JP2007329468A - Light-emitting element, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicon light emitting element, along with its manufacturing method, which has a high emission intensity and is suitable as the current injection type. <P>SOLUTION: A light emitting element 30 has such structure as a p-type transparent conductive film 51 and an n-type transparent conductive film 52 are provided on both sides of a light emitting layer 12 containing silicon oxide (SiO<SB>x</SB>, 0.5<x<1.5) and erbium (Er). The emission intensity especially near the wavelength 1.5 μm increases as erbium atoms are optically acitivated. The p-type transparent conductive film 51 and the n-type transparent conductive film 52 are made from such material as a band gap is larger than the light emitting layer 12, for improved quantum efficiency, reduced operation voltage, and longer life, resulting in actualizing of a current injection type silicon light emitting element. So mounting of a light emitting element in an integrated circuit is easier. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting element capable of suitably emitting light in a communication wavelength band, for example, and a method for manufacturing the same.

  Currently, the operating frequency of a semiconductor integrated circuit (hereinafter simply referred to as an integrated circuit) reaches 3 GHz, and wiring in the integrated circuit requires complicated handling as a distributed constant circuit, and electromagnetic interference between wirings can be ignored. It is gone. Therefore, in order to solve these problems, it has been proposed to perform signal transmission in an integrated circuit using an optical signal. Furthermore, in order to realize this at a low cost, some elements have been prototyped with the aim of building a system with each optical device (light emission, light reception, modulation, waveguide, etc.) based on silicon (Si) materials. Yes. Among these, development of a light emitting element is particularly urgent. The reason is that silicon is indirect transition type and hardly emits light, and most of the light emitting material is a direct transition type III-V group semiconductor such as gallium arsenide (GaAs). Under such circumstances, for example, Si / SiGe materials, iron silicide, erbium-doped silicon, and the like have been developed as silicon-based light emitting materials for near-infrared light emission, but the light emission intensity is higher than that of III-V semiconductors. There was a problem that was several orders of magnitude lower. There is also a problem that it is difficult to form a light-emitting element using a III-V group semiconductor on a silicon substrate.

On the other hand, a “fiber amplifier” composed of a material in which erbium (Er) is added to silicon dioxide (SiO ₂ ) has already been developed and is practically used as an element that amplifies light in the communication wavelength band of 1.5 μm by laser excitation. It has become. By using a silicon-based light emitting material used for such a fiber amplifier or the like, a light emitting element can be formed on a silicon substrate together with an integrated circuit, and the element structure can be simplified. In addition to this, an optical amplifier using an erbium-doped Si nanocrystal formed on a silicon substrate (Non-patent Document 1), or a current injection type light-emitting element using erbium-doped SiO ₂ formed on a silicon substrate (Non-patent Document 2). ) Has also been developed.
Etch. -S. Han et al., “Applied Physics Letters”, vol. 79, 2001, p. 4568 Maria Eloisa Castagna, Salvatore Coffa, Mariatonnietta Monaco, Liliana Caristia, Alberto Messina, Rosa Rio Mangano Bongiorno), “Physica E”, vol. 16, 2003, p. 547-553

  However, the light emission intensity of the light-emitting element formed using the above-described silicon-based light-emitting material is still inferior to that of a III-V group semiconductor, and there is a problem that a large driving voltage of about several tens of volts is required for current injection. Therefore, a light-emitting element that has a high emission intensity especially in the vicinity of a wavelength band of 1.5 μm for communication and that allows easy current injection has been desired.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a silicon-based light-emitting element that has a high light emission intensity, particularly in the 1.5 μm band, and that allows easy current injection, and a method for manufacturing the same. It is in.

The light-emitting element of the present invention includes a light-emitting layer containing silicon oxide (SiO _x , 0.5 <x <1.5) and erbium (Er).

In the light-emitting element of the present invention, the light-emitting layer is configured to include silicon oxide (SiO _x , 0.5 <x <1.5) and erbium (Er), so that erbium atoms are separated from surrounding oxygen atoms. Since it binds and ionizes (Er ³⁺ ) and is optically activated, the emission intensity increases particularly in the wavelength band of 1.5 μm.

