JPH04363081A - Surface emitting type semiconductor laser and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent leakage of an injecting current to a buried layer and to improve a current constriction by burying a periphery of a columnar semiconductor layer for constituting a resonator with II-VI compound semiconductor epitaxial layer having a high resistance. CONSTITUTION:An n-type GaAs buffer 103 is formed on an n-type GaAs substrate 102, and a distributed reflection type multilayer film mirror 104 made of an n-type Al0.7Ga0.3As layer and an n-type Al0.1Ga0.9As layer is formed. An n-type Al0.4Gs0.6As clad layer 105, a p-type GaAs active layer 106, a p-type Al0.4Ga0.6As clad layer 107, and a p-type Al0.1Ga0.9As contact layer 108 are sequentially epitaxially grown. After an SiO2 layer 112 is formed, the layer 107 is etched to the midway except a columnar light emitting unit covered with a hard baking resist 113. After the resist 113 is removed, it is lattice- matched to GaAs, and a ZnS0.06Se0.94 layer 109 having a resistance of 1GOMEGA or more is buried and grown. Further, an SiO2/alpha-Si dielectric multilayer film 111 is formed on the surface.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-emitting conductor laser that emits laser light in a direction perpendicular to a substrate, and a method for manufacturing the same.

0002

2. Description of the Related Art A surface emitting laser having a resonator in the vertical direction of a substrate is described in the Proceedings of the 50th Academic Conference of the Japan Society of Applied Physics, Vol. 3, p. 909 29a-ZG-7 (198
Published on September 27, 2009). According to this conventional technology, as shown in FIG.
Multilayer film, (604) n-type AlGaAs cladding layer, (6
05) p-type GaAs active layer, (606) p-type AlGaA
It is formed by sequentially growing the s cladding layers. after that,
Etching leaving a cylindrical region, (607) p type,
AlGaAs is formed by liquid phase growth in the order of (608) n type, (609) p type, and (610) p type, and the periphery of the columnar region is filled. After that, (610) p-type AlGaA
A surface-emitting semiconductor laser is constructed by depositing a (611) dielectric multilayer film on top of the s cap layer and forming a (612) p-type ohmic electrode and a (601) n-type ohmic electrode. As described above, in the prior art, a pn junction consisting of (607-608) is provided in the buried layer as a means to prevent current from flowing to portions other than the active layer.

0003

However, in this p-n junction, it is difficult to obtain sufficient current confinement, and the reactive current cannot be completely suppressed. For this reason, in the conventional technology, it is difficult to perform continuous wave driving at room temperature due to heat generation of the element, and it lacks practicality. Therefore, suppression of reactive current is an important issue in surface-emitting semiconductor lasers.

Furthermore, when the buried layer has a multilayer structure for forming a p-n junction as in the past, the p-
Regarding the position of the n-interface, it is necessary to consider the position of the interface of each growth layer left in a columnar shape. Therefore, it is difficult to control the thickness of each buried growth layer in a multilayer structure, and it is extremely difficult to manufacture a surface-emitting semiconductor laser with good reproducibility.

In addition, when a buried layer is formed around a cylinder by liquid phase growth as in the conventional technique, there is a high risk that the cylinder part will break, resulting in poor yield, and improvement of properties is restricted due to structural reasons. Put it away.

Furthermore, the prior art has various problems when applied to devices such as laser printers.

[0007] In laser printers and the like, the light source (such as a semiconductor laser) used as a light source has a large light emitting spot size of several tens of micrometers, and the use of a light emitting element with strong emission intensity makes it possible to simplify the optical system and shorten the optical path length. You have more freedom in designing what you can do.

Surface-emitting semiconductor laser 1 using conventional technology
In the case of a device, the entire optical resonator is surrounded by a material with a lower refractive index than the resonator, so the light is mainly guided in the vertical direction, and the light emitting spot in the fundamental oscillation mode resonates in the horizontal direction. Even if the shape of the vessel is changed, a point light emission with a diameter of about 2 μm will result.

[0009] Therefore, attempts have been made to increase the spot size by using multiple light sources by bringing these light emitting points close to each other by about 2 μm, but in the conventional technology, resonators spaced several μm apart are connected to the LP.
Embedding by E growth is extremely difficult in terms of reproducibility, yield, etc., and manufacturing is difficult. Further, even if the resonator is buried within a distance of several μm, it is not possible to form a single spot because there is little lateral leakage of light.

[0010] Furthermore, in order to make a beam with one luminous flux from a plurality of light emitting spots and to increase the light emission intensity, it is necessary to synchronize the phases of the laser beams of each of the plurality of spots. In the prior art, it is difficult to synchronize the phases of a plurality of laser beams by bringing the laser beams close enough to each other to influence each other.

