser light of the semiconductor laser device 10 but is less likely to transmit sunlight, thereby suppressing erroneous recognition by the sensor 400. This makes it possible to improve the measurement accuracy of the sensor 400.

<Example of change>
The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other as long as they are not technically inconsistent.

The configuration of the semiconductor laser device 10 of the above embodiment may be modified as appropriate.
FIG. 16 shows a semiconductor laser device 10 according to a first modified example.
In this semiconductor laser device 10, the first electrode 81 extends from the electrode connection surface 31 of the light emitting portion 30 to the substrate covering portion 73 of the insulating film 70 that covers the substrate main surface 21. In this manner, the semiconductor laser device 10 can be driven by connecting a pillar, a wire, or the like to the first electrode 81 extending to the substrate main surface 21.

FIG. 17 shows a semiconductor laser device 10 according to a second modification.
In this semiconductor laser device 10, like the semiconductor laser device 10 of the first modification shown in FIG. 16, the semiconductor laser device 10 has a first electrode 81 extending from the electrode connection surface 31 of the light emitting portion 30 to the substrate covering portion 73 of the insulating film 70 covering the substrate main surface 21. Furthermore, the semiconductor laser device 10 of the second modification has a second opening 72X in the substrate covering portion 72 of the insulating film 70, which exposes a part of the substrate main surface 21 of the semiconductor substrate 20. The second electrode 82 is electrically connected to the semiconductor substrate 20 exposed from the second opening 72X of the insulating film 70. The light emitting portion 30 is connected to the substrate main surface 21 of the semiconductor substrate 20. That is, the second electrode 82 is electrically connected to the light emitting portion 30 via the semiconductor substrate 20. In this way, the semiconductor laser device 10 of the second modification can be driven by the first electrode 81 and the second electrode 82 arranged on the substrate main surface 21 side. Furthermore, since the first electrode 81 and the second electrode 82 are on the main surface 21 side of the substrate, it is possible to connect wires or the like from the same direction, or to perform flip-chip mounting using pillars or the like.

In addition, in the semiconductor laser device 10 of the second modified example, the shape of the first electrode 81 can be the same as the shape of the first electrode 81 of the semiconductor laser device 10 of the above embodiment. In addition, the shapes of the first electrode 81 and the second electrode 82 can be changed as appropriate.

In the above embodiment, an example was described in which the light-emitting section 30 includes three light-emitting units 40 and two tunnel layers 60. However, the number of light-emitting units 40 is arbitrary and is not limited to three. The light-emitting section 30 may have one, two, or four or more light-emitting units 40. In addition, the number of tunnel layers 60 is adjusted according to the number of light-emitting units 40 and is not limited to two.

- In the above embodiment, the capacitors 131 and 132 may be omitted from the semiconductor laser unit 100. Also, the switching element 120 may be omitted from the semiconductor laser unit 100.

- In the above embodiment, the semiconductor laser module 200 has a CAN package structure in which the semiconductor laser unit 100 is attached to the stem 210 and covered by the cap 220, but the configuration of the semiconductor laser module 200 is not limited to this. Instead of the stem 210, the cap 220, and the terminal pins 231 to 234, the semiconductor laser module 200 may have a light-transmitting sealing resin that seals the semiconductor laser device 10, the switching element 120, and the capacitors 131 and 132 on the substrate 110. In this case, the semiconductor laser module 200 has a surface-mount type package structure.

- The semiconductor laser module 200 of the above embodiment may be configured to include only the semiconductor laser device 10. For example, as shown in FIG. 18 and FIG. 19, the semiconductor laser module may be configured in which the semiconductor laser device 10 is mounted on the heat sink 212 of the stem 210 using a submount 140. The submount 140 is a support and a heat sink for the semiconductor laser device 10. The submount 140 is formed of, for example, silicon or aluminum nitride. The submount 140 is formed with a conductive path (not shown) such as a wiring pattern or a through hole for conducting the semiconductor laser device 10 and the heat sink 212. The cap 220 is attached to the base 211 while covering the heat sink 212, the submount 140, and the semiconductor laser device 10. The cap 220 has a transparent plate 222 attached to the opening 221 as in the above embodiment. The semiconductor laser device 10 may be directly mounted on the heat sink 212.

In addition, the modified semiconductor laser module 200 has three terminal pins 236-238 instead of the four terminal pins 231-234. Terminal pin 236 is a terminal pin that is electrically connected to the semiconductor laser device 10 via wire W5. Terminal pin 237 is a terminal pin that is in an electrically floating state in the modified semiconductor laser module 200. Terminal pin 238 is a terminal pin that is connected to the base 211.