  In the light emitting device of the present invention, a pair of clad layers having a refractive index lower than that of the light emitting layer may be provided on both sides of the light emitting layer. Thereby, efficient light confinement becomes possible.

  As a pair of clad layers, for example, there are a first transparent conductive film (n-type) and a photonic crystal layer (p-type), or a first transparent conductive film (n-type) and a second transparent conductive film (p-type). There is.

Examples of the first transparent conductive film include tin dioxide (SnO ₂ ), indium tin oxide (ITO), indium oxide (In ₂ O ₃ ), and zinc oxide (ZnO). As the second transparent conductive film, zinc oxide (ZnO), tin dioxide (SnO ₂ ), nickel oxide (NiO), copper oxide (Cu ₂ O), iron oxide (FeO), bismuth oxide (Bi ₂ O _3). ), Praseodymium oxide (Pr ₂ O ₃ ), thallium oxide (Tl ₂ O ₃ ), delafossite (CuAlO ₂ ) and strontium copper oxide (SrCu ₂ O ₂ ). These materials have a refractive index lower than that of the light emitting layer and a larger band gap than that of the light emitting layer. Therefore, in addition to optical confinement, it is possible to confine carriers (electrons and holes), and the operating voltage is greatly increased. To reduce.

  Another light-emitting element of the present invention includes a light-emitting layer containing silicon (Si), oxygen (O), and erbium (Er) and having an optical band gap of 1.1 or more and 4.0 or less. . Thereby, the barrier of carriers to the light emitting layer at the time of current injection is lowered, and efficient carrier confinement becomes possible.

  In the method for manufacturing a light-emitting element of the present invention, silicon monoxide (SiO) and erbium are simultaneously deposited on a substrate by resistance heating vapor deposition or sputtering, and a thin film is formed. The light emitting layer is formed by performing heat treatment at the following temperature.

According to the light emitting device and the method of manufacturing the same of the present invention, the light emitting layer is configured to contain silicon oxide (SiO _x , 0.5 <x <1.5) and erbium, The light emission intensity in the communication wavelength band near 5 μm can be improved. According to another light emitting device of the present invention, the light emitting layer contains silicon, oxygen, and erbium, and the optical band gap is 1.1 or more and 4.0 or less. Injection is easy. As a result, the light emitting element can be formed on the silicon substrate together with the integrated circuit, so that the cost and size can be reduced. Furthermore, since the dielectric breakdown is less likely to occur in the light emitting layer as compared with conventional silicon-based materials (for example, silicon dioxide to which erbium is added), the device life is significantly extended.

  In addition, if a pair of transparent conductive films having a band gap larger than that of the light emitting layer is provided on both sides of the light emitting layer, efficient carrier confinement becomes possible, so that quantum efficiency is improved and operating voltage is greatly increased. To reduce. As a result, it is possible to realize a current injection type silicon-based light emitting element that does not involve photoexcitation. Normally, the pump light is different from the optical signal of the integrated circuit, so if it can be driven only by current injection without using the pump light at all, miniaturization is realized and the light emitting element is mounted in the integrated circuit. Becomes easy.

  Furthermore, in the future, when an optical fiber is connected to each home (FTTH; Fiber To The Home), it is necessary to connect the optical fiber to a computer. At that time, an integrated circuit including the above-described light emitting element in the computer. By providing the above, it is possible to improve not only the signal transmission inside the integrated circuit but also the signal communication performance between the external communication network and the computer. Furthermore, by incorporating the light-emitting element into a signal processing device such as a router serving as a branch point of the optical fiber, the cost and power consumption of the device can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 shows a light emitting device 10 according to a first embodiment of the present invention. The light emitting element 10 includes a light emitting layer 12 on a substrate 11 and generates fluorescence (PL: Photo Luminescence) by irradiation with excitation light or current injection. In the PL spectrum, the light emitting element has a peak wavelength observed near 1,53 μm with respect to excitation light having a wavelength of 633 nm.