The present invention is intended to solve these problems, and its purpose is to improve the material of the buried layer so that it has a structure that allows complete current confinement and is extremely easy to manufacture. An object of the present invention is to provide a highly efficient surface emitting semiconductor laser and a method for manufacturing the same.

Another object of the present invention is to provide a surface emitting type semiconductor laser and a method for manufacturing the same, in which a plurality of light emitting parts can be placed close to each other and the phases of laser beams from each light emitting part can be synchronized. It is in.

Still another object of the present invention is to convert phase-synchronized laser beams from a plurality of light emitting parts into a single beam of light, to produce a surface-emitting type semiconductor with a large emission spot and a narrow radiation angle of the laser beam. The present invention provides a laser and a method for manufacturing the same.

[0014]

[Means for Solving the Problems] A surface-emitting semiconductor laser according to the present invention that emits light in a direction perpendicular to a semiconductor substrate has the following features:
An optical resonator comprising a pair of reflecting mirrors having different reflectances and a multilayer semiconductor layer between them, and in which at least a cladding layer of the semiconductor layers is formed in the shape of one or more columns; II embedded around the semiconductor layer of
- a Group VI compound semiconductor epitaxial layer.

[0015] The II-VI group compound semiconductor epitaxial layer is a combination of two, three, or four elements of group II elements Zn, Cd, and Hg and group VI elements O, S, Se, and Te. A semiconductor epitaxial layer can be used. Further, it is desirable that the lattice constant of the II-VI group compound semiconductor epitaxial layer matches the lattice constant of the columnar semiconductor layer. It should be noted that the semiconductor layer constituting the resonator is preferably a III-V group compound semiconductor epitaxial layer, and includes GaAs-based, GaAlAs-based, G
aAsP system, InGaP system, InGaAsP system, InG
AAs-based, AlGaAsSb-based, etc. can be suitably employed.

Since the II-VI group compound semiconductor epitaxial layer has a high resistance, there is no leakage of current injected into the buried layer formed of this high resistance layer, and extremely effective current confinement is achieved. And since the reactive current can be reduced,
It becomes possible to lower the threshold current. as a result,
It is possible to realize a surface-emitting semiconductor laser that generates little heat, and to provide a highly practical surface-emitting semiconductor laser that can perform continuous oscillation at room temperature. Further, since this buried layer does not have a multilayer structure, it can be easily formed and the reproducibility is also good. moreover,
The II-VI group compound semiconductor epitaxial layer can be formed by a method other than liquid phase growth, such as vapor phase growth, and the columnar semiconductor layer can be formed with a high yield. In addition, if vapor phase growth or the like is used, a buried layer can be reliably formed even if the buried width is narrow, which has the effect of allowing a plurality of columnar semiconductor layers to be arranged close to each other.

When the thickness of the semiconductor contact layer on the light output side of the optical resonator is 3.0 μm or less, light absorption in the contact layer can be reduced.

If the cross section of this columnar semiconductor layer parallel to the semiconductor substrate is either circular or regular polygonal, a clean circular spot beam can be obtained. Further, if either the diameter of the cross section of the columnar semiconductor layer parallel to the semiconductor substrate or the length of the diagonal line is 10 μm or less, the NFP mode becomes the zero-order fundamental mode.

When the optical resonator has one columnar semiconductor layer, the reflecting mirror on the light output side is formed within the range of the columnar end face, facing the end face. The refractive index waveguide structure in this case may be either a rib waveguide type or a buried type.

A phase-locked surface-emitting semiconductor laser has a separation groove for separating an optical resonator into a plurality of columnar semiconductor layers. A II-VI group compound semiconductor epitaxial layer is buried in this separation groove, and a light emitting portion is formed in each columnar semiconductor layer. The separation trench is prevented from reaching the active layer of the semiconductor layers constituting the optical resonator. In this way, each light emitting section influences each other via the active layer, and the phases of light in each light emitting section are synchronized.

[0021] In order to enlarge the light emitting spot, an II-V film that is transparent to the wavelength of the emitted laser light is placed in the separation groove.
Embed a Group I compound semiconductor epitaxial layer. Furthermore, a reflecting mirror on the light output side is formed over a region facing each end face of the plurality of columnar shapes and the II-VI group compound semiconductor epitaxial layer embedded in the separation trench. In this way, the region sandwiched between the columnar light emitting parts also has a vertical resonator structure, and the light leaking into that region also effectively contributes to laser oscillation, thereby expanding the light emitting spot. Furthermore, since the phase-synchronized laser beams are superimposed, the optical output increases and the radiation angle becomes smaller. In the case of GaAs lasers that are generally used as the semiconductor layer of the resonator, the II-VI group compound semiconductor epitaxial layer that is transparent to the wavelength of the laser light includes ZnSe, ZnS, ZnSSe, ZnCdS,
It can be composed of either CdSSe. When the separation groove is a groove perpendicular to the semiconductor substrate, the light incident obliquely on the separation groove can be totally reflected by utilizing the refractive index step, which increases the light confinement effect. Furthermore, if the width of the cross section of the isolation groove parallel to the semiconductor substrate is set to 0.5 μm or more and less than 10 μm, the order of the oscillation transverse mode measured from the NFP becomes the zero-order fundamental mode.