In this specification, "at least one of A and B" should be understood to mean "A only, or B only, or both A and B."
The term "on" as used in this disclosure includes both the meanings of "on" and "above" unless the context clearly indicates otherwise. Thus, the expression "a first member is formed on a second member" is intended to mean that in some embodiments, the first member may be directly disposed on the second member in contact with the second member, while in other embodiments, the first member may be disposed above the second member without contacting the second member. In other words, the term "on" does not exclude a structure in which another member is formed between the first member and the second member.

The Z direction used in this disclosure does not necessarily have to be the vertical direction, nor does it have to completely coincide with the vertical direction. Thus, the various structures according to this disclosure are not limited to the "up" and "down" of the Z direction described in this specification being "up" and "down" in the vertical direction. For example, the X direction may be the vertical direction, or the Y direction may be the vertical direction.

<Additional Notes>
The technical ideas that can be understood from the above-mentioned embodiment and modified examples are described below. Note that, for the configurations described in the appendices, the corresponding symbols in the embodiment are shown in parentheses in order to aid in understanding, not to limit the scope of the invention. The symbols are shown as examples to aid in understanding, and the components described in each appendix should not be limited to the components indicated by the symbols.

[Appendix 1]
An active layer (41) including a barrier layer (51) and well layers (52) provided on both sides of the barrier layer (51) in a thickness direction (Z direction) of the barrier layer (51);
an n-type semiconductor layer (42) and a p-type semiconductor layer (43) sandwiching the active layer (41) in a thickness direction (Z direction) of the active layer (41);
A semiconductor laser device (10), wherein the well layer (52) has a thickness (TW) greater than a thickness (TB) of the barrier layer (51).

[Appendix 2]
2. The semiconductor laser device according to claim 1, wherein the well layer (52) has a thickness (TW) greater than 100 Å and less than 140 Å.

[Appendix 3]
3. The semiconductor laser device according to claim 2, wherein the well layer (52) has a thickness (TW) of 110 Å or more and 130 Å or less.

[Appendix 4]
4. The semiconductor laser device according to claim 1, wherein the barrier layer (51) has a thickness (TB) of more than 0 Å and not more than 60 Å.

[Appendix 5]
5. The semiconductor laser device according to claim 4, wherein the barrier layer (51) has a thickness (TB) of 30 Å or more and 60 Å or less.

[Appendix 6]
The active layer (41) includes an end face (33) for emitting light, and is configured to have an emission width at the end face (33) of 270 μm.

[Appendix 7]
The active layer (41) includes an end face (33) for emitting light, and is configured to have an emission width at the end face (33) of 50 μm or more and 300 μm or less.

[Appendix 8]
8. The semiconductor laser device according to claim 7, wherein the well layer (52) has a thickness (TW) of 115 Å and the barrier layer (51) has a thickness (TB) of 30 Å.

[Appendix 9]
The well layer (52) is
a first well layer (52A) adjacent to the barrier layer (51);
a second well layer (52B) disposed on the opposite side of the barrier layer (51) to the first well layer (52A);
The active layer (41) is
a first guide layer (53) sandwiched between the first well layer (52A) and the n-type semiconductor layer (42);
9. The semiconductor laser device according to claim 1, further comprising a second guide layer (54) sandwiched between the second well layer (52B) and the p-type semiconductor layer (43).

[Appendix 10]
The n-type semiconductor layer (42) is
a first n-type cladding layer (44) adjacent to the active layer (41);
a second n-type cladding layer (45) disposed on the opposite side of the first n-type cladding layer (44) to the active layer (41);
The p-type semiconductor layer (43) is
a first p-type cladding layer (46) adjacent to the active layer (41);
A second p-type cladding layer (47) disposed on the opposite side of the first p-type cladding layer (46) to the active layer (41).

[Appendix 11]
The semiconductor laser device according to any one of claims 1 to 10, wherein a plurality of light-emitting units (40) including the active layer (41), the n-type semiconductor layer (42), and the p-type semiconductor layer (43) are stacked in a thickness direction (Z direction) of the active layer (41).

[Appendix 12]
The semiconductor laser device according to claim 11, wherein the plurality of light emitting units (40) are stacked with a tunnel layer (60) interposed therebetween.

[Appendix 13]
A semiconductor laser device (10) according to any one of appendices 1 to 12;
a stem (210) on which the semiconductor laser device (10) is attached;
a cap (220) attached to the stem (210), covering the semiconductor laser device (10) and having an opening (221) through which laser light from the semiconductor laser device (10) passes;
A semiconductor laser module (200) comprising terminal pins (231 to 234) electrically connected to the semiconductor laser device (10).

[Appendix 14]
A semiconductor laser module (200) according to claim 13;
A sensor (400) comprising a light receiving module (300) including a bandpass filter (320) and a light receiving element (310) that receives light that has passed through the bandpass filter (320).

The above description is merely illustrative. Those skilled in the art may recognize that many more possible combinations and permutations are possible other than the components and methods (manufacturing processes) enumerated for purposes of describing the technology of the present disclosure. The present disclosure is intended to embrace all alternatives, modifications, and variations that are within the scope of the present disclosure, including the claims and appendices.

