JP4800985B2 - Surface emitting laser element, surface emitting laser array including the same, optical scanning device including the surface emitting laser array, and electrophotographic apparatus including the optical scanning device - Google Patents

Description

  The present invention relates to a surface emitting laser element, a surface emitting laser array including the surface emitting laser element, an optical scanning apparatus including the surface emitting laser array, and an electrophotographic apparatus including the optical scanning apparatus.

  Surface-emitting lasers consume less power than end-face lasers, have excellent mode stability, and are easy to integrate, so they are expected to be applied in the communication and image recording fields in recent years. Research and development is in progress.

  In a semiconductor laser, the oscillation wavelength is determined by the band gap of the active layer material, but AlGaAs, (Al) GaInP, (Al) GaInP-based materials, and the like have been studied in the visible region to the near infrared region. Among them, many research reports have been made on AlGaAs-based materials since ancient times, and the characteristics of single-mode output exceeding 3 mW have been obtained for surface-emitting laser elements as reported in Non-Patent Document 1. , Products using the same have already been commercialized.

  However, in semiconductor lasers, Al is considered to be one of the causes of element deterioration, and AlGaAs-based materials inherently have causes of deterioration, so it is difficult to obtain a highly reliable element. On the other hand, since GaInP and GaInAsP-based materials do not contain Al in the active layer, it is relatively easy to obtain a highly reliable element.

On the other hand, the surface emitting laser element has a structure in which the upper and lower sides of a resonator are sandwiched between multilayer films made of two kinds of materials having different refractive indexes. A combination of the two kinds of materials is Al _x Ga _1-x As / Al. _{y Ga 1-y As, (} Al x Ga 1-x) 0.5 In 0.5 P / (Al x Ga 1-x) 0.5 In 0.5 P, Al x Ga 1-x As / ( Al _y Ga _1-y ) _0.5 In _0.5 P (0 ≦ x, y ≦ 1, x ≠ y) is considered, and these material systems and compositions are appropriately set according to the oscillation wavelength. .

  In addition, the surface-emitting laser element has a feature that the element resistance is high due to its structure, and heat generated in the active layer is hardly released to the outside. In other words, in order to develop a surface emitting laser element with good characteristics, it is necessary to solve these problems.For the former, a composition gradient layer is set at the interface between two kinds of materials constituting the reflecting mirror, For the latter, a method such as using a material having excellent thermal conductivity is used.

Regarding the thermal conductivity of the material, if the Al composition is the same, the AlGaAs-based material is superior in thermal conductivity to the AlGaInP-based material, and Non-Patent Document 2 discloses AlAs / Al _0.25 Ga _0.75. A surface emitting laser element using As has been reported.

However, in this report example, (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P is used as a resonator spacer, and this material constitutes a reflector _0.25 Ga _0. It is joined to ₇₅ As. However, the band discontinuity of the valence band of these materials is relatively large, and there is a high possibility of causing an increase in device resistance.

  An example in which an AlGaAs-based reflecting mirror and an AlGaInP-based resonator are joined is described in Non-Patent Document 3, but neither can avoid the same adverse effects.

Further, when the AlGaInP-based material and the AlGaAs-based material are continuously crystal-grown, it is necessary to switch the group V material from the P material (PH ₃ or the like) to the As material (AsH ₃ or the like) after the growth of the AlGaInP material. However, at this time, there is a high possibility that defects are introduced into these interfaces, causing various problems. In Patent Document 1, although there is little possibility of causing the increase in the element resistance, there is no description regarding the P-based / As-based material interface.

  On the other hand, Patent Document 2 shows an example in which only the n-side reflecting mirror or both the p and n-reflecting mirrors are made of an AlGaInP-based material, but the AlGaInP-based material has an AlGaAs-based material with thermal conductivity. Therefore, the temperature of the active layer during oscillation is likely to rise, causing many deteriorations in characteristics.

  On the other hand, in image recording in electrophotography, an image recording method using a laser is widely used as an image recording means for obtaining high-definition image quality. In the case of electrophotography, a method is generally used in which a latent image is formed by rotating a drum (sub-scanning) while scanning a laser (main scanning) using a polygon mirror in the axial direction of a photosensitive drum.

  In the field of electrophotography, high definition of images and high speed of image recording are required. As a method for realizing this, a method of increasing the speed of both main scanning and sub-scanning and increasing the output of the laser or increasing the sensitivity of the photosensitive member can be considered, but this method can improve the image recording speed. There are many problems such as the development of a light source or a high-sensitivity photosensitive member accompanying an increase in the output of the laser, the reinforcement of the housing that supports it by increasing the speed of main / sub scanning, and the development of a position control method during high-speed scanning. Occurs and requires significant cost and time. In addition, when the resolution of an image is doubled for high definition of the image, twice the time is required in both the main scanning and sub-scanning directions. Therefore, four times the time is required for image output. Therefore, in order to achieve high definition of images, it is necessary to simultaneously achieve high speed image output.

  As another method for achieving high-speed image output, a method of using a multi-beam laser is conceivable. In a current high-speed output machine, a plurality of lasers are generally used. By converting the laser into a multi-beam, the area in which the latent image is formed in one main scan is enlarged, and when n lasers are used as compared with the case where one laser is used, The latent image forming area is n times, and the time required for image recording is 1 / n.

  As such an example, a multi-beam semiconductor laser having a plurality of light-emitting light sources in one chip is proposed in Patent Document 3, but in a configuration using an edge-emitting semiconductor laser as described in the invention, Due to structural and cost problems, the limit is about 4 beams or 8 beams, and it is not possible to cope with the speeding up of image output that will be developed in the future.

  On the other hand, as described above, the surface emitting laser element can be easily two-dimensionally integrated, and by devising the integration method, the actual beam pitch can be set narrower and more light emitting elements can be used. It can be integrated on one chip.

JP 2004-281968 A JP 2002-158406 A JP 11-340570 A IEEE PHOTOTONICS TECHNOLOGY LETTERS, VOL. 11, NO. 12, DECENBER 1999 p1539-. ELECTRONICS LETTERS VOL. 31, NO. 7, MARCH 1995. IEEE PHOTOTONICS TECHNOLOGY LETTERS, VOL. 6, NO. 12, DECEMBER 1994 p1397-.

  However, the conventional surface emitting laser device has problems that carrier confinement is insufficient, heat generated in the active layer is difficult to escape to the outside, and output is low.

  Accordingly, the present invention has been made to solve such a problem, and an object thereof is to provide a surface emitting laser element capable of increasing the output.

  Another object of the present invention is to provide a surface emitting laser array including a surface emitting laser element capable of increasing output.

  Furthermore, another object of the present invention is to provide an optical scanning device including a surface emitting laser array composed of surface emitting laser elements capable of increasing output.

  Furthermore, another object of the present invention is to provide an electrophotographic apparatus using a surface emitting laser array provided with a surface emitting laser element capable of increasing output.

From a first viewpoint, the present invention comprises a semiconductor distributed Bragg reflector, a first reflective layer formed on a substrate, and a second reflective layer formed in contact with the first reflective layer; A resonator including an active layer formed in contact with the second reflective layer, a third reflective layer formed in contact with the resonator, and formed in contact with the third reflective layer A fourth reflective layer, wherein the resonator is made of an AlGaInPAs-based material, and the second reflective layer includes N (N is a positive integer) first high refractive index layers and N first reflective layers. The third reflective layer includes M (M is a positive integer) second high refractive index layers and M second layers. It includes a laminated body in which a low refractive index layer are alternately laminated, each of the N first low refractive index layer and said M second low refractive index layer, (Al _x a _1-x) consists _{0.5 In 0.5 P (0 ≦ x} ≦ 1), each of said N first high refractive index layer and the M second high refractive index layer, (Al _y Ga _1-y ) _0.5 In _0.5 P (0 ≦ y <x ≦ 1), and one of the N first low-refractive-index layers is one first low-refractive index. The refractive index layer is in contact with the resonator, and one of the N first high refractive index layers is in contact with the AlGaAs-based material constituting the first reflective layer. , One second low refractive index layer of the M second low refractive index layers is in contact with the resonator, and one of the M second high refractive index layers is The second high refractive index layer is a surface emitting laser element in contact with the AlGaAs material constituting the fourth reflective layer.

According to a second aspect of the present invention, a first reflective layer laminated on a substrate, a resonator made of an AlGaInPAs-based material, laminated on the first reflective layer, and laminated on the resonator A second reflective layer including a laminate in which n (n is a positive integer) number of pairs of high refractive index layers and low refractive index layers are laminated on the second reflective layer, A third reflective layer including a layer made of an AlGaAs-based material, wherein the low refractive index layer is made of (Al _x Ga _1-x ) _0.5 In _0.5 P (0 ≦ x ≦ 1) The high refractive index layer is made of (Al _y Ga _1-y ) _0.5 In _0.5 P (0 ≦ y <x ≦ 1), and the stacked body has the high refractive index layer as the third refractive index layer. This is a surface emitting laser element in contact with a layer made of an AlGaAs material of the reflective layer.