The substrate 11 is made of, for example, silicon (Si) and has a thickness of, for example, 300 μm. The light emitting layer 12 includes silicon oxide (SiO _x , 0.5 <x <1.5, hereinafter referred to as SiO _x ) and erbium (Er), and has a thickness of, for example, 1.5 μm. SiO _x has an intermediate composition between silicon (Si) and silicon dioxide (SiO ₂ ) and has a uniform composition. The composition of the SiO _x is 0.5 <x <1.5. Further, preferably 0.8 <x <1.4. Further, the optical band gap of SiO _x is 1 to 4 eV, preferably 1.5 to 3 eV, which is smaller than the band gap of silicon dioxide (about 8 to 9 eV).

  Here, the content of erbium in the light emitting layer 12 is preferably 0.5 atomic% (atomic%) or more and 10 atomic% or less, and more preferably 1 atomic% or more and 7 atomic% or less. The erbium content (atomic%) is the ratio of the atomic density to the entire light emitting layer 12 (the total of the constituent materials of the light emitting layer 12), for example, X-ray photoelectron spectroscopy (XPS). Can be measured.

  This light emitting layer 12 can be manufactured as follows, for example.

First, as shown in FIG. 2A, silicon monoxide and erbium are simultaneously deposited on the substrate 11 to form a thin film 12A having a thickness of 1.5 μm, for example. At this time, the degree of vacuum is set to 1 × 10 ⁻¹ Pa to ¹ × 10 ⁻⁶ Pa, for example, and erbium and silicon monoxide are deposited on the substrate 11 by vapor deposition using, for example, a resistance heating method or a sputtering method. .

Moreover, as an atmospheric gas at the time of vapor deposition, for example, an oxygen-containing gas of 1 × 10 Pa to 1 × 10 ⁻⁴ Pa, a silicon-containing gas, or the like may be used. By using an oxygen-containing gas, it is possible to approximate the composition of the SiO _x to SiO ₂ (x = _2), by using a silicon-containing gas, it is possible to make the composition of the SiO _x to Si (x = 0) . Therefore, it is possible to adjust the composition ratio of silicon and oxygen in the formed thin film 12A by performing deposition while adjusting the respective flow rates using both the oxygen-containing gas and the silicon-containing gas. Examples of the silicon-containing gas include silane (SiH ₄ ) and theos (Si (OC ₂ H ₅ ) ₄ ). Furthermore, the substrate temperature at the time of vapor deposition can be, for example, 20 ° C. or higher and 800 ° C. or lower.

Next, as shown in FIG. 2B, the thin film 12A formed on the substrate 11 is heat-treated in an oxygen-containing atmosphere of, for example, about 1 to 0.1 atm. Thereby, the thin film 12A is oxidized to form the light emitting layer 12 containing SiO _x and erbium, and the light emitting element 10 is completed. The temperature of the heat treatment is, for example, 350 ° C. to 850 ° C., preferably 350 ° C. or more and 650 ° C. or less, more preferably 550 ° C., from the viewpoint of optical activation due to ionization (Er ³⁺ ) of erbium atoms. . When the heat treatment temperature is lower than 350 ° C., the ionization is not promoted so much. Conversely, when the heat treatment temperature is higher than 850 ° C., SiO _x is separated into silicon and silicon dioxide, and erbium ions are taken into silicon and become non-ionized. This is for optical inactivation. Note that the atmosphere gas for performing the heat treatment is not limited to the oxygen-containing atmosphere, and pure oxygen, pure nitrogen, dry air, or the like can also be used.

In the light-emitting element 10 of the present embodiment, the light-emitting layer 12 includes silicon oxide (SiO _x , 0.5 <x <1.5) and erbium, so that erbium atoms are oxygen atoms in the vicinity. And is ionized (Er ³⁺ ) and optically activated. At this time, if x is smaller than 0.5, the oxygen content becomes insufficient, and most of the erbium atoms cannot be bonded to oxygen and are not optically activated, which is not preferable. On the other hand, when x is larger than 1.5, the composition of SiO _x becomes close to SiO ₂ and the band gap increases, which is not preferable.