A method for manufacturing a surface-emitting semiconductor laser according to the present invention that emits light in a direction perpendicular to a semiconductor substrate includes forming multilayer semiconductor layers constituting an optical resonator on a semiconductor substrate;
A photoresist mask is formed on the semiconductor layer, at least a cladding layer of the semiconductor layer is etched using the photoresist mask to form one or more columnar semiconductor layers, and the columnar semiconductor layer is etched using the photoresist mask. It is characterized in that a buried layer is formed around the semiconductor layer by a vapor phase growth method using a II-VI group compound.

Since the vapor phase growth method is used to form the buried layer, the columnar semiconductor layer is not deformed or damaged. Furthermore, when carrying out this vapor phase growth method, if the crystal directions of the lower layer of the buried layer to be grown and formed are aligned, the I
The I-VI group compound is epitaxially grown, and a II-VI group compound semiconductor epitaxial layer is formed as a buried layer. It is preferable that the etching process leaves a portion of the cladding layer and does not expose the underlying active layer. This is because once the active layer is exposed, impurities adhere to the exposed surface and cause crystal defects.

When the photoresist mask used in the etching process is formed by reactive ion etching of a hard-baked photoresist layer, the sides of the photoresist mask are perpendicular to the semiconductor substrate. When a columnar semiconductor layer is formed by reactive ion beam etching using this photoresist mask, fine processing of the columnar semiconductor layer becomes possible, and a columnar semiconductor layer with vertical side surfaces can be formed.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing a cross section of a light emitting part of a semiconductor laser (100) in an example of the present invention, and FIG. 2 is a cross-sectional view showing a manufacturing process of the semiconductor laser in an example of the present invention.

(102) On the n-type GaAs substrate, (103
) Form an n-type GaAs buffer layer, and form an n-type Al0.7
Ga0.3 As layer and n-type Al0.1 Ga0.9 A
Thirty pairs of (104) distributed reflection type multilayer mirrors made of S-layers and having a reflectance of 98% or more for light around a wavelength of 870 nm are formed. Furthermore, (105) n-type Al0.4
Ga0.6 As cladding layer, (106) p-type GaA
s active layer, (107) p-type Al0.4 Ga0.6 A
s cladding layer, (108) p-type Al0.1 Ga0.9
An As contact layer is sequentially grown epitaxially by MOCVD (FIG. 2(a)). At this time, for example, the growth temperature is 700°C, the growth pressure is 150 Torr, organic metals such as TMGa (trimethyl gallium) and TMAl (trimethyl aluminum) are used as group III raw materials, and A is used as group V raw materials.
sH3, H2 Se as an n-type dopant, and DEZn (diethyl zinc) as a p-type dopant.

After the growth, the surface was coated with (112
) After forming the SiO2 layer, (113
) The (107) p-type Al0.4 Ga0.6 As cladding layer is etched to the middle, leaving a cylindrical light emitting part covered with hard bake resist (FIG. 2(b)). At this time, a mixed gas of chlorine and argon was used as the etching gas, the gas pressure was 1 x 10-3 Torr, and the extraction voltage was 400.
I went with V. Here, (107) p-type Al0.4 Ga
The reason why the 0.6 As cladding layer is etched only halfway is to create a rib waveguide type refractive index waveguide structure for confining horizontally injected carriers and light in the active layer.

Next (113) After removing the resist,
A (109) ZnS0.06Se0.94 layer lattice-matched to GaAs is buried and grown by MBE or MOCVD (FIG. 2(c)).

Furthermore, 4 pairs of (111)SiO on the surface
A 2/α-Si dielectric multilayer film is formed by electron beam evaporation and removed by wet etching, leaving a region slightly smaller than the diameter of the light emitting part (FIG. 2(d)). Wavelength 870n
The reflectance of the dielectric multilayer film at m is 94%.

After that, (111) a p-type ohmic electrode (110) is deposited on the surface other than the dielectric multilayer film, a (101) n-type ohmic electrode is further deposited on the substrate side, and N2
Alloying is performed at 420° C. in an atmosphere to complete a (100) surface-emitting semiconductor laser (FIG. 2(e)).

