JP2007299949A - Semiconductor light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light emitting element capable of suppressing a deterioration in optical output. <P>SOLUTION: The semiconductor light-emitting element comprises an n-type DBR layer 13 for reflecting a light having a constant wavelength; a light emitting region layer 17 having a light emitting layer 15 for emitting the light having the same wavelength formed on the n-type DBR layer 13; a high-resistance region 20 formed on the side of the layer 17 by a proton injection; a p-type DBR layer 22 contacting on the layer 17 and the region 20, having a proton diffused in the vicinity of the interface with the region 20 and substantially having a function of a current diffusion, and reflecting the light having the identical wavelength; a p-side electrode 25 formed on the p-type DBR layer 22 and over the layer 17 through a p-type contact layer 24; and an n-side electrode 29 formed under the n-type DBR layer 13 opposite to the p-side electrode 25. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device.

  In recent years, light emitting diodes (LEDs) and semiconductor lasers (LDs) using III-V compound semiconductors have been used in optical communication devices, multimedia-related devices, LED display panels, etc., and have been rapidly spreading. ing.

  Optical communication is generally known as long-distance (trunk system, etc.) large-capacity optical communication using an optical element having a wavelength in the infrared region and a silica-based optical fiber. However, in recent years, short-distance optical communication of about 10 to 100 m using an optical element including a visible light LED and a plastic optical fiber (POF) has attracted attention. Above all, since the low-loss area of low-cost acrylic polymer POF is in the red wavelength band, for example, the 660 nm band, for high-speed POF data link applications such as home network, in-vehicle LAN, FA (Factory Automation) equipment, High speed and low price of red semiconductor light emitting devices are expected.

  Therefore, a resonant cavity type LED (RC type LED) is expected as a group III-V compound semiconductor light-emitting device for visible light short-distance optical communication having a transmission rate of 500 M to 1 Gbps. This RC type LED is a light emitting device that has a characteristic that can be said to be intermediate between a vertical cavity surface emitting laser (VCSEL) and a conventional LED, and its development for high-speed response is progressing. It has been.

  For example, as a high-speed semiconductor light emitting element, a lower DBR (Distributed Bragg Reflector) layer, a light emitting layer that emits light by current injection formed on the lower DBR layer, and a light emitting layer that is formed on the light emitting layer and reflects more than the lower DBR layer An upper DBR layer having a low rate, a current diffusion layer formed on the upper DBR layer, and a contact layer having a narrower band gap than the current diffusion layer formed on the current diffusion layer. A light-emitting element including a layer and a high-resistance region formed by injecting protons into the light-emitting layer is disclosed (see, for example, Patent Document 1).

Although the disclosed semiconductor light-emitting device has high-speed response, if light is continuously emitted by current injection, the light output decreases, and the standard required for high-speed POF data link applications, etc., in a relatively short time. There is a fear that it cannot be satisfied. In particular, under high temperature and high humidity conditions, it has been found that the time required to decrease the light output is even shorter.
JP 2004-281559 A

  The present invention provides a semiconductor light emitting device capable of suppressing degradation of light output.

  A semiconductor light-emitting element of one embodiment of the present invention includes a first reflective film that reflects light having a certain wavelength and a light-emitting layer that is formed on the first reflective film and emits light having the wavelength. A region layer, a high-resistance region formed by ion implantation on a side of the light-emitting region layer, and in contact with the light-emitting region layer and the high-resistance region, diffused in the vicinity of the interface with the high-resistance region A second reflective film having the implanted element and reflecting the light of the wavelength; and a first reflective film formed on the second reflective film and above the light emitting region layer via a contact layer. An electrode and a second electrode formed below the first reflective film on the side opposite to the first electrode are provided.

  According to another aspect of the present invention, there is provided a semiconductor light emitting device including a first reflective film that reflects light having a certain wavelength, and a light emitting layer that emits light having the wavelength formed on the first reflective film. A light emitting region layer having a light emitting region layer, a second reflective film that is in contact with the light emitting region layer and reflects the light of the wavelength, and a side portion of the light emitting region layer and the second reflective film is formed by ion implantation. A high-resistance region, a current diffusion layer having the implanted element in contact with the second reflective film and the high-resistance region and diffused in the vicinity of the interface with the high-resistance region; and A first electrode formed on the light emitting region layer via a contact layer, and a second electrode formed below the first reflective film on the opposite side of the first electrode. And an electrode.

  According to another aspect of the present invention, there is provided a semiconductor light emitting device having a first current diffusion layer and a light emitting region layer formed on the first current diffusion layer and emitting a light having a predetermined wavelength. And a high resistance region formed by ion implantation on the side of the light emitting region layer, and the implantation diffused in the vicinity of the interface with the high resistance region in contact with the light emitting region layer and the high resistance region A second current diffusion layer having an element; a first electrode formed on the second current diffusion layer and above the light emitting region layer through a contact layer; and the first electrode, And a second electrode formed below the first current diffusion layer on the opposite side.

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor light-emitting device which can suppress deterioration of optical output can be provided.

  The inventors examined the deterioration phenomenon of the semiconductor light emitting device in a high temperature and high humidity environment, and obtained the following knowledge. The studied semiconductor light emitting device 101 is an RC type LED having a structure similar to the structure of the semiconductor layer described in Patent Document 1, as shown in FIG. A ring-shaped portion in contact with both 120 and the p-type contact layer 124, and an electrode 125 having a cross-shaped thin wire connected to the inside of the ring are formed.

  The semiconductor light emitting device 101 can be confirmed to be altered in the semiconductor layer in the vicinity of the p-side electrode 125 when the energization is deteriorated. It has been confirmed that this alteration is so-called oxidation in which the surface of the semiconductor layer that has reached a high temperature has reacted with moisture. Oxidation starts from the thin line portion of the p-side electrode 125 on the surface.