REFERENCE SIGNS LIST 10...Semiconductor laser device 20...Semiconductor substrate 21...Substrate main surface 22...Substrate back surface 23-26...Substrate side surface 30...Light emitting portion 31...Electrode connection surface 32...Substrate connection surface 33, 34...Light emitting portion end surface 35, 36...Light emitting portion side surface 40...Light emitting unit 41...Active layer 42...n-type semiconductor layer 43...p-type semiconductor layer 44...First n-type cladding layer 45...Second n-type cladding layer 46...First p-type cladding layer 47...Second p-type cladding layer 51...Barrier layer 52...Well layer 52A...First well layer 52B...Second well layer 53...First guide layer 54...Second guide layer 60...Tunnel layer 61...p-type tunnel layer 62...n-type tunnel layer 70...Insulating film 71...Upper surface 71X...First opening 72, 73...Substrate covering portion 72X...second opening 74...light emitting portion covering portion 81...first electrode 82...second electrode 100...semiconductor laser unit 110...substrate 111...substrate main surface 111A-111C...first to third main surface side wiring 112...substrate back surface 112A...first back surface side wiring 112B...second back surface side wiring 113, 114...through hole 120...switching element 121...source electrode 122...gate electrode 131, 132...capacitor 140...submount 200...semiconductor laser module 210...stem 211...base 212...heat sink 220...cap 221...opening 222...translucent plate 231-234, 236-238...terminal pin 235...insulating material 300...light receiving module 310...light receiving element 320...bandpass filter 400...sensor R...area L1...laser light SD...conductive bonding material SP...accommodation space TB...barrier layer thickness TW, TWA, TWB...well layer thickness W1 to W5...wires

Claims (14)

1. an active layer including a barrier layer and well layers provided on both sides of the barrier layer in a thickness direction of the barrier layer;
   an n-type semiconductor layer and a p-type semiconductor layer sandwiching the active layer in a thickness direction of the active layer,
   the well layer is thicker than the barrier layer.
2. 2. The semiconductor laser device according to claim 1, wherein the well layer has a thickness greater than 100 Å and less than 140 Å.
3. 3. The semiconductor laser device according to claim 2, wherein the well layer has a thickness of 110 Å or more and 130 Å or less.
4. 4. The semiconductor laser device according to claim 1, wherein the barrier layer has a thickness greater than 0 Å and equal to or less than 60 Å.
5. 5. The semiconductor laser device according to claim 4, wherein the barrier layer has a thickness of 30 Å or more and 60 Å or less.
6. 6. The semiconductor laser device according to claim 1, wherein the active layer includes an end face for emitting light, and is configured so that an emission width at the end face is 270 μm.
7. 6. The semiconductor laser device according to claim 1, wherein the active layer includes an end face for emitting light, and the end face has an emission width of 50 μm or more and 300 μm or less.
8. 8. The semiconductor laser device according to claim 7, wherein the well layer has a thickness of 115 Å, and the barrier layer has a thickness of 30 Å.
9. The well layer is
   a first well layer adjacent to the barrier layer;
   a second well layer disposed on an opposite side of the barrier layer from the first well layer;
   Including,
   The active layer is
   a first guide layer sandwiched between the first well layer and the n-type semiconductor layer;
   a second guide layer sandwiched between the second well layer and the p-type semiconductor layer;
   9. The semiconductor laser device according to claim 1, further comprising:
10. The n-type semiconductor layer is
    a first n-type cladding layer adjacent to the active layer;
    a second n-type cladding layer disposed on an opposite side of the first n-type cladding layer from the active layer;
    Including,
    The p-type semiconductor layer is
    a first p-type cladding layer adjacent to the active layer;
    a second p-type cladding layer disposed on an opposite side of the first p-type cladding layer from the active layer;
    10. The semiconductor laser device according to claim 1, further comprising:
11. 11. The semiconductor laser device according to claim 1, wherein a plurality of light-emitting units, each including the active layer, the n-type semiconductor layer, and the p-type semiconductor layer, are stacked in a thickness direction of the active layer.
12. The semiconductor laser device according to claim 11 , wherein the plurality of light emitting units are stacked with a tunnel layer interposed therebetween.
13. A semiconductor laser device according to any one of claims 1 to 12,
    a stem on which the semiconductor laser device is attached; and
    a cap attached to the stem, covering the semiconductor laser device and having an opening through which laser light from the semiconductor laser device passes;
    a terminal pin electrically connected to the semiconductor laser device;
    A semiconductor laser module comprising:
14. The semiconductor laser module according to claim 13 ;
    a light receiving module including a bandpass filter and a light receiving element that receives light that has passed through the bandpass filter;
    A sensor comprising:

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