  From a third aspect, the present invention includes a plurality of surface-emitting laser elements each of which is a surface-emitting laser element of the present invention, and the plurality of surface-emitting laser elements are arranged at equal intervals. The surface emitting laser array is arranged at an intersection of a plurality of second base lines that are arranged at equal intervals with the first base line and each form a predetermined angle with the first base line.

  According to a fourth aspect of the present invention, there is provided the surface-emitting laser array of the present invention, a light-receiving unit that receives the laser light emitted from the surface-emitting laser array, and the light-receiving unit at a time other than during image recording. It is an optical scanning device provided with the moving means to move on the optical axis of the emitted laser beam.

  According to a fifth aspect of the present invention, the surface emitting laser array of the present invention, a light receiving means for receiving laser light emitted from the surface emitting laser array, and a part of the emitted laser light are received by the light receiving device. An optical scanning device comprising light guiding means for guiding to the means.

  From a sixth viewpoint, the present invention is an electrophotographic apparatus provided with the optical scanning device of the present invention.

In the surface emitting laser element according to the present invention, the low refractive index layer of the reflective layer formed in contact with the resonator is (Al _x Ga _1-x ) _0.5 In _0.5 P (0 ≦ x ≦ 1). The high refractive index layer of the reflective layer formed in contact with the resonator is made of (Al _y Ga _1-y ) _0.5 In _0.5 P (0 ≦ y <x ≦ 1). Is made of an AlGaInPAs-based material. As a result, carriers can be confined in the active layer, and the resistance of the reflective layer formed in contact with the resonator can be reduced.

  Therefore, according to the present invention, the output of the surface emitting laser element can be increased.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[First Embodiment]
FIG. 1 is a schematic sectional view of a surface emitting laser device according to a first embodiment of the present invention. Referring to FIG. 1, a surface emitting laser device 100 according to a first embodiment of the present invention includes a substrate 101, reflective layers 102, 103, 107, 108, spacer layers 104, 106, an active layer 105, A selective oxidation layer 109, a contact layer 110, an SiO ₂ layer 111, an insulating resin 112, a p-side electrode 113, and an n-side electrode 114 are provided. The surface emitting laser element 100 is a 780 nm band surface emitting laser element.

The substrate 101 is made of (100) n-type gallium arsenide (n-GaAs) whose plane orientation is inclined at an inclination angle of 15 degrees in the (111) A plane direction. When the pair of n-Al _0.95 Ga _0.05 As / n-Al _0.35 Ga _0.65 As is taken as one period, the reflective layer 102 has [n-Al _0.95 Ga of 35.5 periods. _0.05 As / n-Al _0.35 Ga _0.65 As] and formed on one main surface of the substrate 101. The film thickness of each of n-Al _0.95 Ga _0.05 As and nAl _0.35 Ga _0.65 As is λ / 4n (where n is the wavelength when the oscillation wavelength of the surface emitting laser element 100 is λ). The refractive index of the semiconductor layer).

The reflective layer 103 is made of an AlGaInP-based material and is formed in contact with the reflective layer 102. The spacer layer 104 is made of (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P and is formed in contact with the reflective layer 103. When the active layer 105 includes a pair of Ga _0.8 In _0.2 P _0.2 As _0.8 / (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P as one period, 3 It has a period of [Ga _0.8 In _0.2 P _0.2 As _0.8 / (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P], and is formed in contact with the spacer layer 104. The

The spacer layer 106 is made of (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P and is formed in contact with the active layer 105. The reflective layer 107 is made of an AlGaInP-based material and is formed in contact with the spacer layer 106.

When the pair of p-Al _0.95 Ga _0.05 As / p-Al _0.35 Ga _0.65 As is taken as one period, the reflective layer 108 has [n-Al _0.95 Ga of 29.5 periods. _0.05 As / n-Al _0.35 Ga _0.65 As], and is formed in contact with the reflective layer 107. The film thickness of each of p-Al _0.95 Ga _0.05 As and p-Al _0.35 Ga _0.65 As is λ / 4n (n is the refractive index of the semiconductor layer).

  The selective oxidation layer 109 is made of p-AlAs and is provided in the reflection layer 108. The selective oxidation layer 109 includes a non-oxidized region 109a and an oxidized region 109b and has a thickness of 20 nm.

The contact layer 110 is made of p-GaAs and is formed on the reflective layer 108. The SiO ₂ layer 111 covers one main surface of a part of the reflective layer 103 and the end surfaces of the spacer layer 104, the active layer 105, the spacer layer 106, the reflective layers 107 and 108, the selective oxidation layer 109, and the contact layer 110. Formed.

The insulating resin 112 is formed in contact with the SiO ₂ layer 111. The p-side electrode 113 is formed on part of the contact layer 110 and the insulating resin 112. The n-side electrode 114 is formed on the back surface of the base plate 101.

  Each of the reflective layers 102 and 103 and the reflective layers 107 and 108 constitutes a semiconductor distributed Bragg reflector that reflects the oscillation light oscillated in the active layer 105 by Bragg multiple reflection and confines it in the active layer 105.

  The oxidized region 109b has a smaller refractive index than the non-oxidized region 109a. The oxidized region 109b forms a current confinement portion that restricts the path through which the current injected from the p-side electrode 113 flows to the active layer 105 to the non-oxidized region 109a, and also oscillates the oscillation light oscillated in the active layer 105. Confine in the region 109a. Thus, the surface emitting laser element 100 can oscillate with a low threshold current.

FIG. 2 is a cross-sectional view of the four reflective layers 102, 103, 107, and 108, the two spacer layers 104 and 106, and the active layer 105 shown in FIG. Referring to FIG. 2, active layer 105 includes well layers 105A, 105C, and 105E and barrier layers 105B and 105D. Each of the well layers 105A, 105C, and 105E is made of Ga _0.8 In _0.2 P _0.2 As _0.8 , and each of the barrier layers 105B and 105D is (Al _0.1 Ga _0.9 ) _{0. .5} In _0.5 P. Thus, the active layer 105 is composed of three well layers and two barrier layers. The well layer 105A is in contact with the spacer layer 104, and the well layer 105E is in contact with the spacer layer 106.

The reflective layer 102 has a structure in which low refractive index layers 1021 and high refractive index layers 1022 are alternately stacked. The low refractive index layer 1021 is made of n-Al _0.95 Ga _0.05 As, and the high refractive index layer 1022 is made of n-Al _0.35 Ga _0.65 As. The lower refractive index layer 1021 disposed on the lowermost side is in contact with the substrate 101.

The reflective layer 103 includes a low refractive index layer 1031 and a high refractive index layer 1032. The low refractive index layer 1031 is made of n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and the high refractive index layer 1032 is n- (Al _0.1 Ga _0.9 ) _{0. .5} In _0.5 P. The high refractive index layer 1032 (= n- (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P) is the low refractive index layer 1021 (= n-Al _0.95 Ga) of the reflective layer 102. _0.05 As) and the low refractive index layer 1031 (= n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P) is formed on the spacer layer 104 (= (Al _{0. 1} Ga _0.9 ) _0.5 In _0.5 P).

The reflective layer 107 includes a low refractive index layer 1071 and a high refractive index layer 1072. The low refractive index layer 1071 is made of p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and the high refractive index layer 1072 is p- (Al _0.1 Ga _0.9 ) _{0. .5} In _0.5 P.

The reflective layer 108 has a structure in which low refractive index layers 1081 and high refractive index layers 1082 are alternately stacked. The low refractive index layer 1081 is made of p-Al _0.95 Ga _0.05 As, and the high refractive index layer 1082 is made of p-Al _0.35 Ga _0.65 As. The uppermost high refractive index layer 1082 is in contact with the contact layer 110.

The high refractive index layer 1072 (= p- (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P) in the reflective layer 107 is a low refractive index layer (= p-Al) of the reflective layer 108. _0.95 Ga _0.05 As), the low refractive index layer 1071 (= p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P) in the reflective layer 107 is The spacer layer 106 is formed in contact with (= Al _0.1 Ga _0.9 ) _0.5 In _0.5 P).

  In the surface-emitting laser element 100, the spacer layers 104 and 106 and the active layer 105 constitute a “resonator”, and the length of the resonator is set to one wavelength (= λ).

  FIG. 3 is an energy band diagram of a part of the two reflective layers 102 and 108 shown in FIG. 2, the two reflective layers 103 and 107, and the resonator (= the spacer layers 104 and 106 and the active layer 105).

FIG. 4 is a diagram showing the relationship between the composition ratio x of aluminum (Al) and the potential energy. In FIG. 4, the vertical axis represents potential energy, and the horizontal axis represents the Al composition ratio x. A curve k1 shows the relationship between the potential energy of Al _x Ga _1-x As (0 ≦ x ≦ 1) and the Al composition ratio x, and a curve k2 shows (Al _x Ga _1-x ) _0.5 In The relationship between the potential energy of _0.5 P (0 ≦ x ≦ 1) and the Al composition ratio x is shown.