  The mechanism of oxidation is assumed as follows. The semiconductor light emitting device 101 has a structure in which a current is efficiently supplied to the inside of the light emitting region with a p-side electrode on the surface as a thin line structure in order to obtain high light output. Since the peripheral portion of the ring-shaped p-side electrode 125 is in contact with the high resistance region 120, the injected current is concentrated on the inside of the ring-shaped p-side electrode 125 and the cross-shaped thin line portion. As a result, local heat generation occurs inside the p-side electrode 125 and in the cross-shaped thin line portion, and at the same time, generation and migration of ions due to current occur. That is, it is considered that hydroxide ions and oxygen ions in water adhering to the surface of the semiconductor light emitting element 101 penetrate from the surface by an electric field due to current, Joule heat is also added, and heat generation promotes alteration due to oxidation. It is done.

  This alteration of the semiconductor layer due to oxidation is not limited to the RC type LED, but may also occur in an LED that does not include a VCSEL or a conventional DBR layer.

In the following description, the resonance wavelength λ _FP and the PL light emission wavelength (the light emission wavelength from the light emitting layer) λ _PL are assumed to be equal to facilitate understanding. Strictly speaking, however, the PL emission wavelength λ _PL shifts to a longer wavelength as the temperature increases. The resonance wavelength λ _FP due to the DBR layer also shifts to a longer wavelength as the temperature rises. Since towards the shift of lambda _PL is larger than the shift of the lambda _FP, as both wavelengths coincide at a certain temperature, it is adjusted somewhat longer wavelength (5 to 10 nm) than the _PL to lambda _FP at room temperature lambda.

  Examples of the present invention obtained based on the above knowledge will be described below with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals.

  A semiconductor light emitting device according to Example 1 of the present invention will be described with reference to FIGS. FIG. 1 is a diagram schematically showing the structure of a semiconductor light emitting device, FIG. 1 (a) is a sectional view in the front direction, FIG. 1 (b) is a plan view of the semiconductor light emitting device viewed from above, and a line AA. A part of the cross section along the line corresponds to the cross sectional view of FIG. FIG. 2 is a cross-sectional view schematically showing the manufacturing process of the semiconductor light emitting device in the order of steps. FIG. 3 is a diagram schematically showing the flow of injection current of the semiconductor light emitting device.

  As shown in FIG. 1A, the semiconductor light emitting device 1 includes an n-type DBR layer that is a first reflective film formed on the main surface of an n-type GaAs substrate 11 via an n-type buffer layer 12. 13, a light emitting region layer 17 composed of an n-type cladding layer 14, a light emitting layer 15 and a p-type cladding layer 16 sequentially formed on the n-type DBR layer 13, a side portion of the light emitting region layer 17, and the n-type DBR layer 13. A p-type DBR layer 22 as a second reflective film having a function of current diffusion formed on and in contact with the high-resistance region 20, the light-emitting region layer 17 and the high-resistance region 20 formed by proton implantation. A p-side electrode 25 that is a first electrode formed on the p-type DBR layer 22 and above the light emitting region layer 17 via a p-type contact layer 24, and the side opposite to the p-side electrode 25 Formed on the lower side (back side) of the n-type GaAs substrate 11 The n-side electrode 29 is a second electrode has as main components.

On the main surface of the n-type GaAs substrate 11, an n-type buffer layer 12 made of GaAs is formed. The n-type DBR layer 13 is AlGaAs-based, that is, a structure in which Al _0.5 Ga _0.5 As and Al _0.95 Ga _0.05 As are alternately stacked, and the number of repetitions is 40 pairs (see later). . The n-type and p-type cladding layers 14 and 16 are n-type and p-type In _0.5 (Ga _0.5 Al _0.5 ) _0.5 P, respectively. The light emitting layer 15 has an undoped InGaAlP-based MQW structure adjusted so that an emission peak wavelength is about 665 nm.

  The light emitting region layer 17 is a region formed of the light emitting layer 15 and the n-type and p-type clad layers 14 and 16 having a diameter of 100 μm in a planar shape and a three-dimensional columnar shape. A part of the high resistance region 20 surrounds this cylindrical region at a position parallel to the light emitting region layer 17, and part of the high resistance region 20 from the light emitting region layer 17 side above the n-type DBR layer 13. It is formed continuously. The high resistance region 20 is increased in resistance by selectively ion-implanting protons from the light emitting region layer 17 side. Therefore, a portion continuous with the light emitting region layer 17 at a position parallel to the light emitting region layer 17 has the same main component as the light emitting region layer 17, and on the light emitting region layer 17 side above the n-type DBR layer 13. The portion formed continuously from the above has the same main component as the n-type DBR layer 13. Note that a portion extending to the n-type DBR layer 13 below the high resistance region 20 may be suppressed to a minimum.

  The p-type DBR layer 22 is directly above and in contact with the light emitting region layer 17 and the high-resistance region 20, has a laminated structure doped with p-type with the same composition as the n-type DBR layer 13, and the number of repetitions is 10 pairs. The film thickness is about 1 μm. As will be described later, the p-type DBR layer 22 in contact with the high-resistance region 20 is not affected by proton ion implantation, and has a degree of proton diffusion due to the influence of heat during crystal growth.

The n-type and p-type DBR layers 13 and 22 optically reflect Al _0.5 Ga _0.5 As having a high refractive index and Al _0.95 Ga _0.05 As having a low refractive index. The film thicknesses are alternately stacked so that the film thickness is ¼ of the optical wavelength of the power. The lower n-type DBR layer 13 has a reflectance of 99.9% or more, and the upper p-type DBR layer 22 that emits light has a reflectance of about 95%. In addition, the n-type and p-type DBR layers 13 and 22 are electrically high in concentration of 2 to 4 × 10 ¹⁸ cm ⁻³ , the n-type DBR layer 13 is made of silicon, and the p-type DBR layer 22 is made of Carbon is doped to reduce the resistance.