When carriers (electrons, holes) are generated or injected into the conductor and valence band of SiO _{x as} a base material by photoexcitation or current injection, energy is generated by recombination of electron-hole pairs. As a result, electrons in the erbium ions are excited (Auger effect), and when the electrons relax energy, light emission particularly in the vicinity of 1.5 μm, which is a communication wavelength band, is generated. At this time, since the energy state of SiO _x is not localized, dielectric breakdown is unlikely to occur, and the device life is significantly extended.

  Furthermore, when the erbium content is 0.5 atomic% or more and 10 atomic% or less, the emission intensity in the vicinity of a wavelength of 1.5 μm can be effectively increased. In addition, since the optical band gap of the light emitting layer 12 is as low as 1 to 4 eV, efficient carrier confinement in the light emitting layer 12 is possible, and thus a current injection type light emitting device with a drastically reduced driving voltage can be manufactured. It becomes.

In the method for manufacturing the light emitting layer 12, the heat treatment temperature is set to 350 ° C. or higher and 850 ° C. or lower, particularly 350 ° C. or higher and 650 ° C. or lower, whereby the absorption coefficient in SiO _x is increased and ionization of erbium atoms by oxidation is promoted. Therefore, the emission intensity in the communication wavelength band is improved. As a result, the light emitting element can be formed on the silicon substrate together with the integrated circuit, which leads to cost reduction and simplification of the manufacturing process.

[Second Embodiment]
FIG. 3A is a diagram illustrating a cross-sectional configuration of a light-emitting element 20 according to the second embodiment of the present invention. The light emitting element 20 is configured by sequentially stacking a p-type current injection layer 21, a ZnO light emitting layer 22, and an n-type current injection layer 23 on the light emitting layer 12 of the light emitting element 10. In the light emitting element 20, as shown in FIG. 3B, when a voltage is applied between the n-type current injection layer 23 and the p-type current injection layer 21, electrons and holes are regenerated in the ZnO light-emitting layer 22. Combined to emit ultraviolet light (wavelength 200 nm to 400 nm) or visible light (wavelength 400 nm to 800 nm) on the light emitting layer 12 side. By irradiating the light emitting layer 12 with the ultraviolet light or visible light, this becomes excitation light to excite erbium in the light emitting layer 12 to generate fluorescence. Note that, instead of the ZnO light emitting layer 14, a light emitting layer that generates visible light such as an organic material may be used.

  Further, as shown in FIG. 4, the p-type current injection layer 21 and the n-type current injection layer 23 do not necessarily have to be provided. For example, the p-type ZnO layer 22p and the n-type are formed on the light emitting layer 12. The ZnO layer 22n may be stacked.

[Third Embodiment]
FIG. 5A is a diagram illustrating a cross-sectional configuration of a light-emitting element 30 according to the third embodiment of the present invention. In the light emitting element 30, an n-type silicon layer 31 and a p-type silicon layer 32 are provided above and below the light emitting element 12 of the light emitting element 10. Further, the left and right end faces of the light emitting layer 12 have a resonant structure in which the reflectivity is set appropriately, whereby laser oscillation is performed.

In the light emitting element 30, since the light emitting layer 12 is composed of SiO _x and erbium, when a voltage is applied between the n-type silicon layer 31 and the p-type silicon layer 32, electrons and holes are generated in the light emitting layer 12. Recombination occurs, and infrared light is emitted by electrons in the erbium ions excited by the recombination. This light is reflected by the left and right end faces of the light emitting layer 12, causes laser oscillation at a wavelength at which the phase change when reciprocating once is an integral multiple of 2π, and is emitted as a beam to the outside. At this time, since the optical band gap of the light emitting layer 12 is as narrow as 1 to 4 eV, as shown in FIG. 5B, in the carrier injection from the n-type silicon layer 31 and the P-type silicon layer 32 to the light emitting layer 12. The barrier is lowered. Accordingly, even when the light emitting layer 12 is sandwiched between layers having a narrow band gap such as conventional silicon, the operating voltage can be reduced.