The surface-emitting semiconductor laser of this example prepared in this manner was manufactured using ZnS0.06Se0.9 used for embedding.
Since the four layers have a resistance of 1 GΩ or more and the current injected into the buried layer does not leak, extremely effective current confinement is achieved. Furthermore, since the buried layer does not need to have a multilayer structure, it can be easily grown and has high batch-to-batch reproducibility. Furthermore, the rib waveguide structure using the ZnS0.06Se0.94 layer, which has a sufficiently lower refractive index than GaAs, realizes more effective light confinement.

FIG. 3 is a diagram showing the relationship between the driving current and the oscillation light output of the surface emitting semiconductor laser according to the embodiment of the present invention. Continuous oscillation was achieved at room temperature, and an extremely low threshold value of 1 mA was obtained. The external differential quantum efficiency is also high, and suppression of reactive current contributes to improved laser characteristics.

Further, in the cross-sectional shape of the columnar portion of the surface-emitting semiconductor laser according to the embodiment of the present invention, if the shape is a circle or a regular polygon such as a regular quadrangle or a regular octagon, a spot beam will be a beautiful circle, but if the shape is not a circle Rectangular, trapezoidal, etc. shapes result in elliptical or multimode beam shapes, which are undesirable for device applications.

[0034]

[Table 1] Table 1 shows the relationship between the near-field image and the length of the cross-sectional diameter of the cylindrical portion of the surface-emitting semiconductor laser according to the example of the present invention. 1
It oscillates in the fundamental mode below 0 μm, but above that,
It oscillated in a mode higher than the first order.

The thickness of the contact layer of the surface emitting semiconductor laser according to the embodiment of the present invention is preferably 3.0 μm or less. This is because light absorption in the contact layer can be reduced. More preferably, the thickness is optimally 0.3 μm or less, resulting in low element resistance and high external differential quantum efficiency.

FIG. 4 is a perspective view showing a cross section of a light emitting part of a semiconductor laser (200) in another embodiment of the present invention.
is a semiconductor laser (200) in another embodiment of the present invention
FIG. 3 is a cross-sectional view showing the manufacturing process.

(202) On the n-type GaAs substrate, (203
) An n-type GaAs buffer layer is formed, consisting of an n-type AlAs layer and an n-type Al0.1 Ga0.9 As layer, with a wavelength of 87
Thirty pairs of (204) distributed reflection multilayer mirrors having a reflectance of 98% or more for light around 0 nm are formed. Furthermore, (205) n-type Al0.4 Ga0.6 As cladding layer, (206) p-type GaAs active layer, (207)
p-type Al0.4 Ga0.6 As cladding layer, (20
8) Epitaxially grow a p-type Al0.1 Ga0.9 As contact layer sequentially by MOCVD (Fig. 5 (
a)). At this time, for example, the growth temperature is 700°C, the growth pressure is 150 Torr, organic metals such as TMGa (trimethyl gallium) and TMAl (trimethyl aluminum) are used as group III raw materials, AsH3 is used as group V raw materials, and H2Se and p are used as n-type dopants. DEZn (diethyl zinc) was used as a mold dopant. After the growth, (212) SiO2 is formed on the surface by thermal CVD, and then a cylindrical light-emitting part covered with (213) hard-baked resist is formed by reactive ion beam etching (hereinafter referred to as RIBE). Leave (205) p-type Al0.4 Ga0.6
Etch the As cladding layer to the middle (Fig. 5(b)
)). At this time, a mixed gas of chlorine and argon was used as the etching gas, and the etching was performed at a gas pressure of 1.times.10@-3 Torr and an extraction voltage of 400 V.

Next (213) After removing the resist,
By MBE method or MOCVD method, (209)Zn
A S0.06Se0.94 layer is buried and grown (Fig. 5(c)
)).

Furthermore, 4 pairs of (211)SiO on the surface
A 2/α-Si dielectric multilayer film is formed by electron beam evaporation and removed by wet etching, leaving a region slightly smaller than the diameter of the light emitting part (FIG. 5(d)). Wavelength 870n
The reflectance of the dielectric multilayer film at m is 94%.

Thereafter, (211) a p-type ohmic electrode (210) is deposited on the surface other than the dielectric multilayer film, and an n-type ohmic electrode (201) is further deposited on the substrate side, and N2
Alloying is performed at 420° C. in an atmosphere to complete a surface emitting semiconductor laser (FIG. 5(e)).

The surface-emitting semiconductor laser of this example prepared in this manner was manufactured using ZnS0.06Se0.9 used for embedding.
Since the four layers have a resistance of 1 GΩ or more and the current injected into the buried layer does not leak, extremely effective current confinement is achieved. Furthermore, since the buried layer does not need to have a multilayer structure, it can be easily grown and has high batch-to-batch reproducibility. Furthermore, more effective light confinement is achieved by using a ZnS0.06Se0.94 layer, which has a sufficiently lower refractive index than GaAs, and a buried refractive index waveguide structure in which the active layer is embedded.