The p-type contact layer 24 is formed by doping a GaAs layer with carbon as an impurity at a high concentration of 2 × 10 ¹⁹ cm ⁻³ and having a film thickness of about 20 nm. The p-type contact layer 24 has a low resistance to the injection current and is formed thin in order to suppress absorption of the emission wavelength.

  As shown in FIG. 1B, the p-side electrode 25 is made of AuZn as a main material, and the p-type contact layer 24 and an ohmic contact are formed. The inner diameter of the ring-shaped electrode is 95 μm and the width is 5 μm, and the cross-shaped thin wire inside the ring has a width of 3 μm. The p-side electrode 25 is connected to a bonding pad 26 that is disposed close to the p-side electrode 25. The ring-shaped p-side electrode 25 overlaps the boundary between the circular light emitting region layer 17 and the high resistance region 20 so that the centers thereof substantially coincide with each other when viewed from above. The n-side electrode 29 has an ohmic contact formed on the entire surface with AuGe as the main material after adjusting the substrate thickness on the opposite side of the main surface of the n-type GaAs substrate 11.

  Next, a method for manufacturing the semiconductor light emitting element 1 will be described. First, as shown in FIG. 2A, the first crystal growth is performed. On the main surface of the n-type GaAs substrate 11, an n-type buffer layer 12, an n-type DBR layer 13, an n-type cladding layer 14, a light emitting layer 15, and a p-type cladding layer 16 are sequentially grown. For example, the n-type InGaP adjustment layer 18 having a thickness of about 0.7 μm and the n-type GaAs protective layer 19 having a thickness of about 0.1 μm are formed by MOCVD (metal organic chemical vapor deposition).

In the MOCVD method, In material is trimethylindium (TMI), Ga material is trimethylgallium (TMG), Al material is trimethylaluminum (TMA), As material is arsine (AsH ₃ ), P material is phosphine (PH ₃ ), etc. A well-known method using an organic metal raw material and a semiconductor material gas is employed. Silane (SiH ₄ ) can be used as the n-type dopant material, and dimethylzinc (DMZ) or carbon tetrabromide (CBr ₄ ) can be used as the p-type dopant material.

As shown in FIG. 2B, a mask layer 31 made of, for example, a silicon oxide film is formed on the n-type GaAs protective layer 19 in a circular region with a diameter of 100 μm to be a light emitting region, and the n-type GaAs protective layer is formed. Proton ions are implanted from above 19. At this time, the acceleration energy of ion implantation is set to 150 keV, for example. The film thicknesses of the n-type InGaP adjustment layer 18 and the n-type GaAs protective layer 19 are adjusted so that the proton concentration peaks in the n-type cladding layer 14 and the light emitting layer 15. The resistance of the pn junction portion in the light emitting region layer 17 is increased. In addition, the dose amount was set to 1 × 10 ¹⁵ cm ⁻² , for example.

  As shown in FIG. 2C, the mask layer 31, the n-type InGaP adjustment layer 18, and the n-type GaAs protective layer 19 are sequentially etched away. The light emitting region layer 17 in which protons are shielded by the mask layer 31 is formed, and at the same time, the high resistance region 20 into which protons are implanted is selectively formed.

  As shown in FIG. 2D, the second crystal growth is performed. A p-type DBR layer 22 and a p-type contact layer 24 made of GaAs are sequentially formed on the flat p-type cladding layer 16 and the high resistance region 20 exposed on the surface by MOCVD. Further, a protective layer (not shown) made of, for example, n-type InGaAlP is formed on the p-type contact layer 24.

  In the second crystal growth, it is necessary to maintain the quality of the newly grown crystal while maintaining the high resistance region 20 formed in the previous step. That is, crystal growth in a temperature range that is not low enough to deteriorate the crystallinity of the p-type DBR layer 22 and the p-type contact layer 24 without increasing the temperature so that protons in the high-resistance region 20 diffuse. The selected temperature range is 500-550 ° C.

  According to the study by the inventors, the above-mentioned or similar proton implantation condition sample undergoes a recovery phenomenon when the temperature rises above about 550 ° C., and the resistivity decreases. In other words, after ion implantation, only a process at a temperature of 550 ° C. or lower is possible.

The p-type DBR layer 22 stacked in the second crystal growth is a reflective layer on the light extraction side and a layer intended for electrical conduction, and the p-type contact layer 24 is a layer intended for electrical conduction. Therefore, for example, it is not always necessary to be a high quality crystal like the light emitting region layer 17 including the light emitting layer 15. In order to make the light emitting region layer 17 a high-quality crystal, for example, it is necessary to grow it at 700 ° C., but the p-type DBR layer 22 and the p-type contact layer 24 function sufficiently even if grown at 500 ° C. It was found. Moreover, AlGaAs and GaAs can be doped with a high concentration of carbon even at a relatively low temperature, and the supply amount of arsine (AsH ₃ ) is adjusted by obtaining the knowledge that AlGaAs and GaAs are suitable for p-type electrically conductive layers. Then, auto doping of carbon of the organic metal itself is performed, and the AlGaAs p-type DBR layer 22 is doped to 2 × 4 ¹⁸ cm ⁻³ and the p-type contact layer 24 made of GaAs is doped to 2 × 10 ¹⁹ cm ⁻³ . Went.

  After the second crystal growth, the protective layer is removed, and a ring-shaped p-side electrode 25 having a cross shape on the inside and a circular bonding pad 26 are formed on the Au-Zn layer on the p-type contact layer 24 exposed on the surface. It formed by the vapor deposition and lift-off techniques, etc. (refer FIG.1 (b)). Next, the n-side electrode 29 was formed on the opposite side of the main surface of the n-type GaAs substrate 11 by adjusting the substrate thickness to be thin and then depositing AuGe or the like on the entire surface. Through the above manufacturing process, a substantially rectangular parallelepiped semiconductor light emitting device 1 having a side of 250 to 300 μm is formed as shown in FIGS. 1 (a) and 1 (b).