[Fourth Embodiment]
FIG. 6 illustrates a cross-sectional structure of a light emitting device 40 manufactured by providing a light confinement structure (laser structure) in the light emitting device 10 according to the first embodiment.

  In the light emitting element 40, an n-type transparent conductive film 41 and a p-type photonic crystal layer 42 as a pair of cladding layers are provided above and below the light emitting layer 12 in the light emitting element 10. Further, the left and right end faces of the light emitting layer 12 have a resonant structure in which the reflectivity is set appropriately, whereby laser oscillation is performed.

The n-type transparent conductive film 41 and the p-type photonic crystal layer 42 are made of a material having a refractive index lower than that of the light emitting layer 12. For example, the n-type transparent conductive film 41 is composed of a transparent conductive film such as tin dioxide (SnO ₂ ), indium tin oxide (ITO), indium oxide (In ₂ O ₃ ), and zinc oxide (ZnO). The thickness is, for example, 3 μm. The p-type photonic crystal layer 42 is made of, for example, a photonic crystal made of silicon (Si) and has a thickness of 1 μm, for example.

  The light emitting element 40 is produced as follows, for example. First, after the n-type transparent conductive film 41 is formed on the substrate 11 by, for example, sputtering or vapor deposition, the light emitting layer 12 is formed on the n-type transparent conductive film 41 by the above-described method. Next, the p-type photonic crystal layer 42 is formed on the light emitting layer 12 by, for example, a combination of electron beam drawing and dry etching.

In the light emitting element 40 of the present embodiment, since the light emitting layer 12 is composed of SiO _x and erbium, when a voltage is applied between the n-type transparent conductive film 41 and the p-type photonic crystal layer 42. In the light emitting layer 12, recombination of electrons and holes occurs, and infrared light is emitted by the electrons in the erbium ions excited by the recombination. This light is reflected by the left and right end faces of the light emitting layer 12 and is emitted to the outside as a beam, like the light emitting element 30. Further, since the n-type transparent conductive film 41 and the p-type photonic crystal layer 42 have a refractive index lower than that of the light emitting layer 12, efficient light confinement is possible.

  Further, since the p-type photonic crystal layer 42 is composed of, for example, a photonic crystal such as silicon, the average refractive index can be lowered by increasing the density of air holes in the crystal. The light confinement efficiency in the light emitting layer 12 is improved.

[Fifth Embodiment]
FIG. 7 shows a cross-sectional structure of a light emitting device 50 manufactured by providing a light confinement structure (laser structure) in the light emitting device 10 according to the first embodiment.

  In the light emitting element 50, a p-type transparent conductive film 51 and an n-type transparent conductive film 52 as a pair of cladding layers are provided above and below the light emitting layer 12 in the light emitting element 10. Further, the left and right end faces of the light emitting layer 12 have a resonant structure in which the reflectivity is set appropriately, whereby laser oscillation is performed.

The p-type transparent conductive film 51 and the n-type transparent conductive film 52 are made of a material having a refractive index lower than that of the light emitting layer 12 and a band gap larger than that of the light emitting layer 12. For example, the n-type transparent conductive film 52 is composed of at least one transparent conductive film of tin dioxide, indium tin oxide, indium oxide (In ₂ O ₃ ), and zinc oxide (ZnO). Zinc oxide (ZnO), tin dioxide (SnO ₂ ), nickel oxide (NiO), copper oxide (Cu ₂ O), iron oxide (FeO), bismuth oxide (Bi ₂ O ₃ ), praseodymium oxide (Pr ₂ O) ₃ ), thallium oxide (Tl ₂ O ₃ ), delafossite (CuAlO ₂ ), and strontium copper oxide (SrCu ₂ O ₂ ). These materials have a polycrystalline or amorphous structure and can be directly formed on a glass substrate, which leads to simplification of the manufacturing process and cost reduction. The film thicknesses of the p-type transparent conductive film 51 and the n-type transparent conductive film 52 are each about 1 μm, for example, and the formation method is, for example, a sputtering method or a vapor deposition method.