Further, in the embodiment of the present invention, the active layer is made of GaA.
s, but the same effect can be obtained with AlGaAs. Furthermore, even when other III-V group compound semiconductors are used for the columnar portions, similar effects can be obtained by selecting an appropriate II-VI group compound semiconductor for the buried layer.

FIGS. 6 and 7 show other embodiments of the present invention,
FIG. 6 is a schematic diagram showing a cross section of a light emitting part of a phase-locked semiconductor laser (300) that can enlarge a light emitting spot, and FIG.
FIG. 2 is a cross-sectional view showing the manufacturing process.

(302) n-type GaAs substrate, (303
) Form an n-type GaAs buffer layer, and form an n-type Al0.9
Ga0.1 As layer and n-type Al0.2 Ga0.8 A
(304) consisting of 25 pairs of S-layers with a reflectance of 98% or more for light with a wavelength of 780 nm and ±30 nm.
Form a semiconductor multilayer mirror. Furthermore, (305)n
Type Al0.5 Ga0.5 As cladding layer, (306
) p-type Al0.13Ga0.87As active layer, (30
7) p-type Al0.5 Ga0.5 As cladding layer, (
308) Epitaxially grow p-type Al0.15Ga0.85As contact layer sequentially by MOCVD method (Fig. 7
(a)). The growth conditions at this time are, for example, the growth temperature is 72
The growth was performed at 0°C and at a pressure of 150 Torr, using organic metals such as TMGa (trimethyl gallium) and TMAl (trimethyl aluminum) as group III raw materials, AsH3 as group V raw materials, H2 Se as n-type dopant, and DEZn as p-type dopant. (diethyl zinc) was used.

After the growth, the surface was coated with (3
12) Form a SiO2 layer, coat a photoresist on top of it, and bake it at a high temperature (313) to form a hard baked resist. Furthermore, a SiO2 layer is formed on this hard-baked resist by EB evaporation.

Next, reactive ion etching method (hereinafter referred to as R
Each layer formed on the substrate is etched using a method (referred to as IE method). First, a commonly used photolithography process is performed on the SiO2 layer formed on the (313) hard bake resist to form the necessary resist pattern, and using this pattern as a mask, the SiO2 layer is
Etch two layers. For example, RIE is performed using CF4 gas with a gas pressure of 4.5 Pa, an input RF power of 150 W, and a sample holder controlled at 20°C. Next, using this SiO2 layer as a mask, the hard baked resist (313) is etched by RIE method. For example, RIE is performed using O2 gas with a gas pressure of 4.5 Pa, an input power of 150 W, and a sample holder controlled at 20°C. At this time, the resist pattern initially formed on the SiO2 layer is also etched at the same time. Next, etching is performed again using CF4 gas in order to simultaneously etch the SiO2 layer remaining in the pattern and the (312) SiO2 layer formed on the epitaxial layer. As described above, using the thin SiO2 layer as a mask, the RIE method (31
3) By using it in a hard-baked resist, it is possible to create a hard-baked resist that has the necessary pattern shape and also has (313) side surfaces perpendicular to the substrate (FIG. 7(b)).

Using this (313) hard bake resist with vertical sides as a mask, a reactive ion beam etching method (hereinafter referred to as RIBE method) was used to leave columnar light emitting parts (307)p. Type Al0.5 Ga0.
5 Etch halfway through the As cladding layer (Fig. 7
(c)). At this time, for example, a mixed gas of chlorine and argon is used as the etching gas, and the gas pressure is 5 x 10-4 Torr.
The plasma extraction voltage was 400 V, the ion current density on the etching sample was 400 μA/cm 2 , and the sample holder was kept at 20° C. Here, the reason why the (307) p-type Al0.5 Ga0.5 As cladding layer is etched only halfway is because the horizontally injected carriers and optical confinement of the active layer are achieved by the refractive index guided rib waveguide structure. This is to allow part of the light within the active layer to be transmitted in the horizontal direction of the active layer.

In addition, by using the RIBE method in which etching is performed by irradiating a beam of ions perpendicularly to a (313) hard bake resist having vertical side surfaces and an etching sample, it is possible to form a (320) light emitting part in close proximity to each other. can be separated by a (314) separation groove perpendicular to the substrate, and it is also possible to create a vertical optical resonator necessary for improving the characteristics of a surface-emitting semiconductor laser.

Next (313) After removing the hard bake resist, A
II-VI lattice matched to l0.5 Ga0.5 As
(309)Z as a group compound semiconductor epitaxial layer
An nS0.06Se0.94 layer is buried and grown (Fig. 7 (
d)). This (309) layer is transparent to the oscillation wavelength of the (300) surface-emitting semiconductor laser.