  The semiconductor light emitting device 1 described above has a light emitting region layer 17 composed of an n type cladding layer 14, a light emitting layer 15, and a p type cladding layer 16 on an n type DBR layer 13, and a side portion of the light emitting region layer 17. And a p-type DBR layer 22 having a function of a high-resistance region 20 formed by proton implantation on the n-type DBR layer 13, a light-emitting region layer 17, and a current diffusion layer formed on and in contact with the high-resistance region 20, The RC LED includes a ring-shaped p-side electrode 55 having a cross shape on the inner side on the top surface.

  In the semiconductor light emitting device 1, current is injected from the p-side and n-side electrodes 25 and 29 into the light emitting layer 15, and light having a wavelength of about 665 nm is emitted from the light emitting layer 15. This light is reflected by the upper and lower n-type and p-type DBR layers 13 and 22 as reflection films, resonated, and the emission spectrum width is narrowed to about 5 nm by the photon recycling effect. In the semiconductor light emitting device 1 of FIG. 1, the reflectance of light from the light emitting layer 15 is as high as 99.9% in the lower n-type DBR layer 13, whereas the reflectance in the upper p-type DBR layer 22 is about 95%. And low. Therefore, the resonated light is radiated to the upper p-side electrode 25 side through the upper p-type DBR layer 22 having a low reflectance.

  The semiconductor light emitting device 1 was mounted in a package not sealed with resin and subjected to an operation test and a high temperature and high humidity test. When driven by DC of 10 mA, the light output of the semiconductor light emitting device 1 was 1.5 mW. This is an improvement in light output of about 25% compared to the comparative semiconductor light emitting device 101 packaged under similar conditions. In addition, a continuous current test of 10 mA was performed at a package temperature of 60 ° C. and a humidity of 90%. It was found that the decrease in light output after 1000 hours with respect to the light output at the start of the test was within 0.1 dB. This indicates, for example, that it is sufficiently cleared within 1 dB, which is an example of the required specification under the same conditions, and indicates that the deterioration is suppressed.

  In the high temperature and high humidity test, the reason why the deterioration of the semiconductor light emitting element 1 is suppressed is estimated as follows compared to the conventional example. The high resistance region 20 of the semiconductor light emitting device 1 is located between the upper p-side electrode 25 and the lower n-side electrode 29, particularly at a position about 1 μm away from the p-side electrode 25, and acts to narrow the current path. Have.

  As shown in FIG. 3, when a current is passed between the p-side electrode 25 and the n-side electrode 29, the current 35 is generated by the p-type contact layer 24 and the p-type that have been doped with carbon at a high concentration to reduce the resistance. It passes through the DBR layer 22 and is supplied to the pn junction in the light emitting region layer 17. What prevents the current 35 from the p-side electrode 25 does not exist in the vicinity of the surface of the semiconductor light emitting device 1. That is, conventionally, the semiconductor light emitting device 101 has a high resistance region 120 formed by ion implantation, and is due to oxidation that has occurred starting from a thin line portion on the surface of the p-side electrode 125 in contact with the high resistance region 120. It is presumed that the alteration does not occur in the semiconductor light emitting device 1, and as a result, the light output does not decrease.

  The reason why the light output can be improved as compared with the conventional case is presumed as follows. The semiconductor light emitting device 1 effectively reduces the contact resistance by effectively using the contact surface of the p-side electrode 25 with the p-type contact layer 24, and the p-type contact layer 24 and the p-type DBR layer doped with carbon at a high concentration. This is considered to be a result of the resistance of the 22 being reduced and a relatively large amount of current being supplied to the pn junction relatively uniformly.

  In addition, the semiconductor light emitting element 1 realizes high-speed response. The film thicknesses of the n-type InGaP adjustment layer 18 and the n-type GaAs protective layer 19 are adjusted so that the proton concentration peaks in the n-type cladding layer 14 and the light emitting layer 15. This is because the capacitance of the junction is reduced as a result of efficiently increasing the resistance of the pn junction.

  A semiconductor light emitting device according to Example 2 of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view schematically showing the structure of the semiconductor light emitting device. The difference from Example 1 is that the n-type and p-type DBR layers are thickened and applied to the VCSEL based on the same semiconductor layer structure as in Example 1. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different components will be described.

  As shown in FIG. 4, the semiconductor light emitting device 2 has many of the same components as the semiconductor light emitting device 1 of Example 1, but mainly includes the n-type DBR layer 43, the diameter of the light emitting region layer 17, and the p-type. The DBR layer 52 and the p-side electrode 55 are different.

The n-type DBR layer 43 is AlGaAs-based, that is, a structure in which Al _0.5 Ga _0.5 As and Al _0.95 Ga _0.05 As are alternately stacked, and the number of repetitions is 50 pairs.

  The light emitting region layer 17 is the same as the semiconductor light emitting element 1 except that the diameter is reduced to 10 μm. As a result, the high resistance region 20 surrounds the side portion of the light emitting region layer 17 having a diameter of 10 μm similarly to the semiconductor light emitting element 1.

  The p-type DBR layer 52 is in direct contact with the light-emitting region layer 17 and the high-resistance region 20, has a laminated structure doped with p-type with the same composition as the n-type DBR layer 13, and has 30 pairs of repetitions. The film thickness is about 3 μm.

  The p-side electrode 55 has a ring shape, and the inner diameter of the ring is 9 μm and the width is 5 μm. The p-side electrode 55 is connected to a bonding pad (not shown) arranged close to the p-side electrode 55. The ring-shaped p-side electrode 55 overlaps the boundary between the circular light emitting region layer 17 and the high resistance region 20 so that the centers are substantially coincided with each other when viewed from above.