Also in the light emitting element 50 of the present embodiment, since the light emitting layer 12 is composed of SiO _x and erbium, when a voltage is applied to the p-type transparent conductive film 51 and the n-type transparent conductive film 52, the light emitting layer 12, recombination of electrons and holes occurs, and infrared light is emitted by electrons in the erbium ions excited by the recombination. This light is reflected by the left and right end faces of the light emitting layer 12 and is emitted to the outside as a beam, like the light emitting element 30. At this time, since the n-type transparent conductive film 51 and the p-type transparent conductive film 52 have a refractive index lower than the refractive index of the light emitting layer 12, efficient light confinement becomes possible.

Next, operations and effects of the n-type transparent conductive film 51 and the p-type transparent conductive film 52 having a larger band gap than the light emitting layer 12 will be described with reference to FIG. FIG. 8 shows a schematic diagram (A) of the light-emitting element 50 and a light-emitting element having a structure in which an SiO ₂ light-emitting layer 102 to which erbium is added is sandwiched between an n-type silicon layer 101 and a p-type silicon layer 103 as a comparative example. A schematic diagram (B) of 100 (Non-Patent Document 2) is shown. FIG. (C) is a schematic diagram showing the light emission principle of the light emitting element 50.

  In the light emitting element 100, since the band gap of the light emitting layer 102 is larger than that of the n type silicon layer 101 and the p type silicon layer 103 sandwiching the light emitting layer 102, the light emitting layer 102 has a band gap from the n type silicon layer 101 and the p type silicon layer 103 to the light emitting layer 102. The barrier for carrier injection is high. For this reason, carrier confinement cannot be performed in the light emitting layer 102, and quantum efficiency falls. In addition, current operation (Fowler-Nordheim current) is caused by a tunnel effect to an insulating film having a large band gap, so that the operating voltage becomes as high as 20 to 70V. Furthermore, since dielectric breakdown occurs due to carrier trapping in the silicon oxide film, there arises a problem that the device life is remarkably shortened.

On the other hand, in the light emitting device 50 of the present embodiment, the band gap of SiO _x is about 1 to 4 eV, and the band gap is smaller than that of the SiO ₂ . Further, since the light emitting layer 12 containing SiO _x is sandwiched between transparent conductive films having a band gap of about 4 eV, there is no barrier in carrier injection from the transparent conductive film to the light emitting layer 12. Thereby, carriers are effectively confined in the light emitting layer 12, and the carrier density is increased. Therefore, the quantum efficiency is greatly improved, and the lifetime of the device is greatly extended. Also, the operating voltage is reduced to about a band gap energy (several V) and can be driven with about 1/10 of the conventional power consumption, so that a current injection type light emitting element that does not require photoexcitation at all is realized. Is possible. According to this, the mounting in the integrated circuit is facilitated and the size can be reduced as compared with the light emitting element that must emit the excitation light different from the signal light in the integrated circuit.

Hereinafter, examples according to the first embodiment of the present invention will be described in detail.
(Example)
First, an experiment for measuring the optical band gap of the light emitting layer 12 was performed. At this time, silicon monoxide and erbium having a composition ratio of 1% with respect to silicon monoxide are simultaneously deposited by resistance heating deposition on the silicon substrate 10, and then heat treatment (annealing treatment) is performed to emit light having a thickness of 1.5 μm. What was produced by forming the layer 12 was used. Moreover, the temperature of heat processing was 350 degreeC, 550 degreeC, and 750 degreeC. At each temperature, a HeNe laser (wavelength 633 nm) was irradiated at room temperature, the transmittance in the light emitting layer 12 was measured, and the corresponding absorption coefficient (absorption coefficient = −ln (transmittance) / film thickness) was obtained. . The results are shown in FIG. 9 and FIG.