Referring to FIG. 3, the low refractive index layer 1031 of the reflective layer 103 is made of n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and the low refractive index layer 1071 of the reflective layer 107. Is made of p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and each of the well layers 105A, 105C, and 105E of the active layer 105 has Ga _0.8 In _0.2 P _{0. .2} As _0.8 , and each of the barrier layers 105B and 105D is made of (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P. As a result, the potential energy of the conduction band of the resonator is about 0.22 eV, the potential energy of the conduction bands of the low refractive index layers 1031 and 1071 is about 0.38 eV, and the energy difference between them is 0. 16 eV.

The high refractive index layer 1032 made of n- (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P and p- (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P Each of the high refractive index layers 1072 made of has a valence band potential energy of about −1.75 eV (see curve k2 in FIG. 4), and is made of n-Al _0.95 Ga _0.05 As. Each of the refractive index layer 1021 and the low refractive index layer 1081 made of pAl _0.95 Ga _0.05 As has a valence band potential energy of about −1.84 eV (see curve k1 in FIG. 4). The energy difference between them is -0.09 eV.

FIG. 5 is an energy band diagram of a resonator and a reflective layer of a conventional surface emitting laser element. Referring to FIG. 5A, in the conventional surface emitting laser element 200, the resonator is made of Ga _0.5 In _0.5 P (generally, an AlGaInP-based material) and has a low refractive index. The layer a1 is made of Al _0.95 Ga _0.05 As (generally, an AlGaAs-based material). As a result, in the surface emitting laser element 200, the potential energy of the conduction band of the resonator is about 0.22 eV, the potential energy of the low refractive index layer a1 is about 0.30 eV, and the energy difference between the two is 0.08 eV.

5B, in the conventional surface emitting laser element 200A, the resonator is made of Ga _0.5 In _0.5 P (generally, an AlGaInP-based material), and has a low The refractive index layer b1 is made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P (generally, an AlGaInP-based material), and the high refractive index layer b2 is Al _0.35 Ga _{0. .65} As (generally an AlGaAs material). As a result, the potential energy of the valence band of the low refractive index layer b1 is about −1.94 eV, the potential energy of the valence band of the high refractive index layer b2 is about −1.57 eV, and the energy difference between the two is , −0.37 eV.

  Therefore, the surface emitting laser element 100 according to the present invention can make the energy difference of the conduction band at the interface between the resonator and the reflecting layers 103 and 107 larger than that of the conventional surface emitting laser element 200. Further, the energy difference between the low refractive index layer 1031 and the high refractive index layer 1032 can be made smaller than that of the conventional surface emitting laser element 200A. As a result, in the surface emitting laser element 100, carriers can be confined in the active layer 105 as compared with the conventional surface emitting laser element, and the resistances of the reflective layers 103 and 107 can be greatly reduced, thereby obtaining a high output. it can.

The high refractive index layer 1032 of the reflective layer 103 is made of n- (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P, and the low refractive index layer 1021 of the reflective layer 102 is n-Al. _{Since it is made of 0.95} Ga _0.05 As, a P-type material / As-type material bonding interface 1023 is formed at the interface between the high refractive index layer 1032 of the reflective layer 103 and the low refractive index layer 1021 of the reflective layer 102. .

Further, the high refractive index layer 1072 of the reflective layer 107 is made of p- (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P, and the low refractive index layer 1081 of the reflective layer 108 is p-Al. _{Since it is made of 0.95} Ga _0.05 As, a P-type material / As-type material bonding interface 1083 is formed at the interface between the high refractive index layer 1072 of the reflective layer 107 and the low refractive index layer 1081 of the reflective layer 108. (See FIG. 3).

  On the other hand, in the conventional surface emitting laser element 200, the P-type material / As-based material junction interface exists at the interface between the resonator and the low refractive index layer a1, and in the conventional surface emitting laser element 200A, P The bonding interface of the system material / As system material exists at the interface between the low refractive index layer b1 and the high refractive index layer b2.

  Therefore, in the surface emitting laser element 100, the P-system / As-based material bonding interfaces 1023 and 1083 are formed at positions farther from the active layer than the conventional surface emitting laser elements 200 and 200A. As a result, the lifetime of the surface emitting laser element 100 can be extended.

  Note that the number of pairs of the [low refractive index layer 1031 / high refractive index layer 1032] of the reflective layer 103 and the number of pairs of [low refractive index layer 1071 / high refractive index layer 1072] of the reflective layer 107 are not limited to one. The number of sets may be two or more.

FIG. 6 is a diagram showing the relationship between the thermal conductivity and the Al composition ratio x. In FIG. 6, the vertical axis represents the thermal conductivity, and the horizontal axis represents the Al composition ratio x. Curve k3 shows the relationship between the thermal conductivity of Al _x Ga _1-x As (0 ≦ x ≦ 1) and the Al composition ratio x, and curve k4 shows (Al _x Ga _1-x ) _0.5. The relationship between the thermal conductivity of In _0.5 P (0 ≦ x ≦ 1) and the Al composition ratio x is shown.

When the (Al _x Ga _1-x ) _0.5 In _0.5 P (0 ≦ x ≦ 1) material is used for the reflective layers 103 and 107, the thermal conductivity of the reflective layers 103 and 107 is as follows. Since it becomes lower than the case where Al _x Ga _1-x As (0 ≦ x ≦ 1) type material is used for 103 and 107 (see curves k3 and k4), the [low refractive index layer 1031 / high refraction of the reflective layer 103] The number of sets of the index layer 1032] and the number of sets of the [low refractive index layer 1071 / high refractive index layer 1072] of the reflective layer 107 are set to as few as possible in consideration of heat dissipation characteristics.

  7, 8, and 9 are first to third process diagrams showing a method for manufacturing the surface-emitting laser element 100 shown in FIG. 1, respectively. Referring to FIG. 7, when a series of operations is started, reflection layers 102 and 103, spacer layer 104, active layer 105, spacers are formed using metal organic chemical vapor deposition (MOCVD). The layer 106, the reflective layers 107 and 108, the selective oxidation layer 109, and the contact layer 110 are sequentially stacked on the substrate 101 (see step (a) in FIG. 7).

In this case, n-Al _0.95 Ga _0.05 As and n-Al _0.5 Ga _0.65 As of the reflective layer 102 are changed to trimethylaluminum (TMA), trimethylgallium (TMG), arsine (AsH ₃ ), and selenium. Formed using hydrogen halide (H ₂ Se) as a raw material, n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P and n- (Al _0.1 Ga _0.9 ) of the reflective layer 103 _0.5 In _0.5 P is formed using trimethylaluminum (TMA), trimethylgallium (TMG), trimethylindium (TMI), phosphine (PH ₃ ), and hydrogen selenide (H ₂ Se) as raw materials.

Further, (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P of the spacer layer 104 is made from trimethylaluminum (TMA), trimethylgallium (TMG), trimethylindium (TMI), and phosphine (PH ₃ ) as raw materials. Form as.

Further, forming a _{Ga 0.8 In} 0.2 _P 0.2 _As 0.8 of the active layer 105 trimethyl gallium (TMG), trimethylindium (TMI), phosphine (PH ₃₎ and arsine (AsH ₃₎ as a raw material And (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P of the active layer 105 with trimethylaluminum (TMA), trimethylgallium (TMG), trimethylindium (TMI), and phosphine (PH ₃ ). Form as a raw material.

Further, (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P of the spacer layer 106 is replaced with trimethylaluminum (TMA), trimethylgallium (TMG), trimethylindium (TMI), and phosphine (PH ₃ ). Form as a raw material.

Further, p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P and p (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P of the reflective layer 107 are changed to trimethylaluminum ( TMA), trimethylgallium (TMG), trimethylindium (TMI), phosphine (PH ₃ ) and carbon tetrabromide (CBr ₄ ) are used as raw materials. Note that dimethyl zinc (DMZn) may be used instead of carbon tetrabromide (CBr ₄ ).

Further, p-Al _0.95 Ga _0.05 As and p-Al _0.35 Ga _0.65 As of the reflective layer 108 are changed to trimethylaluminum (TMA), trimethylgallium (TMG), arsine (AsH ₃ ), and four odors. Carbonized carbon (CBr ₄ ) is used as a raw material. Also in this case, dimethyl zinc (DMZn) may be used instead of carbon tetrabromide (CBr ₄ ).

Further, p-AlAs of the selective oxidation layer 109 is formed using trimethylaluminum (TMA), arsine (AsH ₃ ), and carbon tetrabromide (CBr ₄ ) as raw materials, and p-GaAs of the contact layer 110 is formed of trimethylgallium (TMG). , Arsine (AsH ₃ ) and carbon tetrabromide (CBr ₄ ). Also in this case, dimethyl zinc (DMZn) may be used instead of carbon tetrabromide (CBr ₄ ).

  Thereafter, a resist is applied on the contact layer 110, and a resist pattern 120 is formed on the contact layer 110 using a photoengraving technique (see step (b) in FIG. 7).