  The manufacturing method of the semiconductor light emitting device 2 is substantially the same as that of the semiconductor light emitting device 1 of the first embodiment. However, the n-type and p-type DBR layers 43 and 52 are thickly grown. Although the p-type DBR layer 52 is as thick as about 3 μm, the high-resistance region 20 can be formed by proton implantation before the p-type DBR layer 52 is grown. unnecessary. Moreover, since the diameter of the light emitting region layer 17 is as small as 10 μm and the corresponding p-side electrode 55 is also small, it is formed by changing the mask pattern used. As a result, a substantially rectangular parallelepiped semiconductor light emitting element 2 having one side of 250 to 300 μm is formed.

  The semiconductor light emitting device 2 described above has a light emitting region layer 17 composed of an n type cladding layer 14, a light emitting layer 15, and a p type cladding layer 16 on an n type DBR layer 43, and a side portion of the light emitting region layer 17. A p-type DBR layer 52 having a function of a high-resistance region 20 formed by proton implantation on the n-type DBR layer 43, a light-emitting region layer 17 and a current diffusion layer formed on and in contact with the high-resistance region 20; The VCSEL includes a ring-shaped p-side electrode 55 on the uppermost surface.

  In the semiconductor light emitting device 2, current is injected from the p-side and n-side electrodes 55 and 29 into the light emitting layer 15, and light having a wavelength of 665 nm is emitted from the light emitting layer 15. This light is reflected by the upper and lower n-type and p-type DBR layers 43 and 52 serving as a reflective film, resonated, and stimulated emission occurs to become laser light. In the semiconductor light emitting device 2, the reflectance with respect to the light from the light emitting layer 15 is as high as 99.95% in the lower n-type DBR layer 43, whereas the reflectance of the upper p-type DBR layer 52 is approximately 99%. Low. Therefore, the resonated light is radiated to the upper p-side electrode 55 side through the upper p-type DBR layer 52 having a low reflectance.

  In the operation test of the semiconductor light emitting device 2, the oscillation threshold current was about 2.5 mA, the maximum oscillation temperature was 60 ° C., and good characteristics were obtained as the LD of this wavelength band. The semiconductor light emitting device 2 that is a VCSEL cannot be compared with the semiconductor light emitting device 1 of Example 1 that is an RC type LED. Therefore, a VCSEL having a semiconductor layer structure substantially similar to that of the conventional semiconductor light emitting element 101 and having a light emitting region layer diameter of 10 μm was manufactured and compared. As a result, in the semiconductor light emitting device 2 of this example, the fluctuation of the threshold value was small even after 2000-hour energization oscillation, and no abnormality was observed in the near-field image. On the surface of the semiconductor light emitting device 2, no oxidation is observed starting from the thin line portion of the p-side electrode 55, and no deterioration occurs. On the other hand, in the conventional semiconductor light emitting device 101, discoloration was observed on the surface in 1000 hours, and an element that was not able to oscillate was generated.

  Further, the semiconductor light emitting device 2 has good characteristics because it is not easily affected by damage during proton implantation. That is, when the high resistance region 20 is manufactured, the acceleration energy for injecting protons is as small as about 150 keV, and the damage is suppressed to a small level. On the other hand, in a VCSEL having a semiconductor layer structure substantially similar to that of the conventional semiconductor light emitting device 101, when a high resistance region is produced, protons are injected through the already grown p-type DBR layer. Therefore, there is a possibility that the damage due to the proton injection deteriorates the oscillation characteristics.

  In addition, the semiconductor light emitting device 2 by proton implantation has a small influence of crystal anisotropy even when an inclined substrate is used for polarization control. That is, in the so-called selective oxidation type VCSEL, when a tilted substrate is used for polarization control, anisotropy occurs in selective oxidation, and another problem arises that the influence of anisotropy must be considered. In the semiconductor light emitting element 2, since the problem of anisotropy is suppressed, a complicated process is not required.

  Further, the slope efficiency of the semiconductor light emitting element 2 is improved as compared with the conventional semiconductor light emitting element 101. The light output is improved. Similar to the semiconductor light emitting device 1, the contact surface of the p-side electrode 55 with the p-type contact layer 24 is effectively used to reduce contact resistance, and the p-type contact layer 24 and p-type doped with carbon at a high concentration. The resistance of the DBR layer 52 is reduced, and a relatively large amount of current is considered to be a result of being supplied to the pn junction relatively uniformly.

  In the semiconductor light emitting device 2, the pn junction portion is efficiently increased in resistance, so that the junction capacitance is reduced and high-speed response is realized.

  A semiconductor light-emitting device according to Example 3 of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view schematically showing the structure of the semiconductor light emitting device. The p-type DBR layer is different from the first embodiment. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different components will be described.

  As shown in FIG. 5, the semiconductor light emitting device 3 has the same components as the semiconductor light emitting device 1 of Example 1, but mainly includes a p-type DBR layer 62, a p-type current diffusion layer 63, and a p-type current diffusion layer 63. The side electrodes 65 are different.

The p-type DBR layer 62 has a structure in which six pairs of Al _0.5 Ga _0.5 As and Al _0.95 Ga _0.05 As are alternately stacked on the light emitting region layer 17 in the first crystal growth. Is formed. After the growth, proton implantation is performed from above the p-type DBR layer 62 through the adjustment layer, the protective layer (not shown), and the like, and the side portion of the p-type DBR layer 62 is also incorporated into the high resistance region 20. Yes. A columnar region surrounded by the high resistance region 20 and not injected with protons is an upper portion of the p-type DBR layer 62, the light emitting region layer 17, and the n-type DBR layer 13 from above.