Furthermore, after removing the (312) SiO2 layer and the polycrystalline ZnSSe formed on it, four pairs of (311) SiO2/a-Si dielectric multilayer film reflectors were deposited on the surface by electron beam evaporation. A part of the light emitting part (320) formed and separated using dry etching, and a part of the light emitting part (32)
0) Remove leaving the buried layer sandwiched between the light emitting parts (Figure 7)
(e)). The reflectance of the dielectric multilayer mirror at a wavelength of 780 nm is 95% or more. embedded with ZnSSe (
314) By creating a (311) dielectric multilayer reflector on the separation groove, a vertical resonator structure is also formed in the area sandwiched between the light emitting parts, and the light leaking into the (314) separation groove can also be effectively used as a laser beam. In order to contribute to oscillation and utilize leaked light, (
320) Light emission is synchronized with the phase of the light emitting section.

After that, (310) a p-type ohmic electrode is deposited on the surface other than the (311) dielectric multilayer reflector,
Furthermore, a (301) n-type ohmic electrode was deposited on the substrate side, and alloying was performed at 420°C in an N2 atmosphere.
00) Complete a surface emitting semiconductor laser (FIG. 7(f)). Here, the (310) n-type ohmic electrode on the emission side is formed so as to be electrically connected to each (308) contact layer of each (320) light emitting section.

The surface-emitting semiconductor laser of this example fabricated in this manner uses a ZnSSe epitaxial layer for the (309) buried layer, thereby replacing the previously used AlG
It has a resistance of 1 GΩ or more, which is higher than the current block structure that uses reverse bias of the p-n junction of the aAs layer, and has an optimal current block structure, and the buried layer absorbs the oscillation wavelength of 780 nm. Since it is a transparent material that does not have any (320) light, leakage light from the light emitting part can be used effectively.

FIG. 8 shows the shape of the light emitting side of the conventional surface emitting type semiconductor laser and the surface emitting type semiconductor laser of this embodiment, and the intensity distribution of NFP during laser oscillation. FIG. 8(a) shows the resonator (620) of the conventional surface-emitting semiconductor laser (600) shown in FIG.
607-608) The case is shown in which the GaAlAs epitaxial layer is brought close to about 5 μm, which is a distance that allows embedding. There is a dielectric multilayer reflector and a p-type ohmic electrode on the emission surface of the laser, but these are removed in the figure for comparison of the shape of the resonator. Figure 8(b) is
(a) shows the NFP intensity distribution between a and b. Even if multiple light-emitting parts (620) of conventional surface-emitting semiconductor lasers are brought close enough to be embedded, only multiple light-emitting spots will appear, and there is no lateral light leakage, so multimodal NFP is possible. Therefore, there is no single light emitting spot.

FIG. 8(c) shows the shape of the surface-emitting semiconductor laser of this example, in which the separation groove is (409)NnS0.06
The separation groove is filled with a Se0.94 layer and is filled by vapor phase growth, so the minimum width of the separation groove is 1 μm. Figure 8(d) is
(c) NFP between c and d. (314) Since light is also emitted from above the separation groove, the light emitting point spreads, which is NF.
It can be seen from P. Furthermore, since the phases of adjacent laser beams are synchronized, the optical output increases and a circular beam with a radiation angle of 1° or less can be obtained.

Table 2 shows the relationship between the width of the (314) separation groove of the (300) surface-emitting semiconductor laser of the example and the oscillation transverse mode order measured from the NFP.

[0056]

[Table 2] If the width is narrower than 10 μm, the phase-locked laser's oscillation transverse mode oscillates in the fundamental mode, but if the width is narrower than 10 μm, the laser oscillates in higher-order modes such as the first order or higher, and the radiation angle becomes wider and the beam shape changes. Since it becomes elliptical, it is not preferred in terms of application. Furthermore, if the separation groove is narrower than 0.5 μm, it tends to be difficult to obtain a circular beam.

In the above embodiment, a semiconductor laser having a single optical resonator in which a plurality of light emitting parts are separated is described, but a plurality of such optical resonators may be formed on the same semiconductor substrate. can. If p-type ohmic electrodes on the light output side are independently provided for each optical resonator, the laser beams from each optical resonator can be turned ON, OFF, and modulated independently.

In the above embodiments, a GaAlAs-based surface-emitting type semiconductor laser has been described, but as mentioned above, it can also be suitably applied to other III-V-based surface-emitting type semiconductor lasers. is Ga0.87Al
The oscillation wavelength can also be changed by changing the composition of not only 0.13As but also Al.