  When the resist pattern 120 is formed, a part of the reflective layer 103, the spacer layer 104, the active layer 105, the spacer layer 106, the reflective layers 107 and 108, the selective oxidation layer 109, and the contact are formed using the formed resist pattern 120 as a mask. The peripheral portion of the layer 110 is removed by dry etching, and the resist pattern 120 is further removed (see step (c) in FIG. 7).

In dry etching, a halogen-based gas such as Cl ₂ , BCl ₃ , or SiCl ₄ is introduced, and a reactive ion beam etching method (RIBE) or an inductively coupled plasma etching method (ICP: Inductively Coupled Plasma Plasma) is used. ) Method and reactive ion etching (RIE: Reactive Ion Etching) method.

  In the regions of the reflective layers 103 and 107, the spacer layers 104 and 106, and the active layer 105 of the surface emitting laser element 100, an AlGaInPAs-based material is used. In dry etching of a material containing In, since the vapor pressure of chloride of In is low, the etching rate can be reduced with respect to the semiconductor distributed Bragg reflector (reflective layers 102 and 108) made of an AlGaAs material. That is, since the resonator region including the spacer layers 104 and 106 and the active layer 105 can be used as a layer for stopping etching depending on the etching conditions, it is possible to absorb lot-to-lot variations and in-plane distribution of the etching rate, and selectively oxidize. The layer 109 can be etched and the etching depth can be prevented from reaching the reflective layer 102. For these reasons, a part of the reflective layer 103, the spacer layer 104, the active layer 105, the spacer layer 106, the reflective layers 107 and 108, the selective oxidation layer 109, and the peripheral portion of the contact layer 110 using a halogen-based gas. Is dry-etched.

  Next, referring to FIG. 8, after step (c) shown in FIG. 7, the sample is heated to 425 ° C. in an atmosphere in which water heated to 85 ° C. is bubbled with nitrogen gas, thereby selectively oxidizing layer 109. Is oxidized from the outer peripheral portion toward the central portion to form a non-oxidized region 109a and an oxidized region 109b in the selective oxide layer 109 (see step (d) in FIG. 8).

Thereafter, a SiO ₂ layer 111 is formed on the entire surface of the sample by using a chemical vapor deposition (CVD) method, and a region serving as a light emitting portion and a surrounding SiO ₂ layer using a photoengraving technique. 111 is removed (see step (e) in FIG. 8).

  Next, the insulating resin 112 is applied to the entire sample by spin coating, and the insulating resin 112 on the region to be the light emitting portion is removed (see step (f) in FIG. 8).

  Referring to FIG. 9, after forming insulating resin 112, a resist pattern having a predetermined size is formed on a region to be a light emitting portion, and a p-side electrode material is formed on the entire surface of the sample by vapor deposition. The p-side electrode 113 is formed by removing the p-side electrode material on the pattern by lift-off (see step (g) in FIG. 9). Then, the back surface of the substrate 101 is polished, the n-side electrode 114 is formed on the back surface of the substrate 101, and further annealed to establish ohmic conduction between the p-side electrode 113 and the n-side electrode 114 (step (h) in FIG. 9). reference). Thus, the surface emitting laser element 100 is manufactured.

  In the surface emitting laser element 100, as described above, the energy difference of the conduction band at the interface between the resonator and the reflecting layers 103 and 107 can be made larger than that of the conventional surface emitting laser element, and the value in the reflecting layers 103 and 107 can be increased. The energy difference of the electron band can be made smaller than that of the conventional surface emitting laser element. As a result, in the surface emitting laser element 100, carriers can be confined in the active layer 105 as compared with the conventional surface emitting laser element, and the resistances of the reflective layers 103 and 107 can be greatly reduced, thereby obtaining a high output. it can.

In the above description, it has been described that the low refractive index layer 1031 of the reflective layer 103 and the low refractive index layer 1071 of the reflective layer 107 are made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P. In the invention, the present invention is not limited to this, and the low refractive index layers 1031 and 1071 are generally made of (Al _x Ga _1-x ) _0.5 In _0.5 P (0 ≦ x ≦ 1). Just do it.

In the above description, the high refractive index layer 1032 of the reflective layer 103 and the high refractive index layer 1072 of the reflective layer 107 are described as being made of (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P. In the present invention, not limited to this, the high refractive index layers 1032 and 1072 are generally (Al _y Ga _1-y ) _0.5 In _0.5 P (0 ≦ y <x ≦ 1). It should just be comprised from.

[Second Embodiment]
FIG. 10 is a schematic cross-sectional view of a surface emitting laser element according to the second embodiment. Referring to FIG. 10, the surface emitting laser element 100A according to the second embodiment is obtained by replacing the reflecting layers 103 and 107 of the surface emitting laser element 100 shown in FIG. 1 with reflecting layers 103A and 107A, respectively. Is the same as that of the surface emitting laser element 100.

  FIG. 11 is a cross-sectional view of the two reflective layers 102 and 103A shown in FIG. Referring to FIG. 11, the reflective layer 103 </ b> A is obtained by adding an intermediate layer 1033 to the reflective layer 103 shown in FIG. 2, and is otherwise the same as the reflective layer 103.

The intermediate layer 1033 is made of n- (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P, and is formed between the low refractive index layer 1031 and the high refractive index layer 1032.

  FIG. 12 is another cross-sectional view of the two reflective layers 107A and 108 shown in FIG. Referring to FIG. 12, reflective layer 107A is obtained by adding intermediate layer 1073 to reflective layer 107 shown in FIG.

The intermediate layer 1073 is made of p- (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P, and is formed between the low refractive index layer 1071 and the high refractive index layer 1072.

  FIG. 13 is an energy band diagram of a part of the two reflective layers 102 and 108 shown in FIG. 10, two reflective layers 103A and 107A, and a resonator (= spacer layers 104 and 106 and active layer 105).

  Referring to FIG. 13, intermediate layer 1033 has a band gap between the band gap of high refractive index layer 1032 and the band gap of low refractive index layer 1031. The intermediate layer 1073 has a band gap between the band gap of the high refractive index layer 1072 and the band gap of the low refractive index layer 1071.

  When the difference between the Al composition ratio of the low-refractive index layer 1031 and the Al composition ratio of the high-refractive index layer 1032 is large, the band discontinuity of the valence band in the reflective layer 103 becomes large, so the Al composition of the low-refractive index layer 1031 Is inserted between the low refractive index layer 1031 and the high refractive index layer 1032 to insert a valence electron in the reflective layer 103A. The band discontinuity of the band is reduced, and the resistance of the reflective layer 103A can be reduced.

  Further, when the difference between the Al composition ratio of the low refractive index layer 1071 and the Al composition ratio of the high refractive index layer 1072 is large, the band discontinuity of the valence band in the reflective layer 107 becomes large. By inserting an intermediate layer 1073 having an Al composition ratio intermediate between the Al composition ratio and the Al composition ratio of the high refractive index layer 1072 between the low refractive index layer 1071 and the high refractive index layer 1072, Band discontinuity in the valence band is reduced, and the resistance of the reflective layer 107A can be reduced.

  Therefore, by providing the intermediate layers 1033 and 1073 in the reflective layers 103A and 107A, respectively, the resistance of the reflective layers 103A and 107A can be reduced and the output of the surface emitting laser element 100A can be increased.

  The surface emitting laser element 100A is manufactured according to the steps (a) to (h) shown in FIGS. In this case, in the step (a), the reflective layers 103A and 107A are laminated instead of the reflective layers 103 and 107, respectively.

In the above, the intermediate layer 1033 _is made of _{n- (Al 0.4 Ga 0.6) 0.5} In 0.5 P, the intermediate layer _{1073, p- (Al} 0.4 _{Ga 0.6} ) _0.5 In _0.5 P has been described, but in the present invention, the present invention is not limited to this, and the intermediate layer 1033 has n- (Al _z Ga _1-z ) _0.5 In _0.5 P (0 ≦ z ≦ 1, y <z <x), and the intermediate layer 1073 has p- (Al _z Ga _1−z ) _0.5 In _0.5 P (0 ≦ z ≦ 1, y <z <x). It only has to consist of.

Further, the intermediate layer 1033 includes a plurality of n- (Al _z Ga _1-z ) _0.5 In ₀ ... N n (Al _z Ga _{1 -z} ) _0.5 band bands whose band gap decreases continuously or stepwise from the low refractive index layer 1031 to the high refractive index layer 1032 _{. 5} may be composed of P, the intermediate layer 1073, a low refractive index layer 1071 bandgap towards the high-refractive index layer 1072 is continuously or stepwise reduced more _p- (Al z _{Ga 1- z} ) It may be composed of _0.5 In _0.5 P.

  Others are the same as the first embodiment.

[Third Embodiment]
FIG. 14 is a schematic cross-sectional view of a surface emitting laser element according to the third embodiment. Referring to FIG. 14, the surface emitting laser element 100B according to the third embodiment is obtained by replacing the reflecting layers 103 and 107 of the surface emitting laser element 100 shown in FIG. 1 with reflecting layers 103B and 107B, respectively. Is the same as that of the surface emitting laser element 100.