The p-type current diffusion layer 63 is formed on the p-type DBR layer 62 and the high resistance region 20 by the second crystal growth. It is a monolayer of about 0.6 μm thick made of p-type Al _0.7 Ga _0.3 As doped with carbon at a concentration of 2 to 4 × 10 ¹⁸ cm ⁻³ .

  The p-side electrode 65 is formed on the p-type contact layer 24 on the p-type current diffusion layer 63 in a ring shape having an inner diameter of 110 μm and a width of 5 μm. The p-side electrode 65 is connected to a bonding pad (not shown) arranged close to the p-side electrode 65. The ring-shaped p-side electrode 65 has a ring inner diameter arranged on the outer side with the center substantially coincided with the circular boundary between the p-type DBR layer 62 and the high resistance region 20 when viewed from above. The material of the p-side electrode 65 is the same as that of the p-side electrode 25 of the semiconductor light emitting device 1.

  In part of the method for manufacturing the semiconductor light emitting device 3, as described above, the p-type DBR layer 62 is formed by the first crystal growth. At the time of proton injection, the thickness of the n-type InGaP adjustment layer (not shown) is about 0.1 μm so that the position of the light emitting region layer 17 from the surface of the pn junction is substantially the same as in Example 1. So thin. Thereafter, proton implantation is performed under substantially the same conditions as in Example 1.

  In the second crystal growth, the p-type current diffusion layer 63 is grown on the p-type DBR layer 62 and the high resistance region 20. Moreover, since the diameter of the p-side electrode 65 is increased, the p-side electrode 65 is formed by changing the mask pattern to be used. Other manufacturing methods are almost the same as the manufacturing method of the semiconductor light emitting device 1 of the first embodiment. As a result, a substantially rectangular semiconductor light emitting element 3 having a side of 250 to 300 μm is formed.

  The semiconductor light emitting element 3 described above has a p-type DBR layer 62 on the light emitting region layer 17, and protons are injected into the side portions of the light emitting region layer 17 and the p type DBR layer 62 and on the n type DBR layer 13. RC type LED including a high resistance region 20 formed by the above, a p type DBR layer 62 and a p type current diffusion layer 63 formed on and in contact with the high resistance region 20, and a ring-shaped p-side electrode 65 on the uppermost surface. is there.

  This semiconductor light emitting device 3 was subjected to an operation test and a high temperature and high humidity test in the same manner as the semiconductor light emitting device 1 of Example 1. In the semiconductor light emitting device 3, the reflectance with respect to the light from the light emitting layer 15 is as high as 99.9% for the lower n-type DBR layer 13, and as low as about 90% for the upper p-type DBR layer 62. Therefore, the resonated light is radiated to the upper p-side electrode 65 side through the upper p-type DBR layer 62 having a low reflectance.

  When driven by DC of 10 mA, the light output of the semiconductor light emitting device 3 is improved by about 5 to 10% as compared with the semiconductor light emitting device 1. Further, in a continuous current test of 10 mA at a package temperature of 60 ° C. and a humidity of 90%, the same result as that of the semiconductor light emitting device 1 is obtained. Since the number of repetitions of the upper p-type DBR layer 62 is smaller than that of the semiconductor light emitting device 1, the resonance effect is reduced, but the p-type current diffusion layer 63 for current diffusion is formed on the p-type DBR layer 62. As a result of the formation, the effect of current diffusion is increased. As a result, a more uniform current is supplied from the ring-shaped p-side electrode 65 to the pn junction portion of the light emitting region layer 17 and the emitted light is extracted by the ring-shaped p-side electrode 65 having an enlarged inner diameter. The light output is improved by reducing the ratio of obstruction.

  In addition, the same effects as those of the semiconductor light emitting device 1 of Example 1 are obtained.

  A semiconductor light-emitting device according to Example 4 of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view schematically showing the structure of the semiconductor light emitting device. The difference from Example 1 is that the n-type and p-type DBR layers are replaced with n-type and p-type current spreading layers. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different components will be described.

  As shown in FIG. 6, the semiconductor light emitting device 4 has many of the same components as the semiconductor light emitting device 1 of Example 1, but mainly differs in the n-type current diffusion layer 73 and the p-type current diffusion layer 82. ing.

The n-type current diffusion layer 73 is formed on the n-type buffer layer 12 with an n-type impurity such as n-type Al _0.7 Ga _0.3 As doped with silicon at a high concentration. A single layer of 4 μm.

The p-type current diffusion layer 82 is formed on the light emitting region layer 17 and the high resistance region 20 by the second crystal growth. It is a single layer having a thickness of about 1 μm made of p-type Al _0.7 Ga _0.3 As doped with carbon at a concentration of 2 to 4 × 10 ¹⁸ cm ⁻³ .

  In the method for manufacturing the semiconductor light emitting device 4, the n-type current diffusion layer 73 is formed by the first crystal growth, and the p-type current diffusion layer 82 is formed by the second crystal growth. The n-type and p-type DBR layers of Example 1 are replaced, and these single layers are crystal-grown, respectively.

  The semiconductor light-emitting element 4 described above has an n-type current diffusion layer 73 on the n-type buffer layer 12, and is formed by proton injection on the side of the light-emitting region layer 17 and on the top of the n-type current diffusion layer 73. A p-type current diffusion layer 82 formed on and in contact with the high-resistance region 20, the light-emitting region layer 17 and the high-resistance region 20, and a ring-shaped p-side electrode 25 with a cross-shaped thin wire connected to the innermost surface on the top surface. It is LED provided.

  This semiconductor light emitting device 4 was subjected to an operation test and a high temperature and high humidity test in the same manner as the semiconductor light emitting device 1 of Example 1. Since the semiconductor light emitting device 4 does not include the n-type and p-type DBR layers, intentional reflection does not occur as in the semiconductor light emitting device 1, and the emitted light is emitted from the upper side along the cylinder of the light emitting region layer 17. Strongly radiated and simultaneously radiated from the side.