Further, although this embodiment has been described based on the structure shown in FIG. 6 and the structure of the light emitting section shown in FIG. 8(c), the present invention is not limited to this. Figures 9 to 11
2 shows another embodiment of the present invention, and is a schematic diagram of the light emitting part showing the shape of the optical resonator and the plane horizontal to the substrate of the separation groove fabricated inside the resonator as seen from the light emitting side, respectively. be. In FIGS. 9A to 9J and 9M, a plurality of columnar semiconductor layers each having a circular or regular polygonal horizontal cross section are formed on a substrate, and these are arranged in line symmetry. In either case, the light emitting spot can be expanded compared to one with a single light emitting part. When obtaining a relatively large beam diameter laser beam with one luminous flux from each light emitting part and separation groove,
) and (l), a circular beam can be obtained even if the cross-sectional shape of each light emitting part is a shape other than a circle or a regular polygon. It is sufficient that the contour shape connecting the outer edges of each of the non-circular and non-regular polygonal light emitting portions arranged line-symmetrically has a shape close to a circle or a regular polygon. In addition, FIGS. 10(a) to (d),
In the embodiments shown in FIGS. 11(a) to 11(c), n light emitting parts are formed, and in this embodiment as well, the same effect as the embodiment shown in FIG. The effect is that the spot can be made into any size and shape. In both of the devices shown in FIGS. 10 and 11, a line beam can be obtained by arranging a plurality of light emitting sections at equal intervals in rows and/or columns on a two-dimensional plane parallel to the substrate.

In the embodiment shown in FIG. 6, (31
0) It is also possible to manufacture a semiconductor laser in which p-type ohmic electrodes are provided separately in the number of (320) light emitting parts and each is connected to a (308) contact layer. In this case, a plurality of light emitting portions are formed on the same substrate, each of which can independently turn ON, OFF, and modulate a circular beam, and the wavelengths of the beams are synchronized.

Furthermore, the scope of application of the surface-emitting semiconductor laser of the present invention is not limited to printing devices such as printers and copying machines.
Needless to say, facsimiles and displays have exactly the same effect.

[0062]

[Effects of the Invention] As explained above, according to the surface-emitting semiconductor laser according to the present invention, the periphery of the columnar semiconductor layer constituting the resonator is embedded with a high-resistance II-VI group compound semiconductor epitaxial layer. Therefore, the current injected into the buried layer does not leak, and extremely effective current confinement is achieved. Since the reactive current can be reduced, the threshold current can be lowered. As a result, it is possible to realize a surface-emitting semiconductor laser that generates less heat, and to provide a highly practical surface-emitting semiconductor laser that is capable of continuous oscillation at room temperature. Further, since this buried layer does not have a multilayer structure, it can be easily formed and the reproducibility is also good.

According to the manufacturing method of the present invention, since the buried layer of the II-VI group compound of the surface-emitting semiconductor laser of the present invention is formed by vapor phase growth, there is no need to deform or damage the columnar semiconductor layer. Therefore, the yield can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a cross section of a light emitting part of a semiconductor laser in an embodiment of the present invention.

2A to 2E are cross-sectional views showing the manufacturing process of the semiconductor laser of FIG. 1;

FIG. 3 is a diagram showing the relationship between drive current and oscillation light output of the semiconductor laser in FIG. 1;

FIG. 4 is a perspective view showing a cross section of a light emitting part of a semiconductor laser in another embodiment of the present invention.

5A to 5E are cross-sectional views showing the manufacturing process of the semiconductor laser of FIG. 4;

FIG. 6 is a schematic diagram showing a cross section of a light emitting part of a phase-locked surface-emitting semiconductor laser according to an embodiment of the present invention.

7A to 7F are cross-sectional views showing the manufacturing process of the semiconductor laser of FIG. 6;

FIG. 8 is a diagram showing the difference in shape and near-field image of light emission between a conventional surface-emitting semiconductor laser and the semiconductor laser in FIG. The figure shows the shape of the emitted side, and figure (b) is similar to figure (a).
The intensity distribution of the emission far-field image of the semiconductor laser shown in FIG. Figure (c) shows an example of the shape of the light emitting side of the semiconductor laser in this example, and Figure (d) shows the far field of light emission of the semiconductor laser shown in Figure (c). This shows the intensity distribution of the image.

FIGS. 9A to 9M are schematic diagrams showing the shape of the light emitting side of a phase-locked surface-emitting semiconductor laser according to another embodiment of the present invention.

FIGS. 10(a) to 10(d) are schematic diagrams showing the shape of the light emitting side of a phase-locked surface-emitting semiconductor laser in another embodiment of the present invention.

FIGS. 11A to 11C are schematic diagrams showing the shape of the light emitting side of a phase-locked surface-emitting semiconductor laser in another embodiment of the present invention.

FIG. 12 is a perspective view showing a light emitting section of a conventional surface emitting semiconductor laser.