  FIG. 15 is a cross-sectional view of the two reflective layers 102 and 103B shown in FIG. Referring to FIG. 15, a reflective layer 103B is obtained by adding an intermediate layer 1034 to the reflective layer 103A shown in FIG. 11, and is otherwise the same as the reflective layer 103A.

The intermediate layer 1034 is made of n- (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P, and is formed between the low refractive index layer 1031 and the resonator.

  FIG. 16 is another cross-sectional view of the two reflective layers 107B and 108 shown in FIG. Referring to FIG. 16, a reflective layer 107B is obtained by adding an intermediate layer 1074 to the reflective layer 107A shown in FIG. 12, and the rest is the same as the reflective layer 107A.

The intermediate layer 1074 is made of p- (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P, and is formed between the low refractive index layer 1071 and the resonator.

  FIG. 17 is an energy band diagram of a part of the two reflective layers 102 and 108 shown in FIG. 14, the two reflective layers 103B and 107B, and the resonator (= the spacer layers 104 and 106 and the active layer 105).

  Referring to FIG. 17, the intermediate layer 1034 has a band gap between the band gap of the spacer layer 104 constituting the resonator and the band gap of the low refractive index layer 1031. Further, the intermediate layer 1074 has a band gap between the band gap of the spacer layer 106 constituting the resonator and the band gap of the low refractive index layer 1071.

  When the difference between the Al composition ratio of the spacer layer 104 and the Al composition ratio of the low refractive index layer 1031 is large, the band discontinuity of the valence band in the reflective layer 103A becomes large. By inserting an intermediate layer 1034 having an Al composition ratio intermediate to the Al composition ratio of the refractive index layer 1031 between the spacer layer 104 and the low refractive index layer 1031, band discontinuity of the valence band in the reflective layer 103 </ b> B is reduced. As a result, the resistance of the reflective layer 103B can be reduced.

  In addition, when the difference between the Al composition ratio of the spacer layer 106 and the Al composition ratio of the low refractive index layer 1071 is large, the band discontinuity of the valence band in the reflective layer 107A becomes large, so the Al composition of the low refractive index layer 1071 Is inserted between the spacer layer 106 and the low refractive index layer 1071, so that the valence band in the reflective layer 107B can be reduced. Band discontinuity is reduced, and the resistance of the reflective layer 107B can be reduced.

  Therefore, by providing the intermediate layers 1034 and 1074 in the reflective layers 103B and 107B, respectively, the resistance of the reflective layers 103B and 107B can be reduced and the output of the surface emitting laser element 100B can be increased.

  The surface emitting laser element 100B is manufactured according to the steps (a) to (h) shown in FIGS. In this case, in the step (a), the reflective layers 103B and 107B are laminated in place of the reflective layers 103 and 107, respectively.

In the above, the intermediate layer 1034 is made of n- (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P, and the intermediate layer 1074 is p- (Al _0.4 Ga _0.6. ) _0.5 has been described with in consist _0.5 P, the present invention is not limited thereto, the intermediate layer _{1034, n- (Al z Ga 1-} z) 0.5 in 0.5 P (0 ≦ z ≦ 1, y <z <x), and the intermediate layer 1074 has p- (Al _z Ga _1−z ) _0.5 In _0.5 P (0 ≦ z ≦ 1, y <z <x). It only has to consist of.

Further, the intermediate layer 1034 includes a plurality of n- (Al _z Ga _1-z ) _0.5 In _0.5 Ps in which the band gap decreases continuously or stepwise from the low refractive index layer 1031 toward the spacer layer 104. The intermediate layer 1074 may be formed of a plurality of p- (Al _z Ga _1-z ) ₀ ... Band bands whose band gap decreases continuously or stepwise from the low refractive index layer 1071 to the spacer layer 106 _{. It} may be composed of ₅ In _0.5 P.

  Others are the same as the first embodiment.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. As shown in FIG. 18, the surface emitting laser element 100 </ b> C according to the fourth embodiment is obtained by replacing the reflective layer 102 of the surface emitting laser element 100 with a reflective layer 102 </ b> A. Is the same.

The reflective layer 102A has 35.5 pairs of a low refractive index layer 1021a made of n-AlAs and a high refractive index layer 1022 made of n-Al _0.35 Ga _0.65 As as a pair. That is, the low refractive index layer 1021 in the reflective layer 102 of the surface emitting laser element 100 is replaced with the low refractive index layer 1021a.

  In the fourth embodiment, since the AlAs layer having a lower thermal resistance than the AlGaAs material is used for the low refractive index layer 1021a of the reflective layer 102A, the heat generated in the active layer is more effectively transferred to the substrate side. Can be released. Therefore, the temperature rise of the active layer can be suppressed, and the VCSEL characteristics such as an increase in light output can be improved.

  By the way, considering only thermal characteristics, it is more desirable that the high refractive index layer is also GaAs. However, when the emission wavelength in the active layer is 850 nm or less, it cannot be used because there is absorption in the GaAs layer. .

  In the fourth embodiment, the case where the optical thickness of all the low refractive index layers 1021a in the reflective layer 102A is λ / 4 has been described. However, the present invention is not limited to this. For example, FIG. In the reflective layer 102A, the optical thickness of the low refractive index layer 1021a in contact with the reflective layer 103 may be 3λ / 4. Thereby, the heat generated in the active layer 105 can be released to the substrate side more efficiently.

  In this case, the optical thickness of the low refractive index layer 1021a in contact with the reflective layer 103 may be 5λ / 4 or 7λ / 4. In short, the optical thickness of the low refractive index layer 1021a in contact with the reflective layer 103 may be λ / 4 or more.

  In this case, the optical thickness of not only the low refractive index layer 1021a in contact with the reflective layer 103 but also a plurality of low refractive index layers 1021a close to the reflective layer 103 may be λ / 4 or more.

  Further, in the reflective layer 103, when there is a large difference in Al composition between the refractive index layers, the low refractive index layer 1031 and the high refractive index layer 1032 are interposed between the low refractive index layer 1031 and the high refractive index layer 1032 as in the surface emitting laser element 100A described above. An intermediate layer 1033 may be inserted (see FIG. 20). Thereby, the discontinuity of a band becomes small and element resistance can be reduced. Note that the intermediate layer may be formed of a plurality of semiconductor layers so that the band gap gradually changes stepwise in the intermediate layer.

  Further, in the reflective layer 107, when the difference in Al composition between the refractive index layers is large, the low refractive index layer 1071 and the high refractive index layer 1072 are interposed between the low refractive index layer 1071 and the surface emitting laser element 100A described above. An intermediate layer 1073 may be inserted (see FIG. 20). Thereby, the discontinuity of a band becomes small and element resistance can be reduced. Note that the intermediate layer may be formed of a plurality of semiconductor layers so that the band gap gradually changes stepwise in the intermediate layer.

  Further, in the reflective layer 103, when the difference in Al composition between the low refractive index layer 1031 and the spacer layer 104 is large, between the low refractive index layer 1031 and the spacer layer 104, similar to the surface emitting laser element 100B described above. Further, the intermediate layer 1034 as a bonding layer may be inserted (see FIG. 20). Thereby, the discontinuity of a band becomes small and element resistance can be reduced. Note that the intermediate layer may be formed of a plurality of semiconductor layers so that the band gap gradually changes stepwise in the intermediate layer.

  Further, in the reflective layer 107, when the difference in Al composition between the refractive index layers of the low refractive index layer 1071 and the spacer layer 106 is large, the low refractive index layer 1071 and the spacer are separated as in the surface emitting laser element 100B described above. The intermediate layer 1074 as a bonding layer may be inserted between the layer 106 (see FIG. 20). Thereby, the discontinuity of a band becomes small and element resistance can be reduced. Note that the intermediate layer may be formed of a plurality of semiconductor layers so that the band gap gradually changes stepwise in the intermediate layer.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. A surface emitting laser element 100D according to the fifth embodiment is obtained by replacing the reflective layer 103 of the surface emitting laser element 100 with a reflective layer 103C as shown in FIG. Is the same.

The reflective layer 103C includes a low-refractive index layer 1031a made of an AlGaAs-based material (for example, the same as the low-refractive index layer 1021, n-Al _0.95 Ga _0.05 As) and a high-refractive index layer 1032a (for example, the high refractive index layer 1032 N-Al _0.35 Ga _0.65 As), which is the same as the refractive index layer 1022. Note that when the low refractive index layer 1031a is n-Al _0.95 Ga _0.05 As and the high refractive index layer 1032a is n-Al _0.35 Ga _0.65 As, the reflection layer 102C and the reflection layer 103C Since the reflection layer is composed of the same low refractive index layer and the same high refractive index layer, it can be regarded as one reflection layer.