  When driven by DC of 10 mA, the light output of the semiconductor light emitting device 4 was improved by about 10% compared to the semiconductor light emitting device 1. Further, in a 10 mA continuous energization test at a package temperature of 60 ° C. and a humidity of 90%, the same result as that of the semiconductor light emitting device 1 was obtained. Compared with the semiconductor light emitting element 1, the effect of current diffusion is increased by forming the p-type current diffusion layer 82 in contact with the upper side of the light emitting region layer 17. As a result, the light output is improved by supplying a more uniform current from the ring-shaped p-side electrode 25 having the cruciform thin line connected to the inside to the pn junction of the light emitting region layer 17. . However, since there is no photon recycling effect due to the elimination of the resonant structure, the output improvement is only about 10%.

  It is known that a thicker p-type current diffusion layer 82 between the light emitting region layer 17 and the p-side electrode 25 supplies a more uniform current to the pn junction. It has been found that when the thickness of the type current diffusion layer 82 exceeds about 5 μm, the current path becomes longer, the resistance increases, the drive voltage increases, and high-speed operation becomes difficult. On the contrary, when the p-type current diffusion layer 83 becomes thin, the resistance decreases, but it becomes difficult to supply a uniform current to the pn junction, and the light output decreases below about 0.5 μm. It was.

  Further, the semiconductor light emitting device 4 does not require the n-type and p-type DBR layers as compared with the semiconductor light emitting device 1 of Example 1, so that the structure is simple and the production yield is increased. As a result of the formation of the high resistance region 20 so that the proton concentration peaks in the n-type cladding layer 14 and the light emitting layer 15, the junction capacity is reduced, so that high-speed response of about 250 Mbps is realized. Has been. Although the transmission speed is lower than that of the semiconductor light emitting device 1 of Example 1, it is applicable to low-cost applications. In addition, the same effects as those of the semiconductor light emitting device 1 of Example 1 are obtained.

  Next, a modification of the fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view schematically showing the structure of the semiconductor light emitting device. The difference from Example 4 is that the n-type GaAs substrate is replaced with an n-type GaP substrate. Hereinafter, the same components as those in the fourth embodiment are denoted by the same reference numerals, description thereof will be omitted, and different components will be described.

  As shown in FIG. 7, the semiconductor light emitting device 5 has the same components as the semiconductor light emitting device 4 described above, but mainly differs in the n-type GaP substrate 71 and the adhesive layer 72.

  The n-type GaP substrate 71 is disposed at a position where the n-type GaAs substrate is replaced, and is bonded to the n-type current diffusion layer 73 via the adhesive layer 72.

  The manufacturing method of the semiconductor light emitting device 3 is greatly different from that of the semiconductor light emitting device 4 of the fourth embodiment. Although illustration is omitted, in the first crystal growth, the buffer layer, the n-type InGaP adjustment layer, the p-type cladding layer 16, the light emitting layer 15, and the n-type GaAs substrate are formed on the n-type GaAs substrate in the reverse direction. The mold cladding layer 14, the n-type current diffusion layer 73, and the n-type adhesive layer 72 are grown sequentially. Next, the n-type GaP substrate 71 is bonded to the n-type adhesive layer 72 by high-temperature processing. Next, the n-type GaAs substrate and the buffer layer are etched away, and the n-type InGaP adjustment layer is exposed. Thereafter, similarly to the semiconductor light emitting element 4, after the ion implantation of protons from above the n-type InGaP adjustment layer and the removal of the n-type InGaP adjustment layer, the second crystal growth is performed. A protective layer for protecting the surface, an etching stop layer, and the like are omitted.

  The semiconductor light-emitting element 5 described above has an n-type current diffusion layer 73 on an n-type GaP substrate 71 via an n-type adhesive layer 72, and has a side portion of the light emitting region layer 17 and an upper portion of the n-type current diffusion layer 73. A high resistance region 20 formed by proton implantation, a p-type current diffusion layer 82 formed on and in contact with the light emitting region layer 17 and the high resistance region 20, and a ring having a cross-shaped thin line connected to the inside on the top surface. It is LED provided with the shape p-side electrode 25. FIG.

  This semiconductor light emitting device 5 was subjected to an operation test and a high temperature and high humidity test in the same manner as the semiconductor light emitting device 4 of Example 4. The semiconductor light emitting element 5 has the same effect as the semiconductor light emitting element 4. In addition, since the n-type GaP substrate 71 transparent to the emission wavelength is provided, the emitted light is not only from the upper side along the cylindrical shape of the light emitting region layer 17 but also from the side surface of the lower n-type GaP substrate 71. And the light output is about 1.5 times that of the semiconductor light emitting device 4 of Example 4.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the embodiment, the semiconductor light emitting device has an n type semiconductor layer, a light emitting layer, and then a p type semiconductor layer formed on an n type GaAs substrate or an n type GaP substrate. A p-type semiconductor layer, an active layer, and then an n-type semiconductor layer may be formed on the p-type GaAs substrate or the p-type GaP substrate.

  Further, in the embodiment, an example of a red RC LED, a VCSEL, and a normal LED having an emission wavelength of about 665 nm has been described. However, a similar semiconductor light emitting element that emits light at other wavelengths, for example, near infrared, or It is possible to apply to a similar semiconductor light emitting element that emits light with a shorter wavelength than red.

  In the embodiment, an example in which carbon is auto-doped in the p-type DBR layer, the p-type current diffusion layer, the p-type contact layer, etc. has been described. However, carbon may be supplied from other semiconductor material gas, It is also possible to use other impurities, such as zinc.

In the example, the n-type DBR layer on the lower side of the RC type LED and the VCSEL has a repetition number of 40 to 50 in which Al _0.5 Ga _0.5 As and Al _0.95 Ga _0.05 As are alternately laminated. Although an example in which a pair is formed is shown, if the reflectance is 99.9% or more, it can be replaced with another reflective film.