[Explanation of symbols]

102, 202, 302 Semiconductor substrate 106, 206
, 306 Active layer 107, 207, 307 Cladding layer 108, 208
, 308 contact layer 109, 209, 309
II-VI group compound semiconductor epitaxial layer 111, 211, 311 Light exit side reflecting mirror 314
Separation groove 320 Light emitting part

Claims (16)

[Claims] 1. A surface-emitting semiconductor laser that emits light in a direction perpendicular to a semiconductor substrate, comprising a pair of reflecting mirrors with different reflectances and multiple semiconductor layers between them, wherein one of the semiconductor layers is an optical resonator in which at least one cladding layer is formed in the shape of one or more columns, and a group II-VI compound semiconductor epitaxial layer embedded around the columnar semiconductor layer. Surface-emitting semiconductor laser. 2. In claim 1, the II-VI group compound semiconductor epitaxial layer comprises Z, which is a group II element.
n, Cd, Hg and group VI elements O, S, Se, T
A surface-emitting semiconductor laser characterized in that it is a semiconductor epitaxial layer in which e is a combination of two elements, three elements, or four elements. 3. In claim 1 or 2, the II-
1. A surface-emitting semiconductor laser, wherein a lattice constant of the Group VI compound semiconductor epitaxial layer matches a lattice constant of the columnar semiconductor layer. [Claim 4] In any one of claims 1 to 3,
A cross section of the columnar semiconductor layer parallel to the semiconductor substrate is
A surface-emitting semiconductor laser characterized by being either circular or regular polygonal. 5. The surface-emitting semiconductor laser according to claim 4, wherein either a diameter of a cross section parallel to the semiconductor substrate or a length of a diagonal line of the columnar semiconductor layer is 10 μm or less. [Claim 6] In any one of claims 1 to 5,
A surface emitting semiconductor laser characterized in that the thickness of the semiconductor contact layer on the light emitting side of the optical resonator is 3.0 μm or less. [Claim 7] In any one of claims 1 to 6,
The optical resonator has a separation groove that separates the plurality of columnar semiconductor layers, and the II-VI group compound semiconductor epitaxial layer is embedded in the separation groove, and each of the columnar semiconductor layers has a separation groove. A surface emitting device characterized in that a light emitting section is formed, the separation groove does not reach an active layer of the semiconductor layers constituting the optical resonator, and the phase of light in each light emitting section is synchronized. type semiconductor laser. 8. The surface-emitting semiconductor laser according to claim 7, wherein the separation groove is a groove perpendicular to the semiconductor substrate. 9. In claim 7 or 8, the separation groove includes the II which is transparent to the wavelength of the emitted laser beam.
- a group VI compound semiconductor epitaxial layer is embedded;
The reflecting mirror on the light exit side is formed over a region facing each end face of the plurality of columnar shapes and the II-VI group compound semiconductor epitaxial layer embedded in the separation groove. Surface-emitting semiconductor laser. 10. In claim 9, the II-VI
Group compound semiconductor epitaxial layer is ZnSe, ZnS
, ZnSSe, ZnCdS, or CdSSe. 11. In any one of claims 7 to 10, the width of a cross section of the isolation trench parallel to the semiconductor substrate is:
A surface emitting semiconductor laser characterized in that the diameter is 0.5 μm or more and less than 10 μm. 12. A method for manufacturing a surface-emitting semiconductor laser that emits light in a direction perpendicular to a semiconductor substrate, comprising: forming a multilayer semiconductor layer constituting an optical resonator on a semiconductor substrate;
A photoresist mask is formed on the semiconductor layer, at least a cladding layer of the semiconductor layer is etched using the photoresist mask to form one or more columnar semiconductor layers, and the columnar semiconductor layer is etched using the photoresist mask. 1. A method for manufacturing a surface emitting semiconductor laser, comprising forming a buried layer around a semiconductor layer by a vapor phase growth method using a II-VI group compound. 13. In claim 12, the II-V
By implementing a vapor phase growth method using a Group I compound, the above II
- A method for manufacturing a surface emitting semiconductor laser, characterized in that a group VI compound is epitaxially grown to form a group II-VI compound semiconductor epitaxial layer. 14. The method of manufacturing a surface emitting semiconductor laser according to claim 12 or 13, wherein the etching step is completed leaving a part of the cladding layer and does not expose an underlying active layer. 15. In any one of claims 12 to 14, the photoresist mask is formed by reactive ion etching of an exposed photoresist layer, and the side surfaces of the photoresist mask are perpendicular to the semiconductor substrate. A method of manufacturing a surface emitting semiconductor laser, characterized in that: 16. The method according to claim 15, wherein the columnar semiconductor layer is formed by reactive ion beam etching using the photoresist mask, and a side surface of the columnar semiconductor layer is perpendicular to the semiconductor substrate. A method for manufacturing a surface-emitting semiconductor laser.