  As a result, the reflective layer between the substrate 101 and the resonator is composed of only an AlGaAs material. As shown in FIG. 6, the AlGaAs-based material has a smaller thermal resistance than the AlGaInP-based material having any composition, and therefore, the heat generated in the active layer can be effectively released to the substrate side.

  In the reflective layer 107, when the difference in Al composition between the refractive index layers is large, the low refractive index layer 1071 and the high refractive index layer 1072 are disposed between the low refractive index layer 1071 and the surface emitting laser element 100A described above. An intermediate layer 1073 may be inserted (see FIG. 22). Thereby, the discontinuity of a band becomes small and element resistance can be reduced. Note that the intermediate layer may be formed of a plurality of semiconductor layers so that the band gap gradually changes stepwise in the intermediate layer.

  Further, in the reflective layer 107, when the difference in Al composition between the refractive index layers of the low refractive index layer 1071 and the spacer layer 106 is large, the low refractive index layer 1071 and the spacer are separated as in the surface emitting laser element 100B described above. The intermediate layer 1074 as a bonding layer may be inserted between the layer 106 (see FIG. 23). Thereby, the discontinuity of a band becomes small and element resistance can be reduced. Note that the intermediate layer may be formed of a plurality of semiconductor layers so that the band gap gradually changes stepwise in the intermediate layer.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. As shown in FIG. 24, the surface-emitting laser element 100E according to the sixth embodiment is obtained by replacing the reflective layer 103 of the surface-emitting laser element 100C with a reflective layer 103D, and the others are the surface-emitting laser elements 100C. Is the same.

The reflective layer 103D includes a low refractive index layer 1031b made of n-AlAs and a high refractive index layer 1032b made of n-Al _0.35 Ga _0.65 As. That is, the low refractive index layer 1031b is the same as the low refractive index layer 1021a of the reflective layer 102A, and the high refractive index layer 1032b is the same as the high refractive index layer 1022 of the reflective layer 102A. Therefore, since the reflective layer composed of the reflective layer 102A and the reflective layer 103D is composed of the same low refractive index layer and the same high refractive index layer, it can be regarded as one reflective layer.

  In the sixth embodiment, AlAs having a lower thermal resistance than the AlGaAs-based material is used for the low refractive index layer 1031b of the reflective layer 103D, so that heat generated in the active layer is more effectively released to the substrate side. can do. Therefore, the temperature rise of the active layer can be suppressed, and the VCSEL characteristics such as an increase in light output can be improved.

  By the way, considering only thermal characteristics, it is more desirable that the high refractive index layer is also GaAs. However, when the emission wavelength in the active layer is 850 nm or less, it cannot be used because there is absorption in the GaAs layer. .

  In the sixth embodiment, the case where the optical thickness of the low refractive index layer 1031b in contact with the resonator is λ / 4 in the reflective layer 103D has been described. However, the present invention is not limited to this. For example, As shown in FIGS. 25 and 26, the optical thickness of the low refractive index layer 1031b in contact with the resonator may be 3λ / 4. Thereby, the heat generated in the active layer can be released to the substrate side more efficiently.

  In this case, the optical thickness of the low refractive index layer 1031b in contact with the resonator may be 5λ / 4 or 7λ / 4. In short, the optical thickness of the low refractive index layer 1031b in contact with the resonator may be λ / 4 or more.

  In this case, not only the low refractive index layer 1031a in contact with the resonator but also the optical thickness of the plurality of low refractive index layers 1021a close to the resonator in the reflective layer 102A may be λ / 4 or more (see FIG. 27). ).

In the configuration shown in FIG. 27, the potential energy of the conduction band of the resonator is about 0.22 eV, the potential energy of the conduction band of the low refractive index layer 1071 is about 0.38 eV, and the energy difference between them is 0.16 eV. Carrier confinement can be greatly improved. If the low refractive index layer 1071 is p-Al _0.95 Ga _0.05 As and the high refractive index layer 1072 is p-Al _0.35 Ga _0.65 As, the conduction band of the resonator The potential energy is about 0.22 eV, the potential energy of the conduction band of the low refractive index layer 1071 is about 0.30 eV, and the energy difference between the two is 0.08 eV.

In the configuration shown in FIG. 27, the potential energy of the valence band of the high refractive index layer 1072 is about −1.75 eV, and the potential energy of the valence band of the low refractive index layer 1071 is about −1.84 eV. The energy difference between the two becomes −0.09 eV, and the element resistance can be greatly reduced. If the low refractive index layer 1071 is p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P and the high refractive index layer 1072 is p-Al _0.35 Ga _0.65 As. The potential energy of the valence band of the low refractive index layer 1071 is about -1.94 eV, the potential energy of the valence band of the high refractive index layer 1072 is about −1.57 eV, and the energy difference between the two is −0. 37 eV.

  As described above, in the sixth embodiment, it is possible to expect characteristics that are higher than those of the conventional ones for improving carrier confinement, reducing element resistance, and improving heat dissipation characteristics.

[Application example]
FIG. 28 is a plan view of a surface emitting laser array using the surface emitting laser element 100 shown in FIG. Referring to FIG. 28, the surface emitting laser array 300 includes 24 surface emitting laser elements 301 to 324.

  Each of the 24 surface emitting laser elements 301 to 324 includes the surface emitting laser element 100 shown in FIG. 1 and is arranged two-dimensionally. Three surface emitting laser elements 301, 309, 317; 302, 310, 318; 303, 311, 319; 304, 312, 320; 305, 313, 321; 306, 314, 322; 307, 315, 323; , 316, 324 are arranged at equal intervals along the first baseline.

  Also, the eight surface emitting laser elements 301 to 308; 309 to 316; 317 to 324 are arranged at equal intervals along the second base line. In this case, the interval between two adjacent surface emitting laser elements is set to d.

  The first baseline forms a predetermined angle with the second baseline. Accordingly, the eight projection points when the center points of the eight surface emitting laser elements 301 to 308; 309 to 316; 317 to 324 are projected onto the first baseline are equally spaced, and the spacing is h. It is.

  Since the surface-emitting laser element 100 is a surface-emitting type, it can be easily arrayed and the position accuracy of the element is high. Further, as described above, the surface emitting laser element 100 has a structure in which heat generation is suppressed by reducing the resistance of the reflective layers 103 and 107. Therefore, the surface emitting laser array 300 can be densified by reducing the interval between elements as compared with the conventional surface emitting laser array. As a result, the number of chips can be increased and the cost can be reduced.

  In addition, by integrating a large number of surface emitting laser elements 100 capable of high output operation on the same substrate, when applied to a writing optical system, simultaneously writing with a multi-beam becomes easy, and the writing speed is greatly improved, Even if the writing dot density increases, printing can be performed without reducing the printing speed. When the writing dot density is the same, the printing speed can be increased.

  That is, normally, in one main scan, after all the surface emitting laser elements 301 to 324 are turned on in correspondence with image data, sub-scanning is performed, and these steps are repeated to perform image recording. . That is, when the total number of surface emitting laser elements included in the surface emitting laser array 300 is n, image recording of n rows is performed by one main scanning, and compared with a case where one laser light source having the same output is used. Thus, image recording can be performed in a time of 1 / n.

  In the surface emitting laser array 300, each of the surface emitting laser elements 301 to 324 may be configured by any of the surface emitting laser elements 100A to 100E.

  FIG. 29 is a schematic diagram of an optical scanning device. Referring to FIG. 29, the optical scanning device 400 includes a surface emitting laser array 401, a collimator lens 402, a polygon mirror 403, and an fθ lens 304.

  The surface emitting laser array 401 includes the surface emitting laser array 300 shown in FIG. 28 and emits a plurality of beams. The collimator lens 402 guides the plurality of beams emitted from the surface emitting laser array 401 to the polygon mirror 403 as parallel light.

  The polygon mirror 403 rotates clockwise at a predetermined speed, and scans a plurality of beams received from the collimator lens 402 in the main scanning direction and the sub-scanning direction. Guide to lens 404. The fθ lens 404 guides the plurality of beams scanned by the polygon mirror 403 to the photoconductor 405. In this case, the fθ lens 404 guides the plurality of beams to the photoconductor 405 so that all of the plurality of beams scanned by the polygon mirror 403 are focused on the photoconductor 405.

  As described above, the optical scanning device 400 uses the same optical system including the collimator lens 402 and the polygon mirror 403 for a plurality of beams from the surface emitting laser array 401, rotates the polygon mirror 403 at high speed, and lights the dot position. And the light is condensed on the photoconductor 405 that is the surface to be scanned as a plurality of light spots separated in the sub-scanning direction.

  When an image is written using the optical scanning device 400, each surface emitting laser element 301 to 324 on the photosensitive band 405 is taken into account by taking into account each offset amount of each surface emitting laser element 301 to 324 with respect to the first baseline. Can be arranged in a straight line.

  Further, in an optical writing system having an equivalent optical output and an equivalent polygon mirror rotation speed, when the number of laser beams is n, the writing time required to rotate the photosensitive member 405 once is one. / N, which is significantly faster than the prior art.