The present invention can be configured as described in the following supplementary notes.
(Additional remark 1) The light emitting area | region which has the 1st reflective film which reflects the light of a fixed wavelength, the light emitting layer which radiates | emits the light of the said wavelength formed on the said 1st reflective film, and the said light emitting area | region A high resistance region formed by ion implantation on the side of the layer, and the implanted element in contact with the light emitting region layer and the high resistance region and diffused in the vicinity of the interface with the high resistance region; A second reflective film that reflects the light of the wavelength; a first electrode formed on the second reflective film and above the light emitting region layer through a contact layer; A semiconductor light emitting device comprising: a second electrode formed below the first reflective film on the side opposite to the electrode.

(Supplementary note 2) The semiconductor light-emitting device according to supplementary note 1, wherein the layer between the light emitting region layer and the first electrode has a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ or more and 2 × 10 ¹⁹ cm ⁻³ or less. element.

(Supplementary note 3) The semiconductor light-emitting element according to supplementary note 1, wherein the wavelength is 665 nm.

(Supplementary note 4) The semiconductor light emitting element according to supplementary note 1, wherein the layer between the high resistance region and the first electrode is at least one of p-type GaAs and AlGaAs whose dopant is carbon.

(Supplementary note 5) The semiconductor light emitting element according to supplementary note 1, wherein the first electrode has a ring shape.

(Supplementary note 6) The semiconductor light emitting element according to supplementary note 4, wherein a center of the light emitting region layer and a center of the ring-shaped first electrode substantially coincide with each other when viewed from a direction perpendicular to the light emitting region layer.

(Additional remark 7) The said 1st electrode is a semiconductor light-emitting device of Additional remark 5 by which the cross-shaped electrode is further connected inside the said ring.

(Additional remark 8) The said 2nd reflective film is a semiconductor light-emitting element of Additional remark 1 whose repetition number of a reflective film with a high refractive index and a reflective film with a low refractive index is 5 pairs or more and 50 pairs or less.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the structure of the semiconductor light-emitting device based on Example 1 of this invention, FIG.1 (a) is front sectional drawing, FIG.1 (b) is the top view which looked at the semiconductor light-emitting device from the upper direction. Sectional drawing which shows typically the manufacturing process of the semiconductor light-emitting device based on Example 1 of this invention in order of a process. The figure which shows typically the flow of the injection current of the semiconductor light-emitting device concerning Example 1 of this invention. Sectional drawing which shows typically the structure of the semiconductor light-emitting device based on Example 2 of this invention. Sectional drawing which shows typically the structure of the semiconductor light-emitting device based on Example 3 of this invention. Sectional drawing which shows typically the structure of the semiconductor light-emitting device based on Example 4 of this invention. Sectional drawing which shows typically the structure of the semiconductor light-emitting device concerning the modification of Example 4 of this invention. Sectional drawing which shows the structure of the conventional semiconductor light-emitting device typically.

Explanation of symbols

1, 2, 3, 4, 5, 101 Semiconductor light emitting device 11, 111 n-type GaAs substrate 12, 112 buffer layers 13, 43, 113 n-type DBR layers 14, 114 n-type cladding layers 15, 115 Light-emitting layers 16, 116 p-type cladding layer 17, 117 light emitting region layer 18 n-type InGaP adjustment layer 19 n-type GaAs protective layer 20, 120 high-resistance regions 22, 52, 62, 112 p-type DBR layers 24, 124 p-type contact layers 25, 55, 65, 125 p-side electrode 26 bonding pad 29, 129 n-side electrode 31 mask layer 35 current 63, 82 p-type current diffusion layer 71 n-type GaP substrate 72 n-type adhesive layer 73 n-type current diffusion layer

Claims (5)

A first reflective film that reflects light of a certain wavelength;
A light emitting region layer having a light emitting layer that emits light of the wavelength formed on the first reflective film;
A high resistance region formed by ion implantation on the side of the light emitting region layer;
A second reflective film that is in contact with the light emitting region layer and the high resistance region and has the implanted element diffused in the vicinity of the interface with the high resistance region, and reflects light of the wavelength;
A first electrode formed on the second reflective film and above the light emitting region layer via a contact layer;
A second electrode formed below the first reflective film on the opposite side of the first electrode;
A semiconductor light emitting device comprising: A first reflective film that reflects light of a certain wavelength;
A light emitting region layer having a light emitting layer that emits light of the wavelength formed on the first reflective film;
A second reflective film that is in contact with the light emitting region layer and reflects light of the wavelength;
A high resistance region formed by ion implantation on the side of the light emitting region layer and the second reflective film;
A current diffusion layer having the implanted element in contact with the second reflective film and the high resistance region and diffused in the vicinity of the interface with the high resistance region;
A first electrode formed on the current diffusion layer and above the light emitting region layer via a contact layer;
A second electrode formed below the first reflective film on the opposite side of the first electrode;
A semiconductor light emitting device comprising: A first current spreading layer;
A light emitting region layer having a light emitting layer that emits light of a certain wavelength formed on the first current spreading layer;
A high resistance region formed by ion implantation on the side of the light emitting region layer;
A second current diffusion layer having the implanted element in contact with the light emitting region layer and the high resistance region and diffused in the vicinity of the interface with the high resistance region;
A first electrode formed on the second current spreading layer and above the light emitting region layer via a contact layer;
A second electrode formed below the first current diffusion layer on the opposite side of the first electrode;
A semiconductor light emitting device comprising:   4. The semiconductor light emitting device according to claim 1, wherein the implanted ions are protons.   5. The semiconductor light-emitting element according to claim 1, wherein a layer between the light-emitting region layer and the first electrode has a thickness of 0.5 μm to 5 μm. .

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