  FIG. 30 is another schematic diagram of the optical scanning device. Referring to FIG. 30, optical scanning device 400A is the same as optical scanning device 400 except that light receiving element 406 and moving means 407 are added to optical scanning device 400 shown in FIG.

  The light receiving element 406 is moved by the moving means 407 between a position “a” outside the optical path of the laser beam and a position “b” on the optical axis of the laser beam. When the light receiving element 406 moves to the position b on the optical axis of the laser light, the light receiving element 406 detects the laser light emitted from the surface emitting laser array 401 and measures its output.

  The moving means 407 moves the light receiving element 406 to a position a outside the optical path of the laser beam when the optical scanning device 400A is writing an image, and receives light when the optical scanning device 400A is not writing an image. The element 406 is moved to the position b of the optical axis of the laser beam.

  In general, it has been confirmed that the output of a semiconductor laser gradually decreases with energization from a long-term viewpoint. This phenomenon is more or less applicable to all semiconductor lasers. The fluctuation of the laser output appears as uneven electric potential on the photosensitive member 405 in the latent image formation, and is finally observed as uneven image density. Therefore, when an image having a uniform density is formed, the laser light output must be made uniform.

  Therefore, when the optical scanning device 400A is not recording an image, the output of a plurality of laser beams emitted from the surface emitting laser array 401 can be measured by moving the light receiving element 406 onto the optical axis of the laser beam, Based on the measurement, by controlling the injection current to the plurality of surface emitting laser elements of the surface emitting laser array 401 so as to keep the outputs of the plurality of laser beams substantially uniform, an image having a uniform density can be obtained. 405 can be formed.

  Others are the same as the description in FIG.

  FIG. 31 is still another schematic diagram of the optical scanning device. Referring to FIG. 31, an optical scanning device 400B is the same as optical scanning device 400 except that half mirror 408 and light receiving element 409 are added to optical scanning device 400 shown in FIG.

  The half mirror 408 is disposed on the optical path between the collimator lens 402 and the polygon mirror 403. The half mirror 408 transmits part of the laser light from the collimator lens 402 to the polygon mirror 403 and reflects part of the laser light toward the light receiving element 409. The light receiving element 409 receives light from the half mirror 408.

  A part of the laser beam is reflected by the half mirror 408, and the reflected light is detected by the light receiving element 409, thereby outputting a plurality of laser beams emitted from the surface emitting laser array 401 without providing any moving means. By controlling the injection current to the plurality of surface emitting laser elements of the surface emitting laser array 401 so as to keep the output of the plurality of laser beams substantially uniform based on the measurement, a uniform concentration can be obtained. An image can be formed on the photoreceptor 405. Others are the same as the description in FIG.

  FIG. 32 is still another schematic diagram of the optical scanning device. Referring to FIG. 32, optical scanning device 400C is the same as optical scanning device 400B except that magnification lens 410 is added to optical scanning device 400B shown in FIG.

  The magnifying lens 410 is disposed between the half mirror 408 and the light receiving element 409. The magnifying lens 410 magnifies the plurality of laser beams from the half mirror 408 at a predetermined magnification, and guides the magnified laser beams to the light receiving element 409.

  Since the intervals between the plurality of laser beams emitted from the surface emitting laser array 401 are narrow, it is difficult to detect them separately.

  Therefore, the output of the plurality of laser beams can be accurately measured by enlarging the beam pitch of the plurality of laser beams by the magnifying lens 410 and guiding it to the light receiving element 409. As a result, it is possible to accurately control the injection current to the plurality of surface emitting laser elements of the surface emitting laser array 401 so as to keep the outputs of the plurality of laser beams substantially uniform based on the accurate measurement, and to obtain a uniform concentration. Can be accurately formed on the photoreceptor 405.

  Note that the magnifying lens 410 may be added to the optical scanning device 400A. In this case, the moving unit 407 moves the magnifying lens 410 to the position a or the position b simultaneously with the light receiving element 406. Others are the same as the description in FIG. 29 and FIG.

  FIG. 33 is still another schematic diagram of the optical scanning device. Referring to FIG. 33, optical scanning device 400D is the same as optical scanning device 400 except that light receiving element 411 is added to optical scanning device 400 shown in FIG.

  The light receiving element 411 is disposed on the exit surface 404A side of the fθ lens 404 and at the end in the scanning direction of the laser light.

  In electrophotography, after main scanning by the polygon mirror 403 in FIG. 33 is completed, image formation is performed by repeatedly scanning the photosensitive drum by a predetermined amount in the sub-scanning direction. Therefore, the main scanning and the sub-scanning are performed at a predetermined timing. However, a deviation occurs due to uneven rotation of the polygon mirror 403, and the deviation accumulates during the main scanning for one image. There is a risk of preventing quality image formation.

  Therefore, in the optical scanning device 400D, the light receiving element 411 that detects the laser beam scanned at the end in the main scanning direction is provided, and sub-scanning is performed in synchronization with the signal of the end of the main scanning twice, so that the polygon mirror 403 Therefore, it is possible to prevent the image quality from being deteriorated due to the rotation unevenness of the image and to perform high-quality image recording.

  FIG. 34 is a schematic diagram of an electrophotographic apparatus. Referring to FIG. 34, an electrophotographic apparatus 500 includes a photosensitive drum 501, an optical scanning device 502, a cleaning unit 503, a charging unit 504, a developing unit 505, a toner 506, a transfer unit 507, a static elimination unit. A unit 508.

  The optical scanning device 502, the cleaning unit 503, the charging unit 50, the developing unit 505, the toner 506, the transfer unit 507, and the charge eliminating unit 508 are disposed around the photosensitive drum 501.

  The optical scanning device 502 includes the optical scanning device 400 shown in FIG. 29, and forms a latent image on the photosensitive drum 501 using a plurality of laser beams by the method described above. The cleaning unit 503 removes the toner 509 remaining on the photosensitive drum 501.

  The charging unit 504 charges the surface of the photosensitive drum 501. The developing unit 505 guides the toner 506 to the surface of the photosensitive drum 501 and performs toner development on the latent image formed by the optical scanning device 502.

  The transfer unit 507 transfers the toner image. The neutralization unit 508 erases the latent image on the photosensitive drum 501.

  In the electrophotographic apparatus 500, when a series of operations is started, the charging unit 504 charges the surface of the photosensitive drum 501 and the optical scanning device 502 forms a latent image on the photosensitive drum 501 with a plurality of laser beams. Form. The developing unit 505 performs toner development on the latent image formed by the optical scanning device 502, and the transfer unit 507 transfers the toner image. As a result, the toner image is transferred onto the recording paper 510, and then the toner image is heat-fixed by a fixing unit (not shown) to complete the formation of the electrophotographic image.

  On the other hand, the static elimination unit 508 erases the latent image on the photosensitive drum 501, and the cleaning unit 503 removes the toner remaining on the photosensitive drum 501. Thereby, a series of operations are completed, and by repeating the above-described operations, it is possible to output electrophotographic images continuously and at high speed.

  In the electrophotographic apparatus 500, the optical scanning device 502 may be configured by any of the optical scanning devices 400A, 400B, 400C, and 400D.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  The present invention is applied to a surface emitting laser element capable of increasing output. The present invention is also applied to a surface emitting laser array including a surface emitting laser element capable of increasing output. Furthermore, the present invention is applied to an optical scanning device including a surface emitting laser array composed of surface emitting laser elements capable of increasing output. Furthermore, the present invention is applied to an electrophotographic apparatus using a surface emitting laser array provided with a surface emitting laser element capable of increasing output.

It is a schematic sectional drawing of the surface emitting laser element by the 1st Embodiment of this invention. FIG. 2 is a cross-sectional view of four reflective layers, two spacer layers, and an active layer 5 shown in FIG. 1. FIG. 3 is an energy band diagram of a part of two reflection layers shown in FIG. 2, two reflection layers, and a resonator (= spacer layer and active layer). It is a figure which shows the relationship between the composition ratio x of aluminum (Al), and potential energy. It is the energy band figure of the resonator and reflection layer of the conventional surface emitting laser element. It is a figure which shows the relationship between thermal conductivity and Al composition ratio x. FIG. 3 is a first process diagram showing a method for manufacturing the surface emitting laser element shown in FIG. 1. FIG. 6 is a second process diagram illustrating a method for manufacturing the surface emitting laser element illustrated in FIG. 1. FIG. 6 is a third process diagram illustrating a method for manufacturing the surface emitting laser element illustrated in FIG. 1. It is a schematic sectional drawing of the surface emitting laser element by the 2nd Embodiment of this invention. It is sectional drawing of two reflection layers shown in FIG. FIG. 11 is another cross-sectional view of two reflective layers shown in FIG. 10. FIG. 11 is an energy band diagram of a part of two reflection layers shown in FIG. 10, two reflection layers, and a resonator (= spacer layer and active layer). It is a schematic sectional drawing of the surface emitting laser element by the 3rd Embodiment of this invention. It is sectional drawing of two reflection layers shown in FIG. FIG. 15 is another cross-sectional view of two reflective layers shown in FIG. 14. FIG. 15 is an energy band diagram of a part of two reflection layers illustrated in FIG. 14, two reflection layers, and a resonator (= spacer layer and active layer). It is a figure for demonstrating the surface emitting laser element by the 4th Embodiment of this invention. It is a figure for demonstrating the modification 1 of the surface emitting laser element of FIG. It is an energy band figure in the modification 2 of the surface emitting laser element of FIG. It is a figure for demonstrating the surface emitting laser element by the 5th Embodiment of this invention. It is an energy band figure in the modification 1 of the surface emitting laser element of FIG. It is an energy band figure in the modification 2 of the surface emitting laser element of FIG. It is a figure for demonstrating the surface emitting laser element by the 6th Embodiment of this invention. It is a figure for demonstrating the modification 1 of the surface emitting laser element of FIG. It is an energy band figure in the modification 2 of the surface emitting laser element of FIG. It is a figure for demonstrating the modification 3 of the surface emitting laser element of FIG. It is a top view of the surface emitting laser array using the surface emitting laser element shown in FIG. It is the schematic of an optical scanning device. It is another schematic diagram of an optical scanning device. It is another schematic diagram of an optical scanning device. It is another schematic diagram of an optical scanning device. It is another schematic diagram of an optical scanning device. 1 is a schematic view of an electrophotographic apparatus.

Explanation of symbols

100, 100A, 100B, 100C, 100D, 100E, 200, 200A, 301 to 324... Surface emitting laser element, 101... Substrate, 102, 102A, 103, 103A, 103B, 103C, 103D, 107, 107A, 107B, 108 ... reflective layer, 104, 106 ... spacer layer, 105 ... active layer, 105A, 105C, 105E ... well layer, 105B, 105D ... barrier layer, 109 ... selective oxide layer, 109a ... non-oxidized region, 109b ... oxidized region, 110 ... Contact layer, 111 ... SiO ₂ layer, 112 ... Insulating resin, 113 ... p-side electrode, 114 ... n-side electrode, 120 ... resist pattern, 300,401 ... surface emitting laser array, 400, 400A, 400B, 400C, 400D, 502 ... optical scanning device, 402 ... collimator lens, 40 DESCRIPTION OF SYMBOLS 3 ... Polygon mirror, 404 ... f (theta) lens, 405 ... Photoconductor, 406, 409, 411 ... Light receiving element, 407 ... Moving means, 408 ... Half mirror, 410 ... Magnifying lens, 500 ... Electrophotographic apparatus, 501 ... Photoconductor drum 503: Cleaning unit, 504: Charging unit, 505 ... Development unit, 506, 509 ... Toner, 507 ... Transfer unit, 508 ... Static elimination unit, 510 ... Recording paper, 1021, 1021a, 1031, 1031a, 1031b, 1071, 1081 ... low refractive index layer, 1022, 1032, 1032a, 1032b, 1072, 1082 ... high refractive index layer, 1023, 1083 ... bonding interface, 1033, 1073 ... intermediate layer, 1034, 1074 ... intermediate layer (bonding layer), 105A, 105C, 105E ... well layer, 105B, 105 ... barrier layer.

Claims (20)

A first reflective layer comprising a semiconductor distributed Bragg reflector and formed on a substrate;
A second reflective layer formed in contact with the first reflective layer;
A resonator including an active layer and formed in contact with the second reflective layer;
A third reflective layer formed in contact with the resonator;
A fourth reflective layer formed in contact with the third reflective layer,
The resonator is made of an AlGaInPAs material,
The second reflective layer includes a stacked body in which N (N is a positive integer) first high refractive index layers and N first low refractive index layers are alternately stacked.
The third reflective layer includes a laminate in which M (M is a positive integer) second high refractive index layers and M second low refractive index layers are alternately laminated,
Each of the N first low-refractive index layers and the M second low-refractive index layers is (Al _x Ga _1-x ) _0.5 In _0.5 P (0 ≦ x ≦ 1) Consists of
Each of the N first high-refractive index layers and the M second high-refractive index layers includes (Al _y Ga _1-y ) _0.5 In _0.5 P (0 ≦ y <x ≦ 1)
One first low-refractive index layer of the N first low-refractive index layers is in contact with the resonator,
Of the N first high refractive index layers, one first high refractive index layer is in contact with an AlGaAs-based material constituting the first reflective layer,
One second low-refractive index layer of the M second low-refractive index layers is in contact with the resonator,
One of the M second high-refractive-index layers is a surface-emitting laser element in which one second high-refractive-index layer is in contact with an AlGaAs-based material constituting the fourth reflective layer. The second reflective layer is provided between the first low refractive index layer and the first high refractive index layer, and a band gap of the first low refractive index layer and the first high refractive index layer are provided. A first intermediate layer having a band gap between the refractive index layer and the band gap;
The third reflective layer is provided between the second low refractive index layer and the second high refractive index layer, and a band gap of the second low refractive index layer and the second high refractive index layer are provided. The surface emitting laser device according to claim 1, further comprising a second intermediate layer having a band gap between the refractive index layer and the band gap of the refractive index layer.   3. The surface emitting laser element according to claim 2, wherein each of the first and second intermediate layers is made of a plurality of semiconductor materials whose band gaps change stepwise. The second reflective layer is formed in contact with the resonator, and further includes a third intermediate layer having a band gap between the band gap of the resonator and the band gap of the first low refractive index layer. Including
The third reflective layer is formed in contact with the resonator, and further includes a fourth intermediate layer having a band gap between the band gap of the resonator and the band gap of the second low refractive index layer. The surface-emitting laser device according to claim 2, further comprising:   5. The surface-emitting laser element according to claim 4, wherein each of the third and fourth intermediate layers is made of a plurality of semiconductor materials whose band gaps change stepwise.   The surface emitting laser element according to claim 1, wherein in the first reflective layer, a layer in contact with the second reflective layer is an AlAs layer.   The surface emitting laser element according to claim 6, wherein the thickness of the AlAs layer is equal to or greater than resonance wavelength ÷ (refractive index of AlAs for light having resonance wavelength × 4). A first reflective layer laminated on the substrate;
A resonator formed on the first reflective layer and made of an AlGaInPAs-based material;
A second reflective layer including a laminate that is stacked on the resonator and includes a set of N (N is a positive integer) stacks of a high refractive index layer and a low refractive index layer;
A third reflective layer that is laminated on the second reflective layer and includes a layer made of an AlGaAs-based material,
The low refractive index layer is made of (Al _x Ga _1-x ) _0.5 In _0.5 P (0 ≦ x ≦ 1),
The high refractive index layer is made of (Al _y Ga _1-y ) _0.5 In _0.5 P (0 ≦ y <x ≦ 1),
The stacked body is a surface emitting laser element in which the high refractive index layer is in contact with a layer made of an AlGaAs material of the third reflective layer.   The second reflective layer includes an intermediate layer having a band gap between a band gap of the low refractive index layer and a band gap of the high refractive index layer, and further includes the low refractive index layer and the high refractive index layer. The surface emitting laser element according to claim 8, which is included between   The surface emitting laser element according to claim 9, wherein the intermediate layer includes a plurality of semiconductor layers, and the band gap changes in a stepped manner. The second reflective layer further includes a bonding layer having a band gap between a band gap of the resonator and a band gap of the low refractive index layer,
11. The surface emitting laser element according to claim 9, wherein the second reflective layer is in contact with the resonator through the bonding layer.   The surface emitting laser element according to claim 11, wherein the bonding layer includes a plurality of semiconductor layers, and a band gap changes in a stepped manner.   The surface emitting laser element according to claim 12, wherein the bonding layer includes an AlAs layer.   The surface emitting laser element according to claim 13, wherein the thickness of the AlAs layer is equal to or greater than resonance wavelength ÷ (refractive index of AlAs with respect to light of resonance wavelength × 4). Each comprises a plurality of surface-emitting laser elements comprising the surface-emitting laser element according to any one of claims 1 to 14,
The plurality of surface emitting laser elements include a plurality of first base lines arranged at equal intervals and a plurality of second base lines arranged at equal intervals and each forming a predetermined angle with the first base line. A surface emitting laser array arranged at the intersection of A surface emitting laser array according to claim 15,
A light receiving means for receiving laser light emitted from the surface emitting laser array;
An optical scanning apparatus comprising: a moving unit that moves the light receiving unit on an optical axis of the emitted laser light at a time other than the time of image recording. A surface emitting laser array according to claim 15,
A light receiving means for receiving laser light emitted from the surface emitting laser array;
An optical scanning device comprising: a light guiding unit that guides a part of the emitted laser light to the light receiving unit.   The optical scanning device according to claim 16, further comprising an enlarging unit that expands the laser beam and guides the laser beam to the light receiving unit.   The optical scanning device according to any one of claims 16 to 18, wherein the light receiving element is disposed at a terminal portion when the laser light is scanned.   An electrophotographic apparatus comprising the optical scanning device according to any one of claims 16 to 19.