  As shown in FIG. 10, the optical band gap was obtained by fitting the absorption coefficient curve as shown in the figure, and found to be 2.8 eV at a heat treatment temperature of 350 ° C., 2.6 eV at 550 ° C., It was 2.35 eV at 750 ° C., and it was found that the band gap was greatly reduced. This result is shown in FIG. 11 as the relationship of the band gap to the heat treatment temperature.

  Next, the emission intensity (PL intensity) with respect to the emission wavelength (PL wavelength) in the light emitting layer 12 was measured. The measurement result of the PL spectrum is shown in FIG. At this time, the heat treatment temperatures were 350 ° C. (A in the drawing), 450 ° C. (B in the drawing), 550 ° C. (C in the drawing), 650 ° C. (D in the drawing), 750 ° C. (E in the drawing), and 850 ° C. (F in the figure) was set. From this measurement result, it became clear that a light emission peak was obtained in a wavelength band of 1.5 μm. In addition, it was confirmed that light emission in the 1.5 μm wavelength band was confirmed using a wavelength (633 nm) different from the excitation wavelength of erbium, and thus the excitation energy range was greatly expanded.

FIG. 13 shows the relationship between the light emission intensity (the peak value of the light emission intensity) in the vicinity of a wavelength of 1.5 μm with respect to the heat treatment temperature. As a result, the emission intensity in the 1.5 μm wavelength band gradually increases as the heat treatment temperature is increased (A and B in the figure) and reaches a maximum (C in the figure) at 550 ° C. and reaches 550 ° C. When it exceeded, it showed a decreasing trend (D, E, F in the figure). This is presumably because at 350 ° C. to 550 ° C., as the temperature increases, the bonding between erbium atoms and oxygen atoms is promoted and ionized to be optically activated. On the other hand, if the temperature exceeds 550 ° C., the tendency of SiO _x to separate into silicon and silicon dioxide increases, so that erbium is taken into silicon and becomes non-ionized and optically inactive.

In addition, when the composition of SiO _x at the time of heat treatment at 550 ° C. at which the emission intensity in the wavelength band of 1.5 μm is maximum was measured by X-ray photoelectron spectroscopy (XPS), x = 1. A result of .27 was obtained. At this time, as shown in FIG. 14, the composition was measured in the depth direction (from the surface of the SiO _x layer to the interface with the Si substrate), and the composition at a depth of 34 minutes (Si: 42.8 atomic%). , O: 54.3 atomic%, Er: 2.9 atomic%), the above results were obtained.

  Moreover, in FIG. 15, the result of having measured PL spectrum for every content of erbium is shown. FIG. 16 shows a summary of the emission intensity (emission peak value) in the vicinity of a wavelength of 1.5 μm with respect to the erbium content. The erbium content was 1 atomic%, 5 atomic%, and 10 atomic%. As shown in these figures, when the erbium content was 10 atomic% or less, the emission peak was improved in the wavelength band of 1.5 μm. Moreover, the emission peak gradually increased as the content increased from 0 to 5 atom%, and the emission peak tended to gradually decrease when the content exceeded 5 atom%.

The light emitting device and the method for producing the same of the present invention can be used for, for example, the following applications.
(1) Optical signal transmission in an ultra-high density integrated circuit (2) Low-cost connection between an optical fiber and a computer by forming an integrated circuit and an optical device on a single substrate (3) A signal processing apparatus for optical communication ( Router) and low power consumption (4) Ultra-compact erbium-doped optical fiber amplifier (EDFA)

It is sectional drawing showing schematic structure of the light emitting element which concerns on 1st Embodiment. It is sectional drawing for demonstrating the manufacturing process of the light emitting element shown in FIG. It is sectional drawing (A) showing schematic structure of the light emitting element which concerns on 2nd Embodiment, and the schematic diagram (B) of the energy band showing the light emission principle. It is sectional drawing showing schematic structure of the other light emitting element which concerns on 2nd Embodiment. It is sectional drawing (A) showing schematic structure of the light emitting element which concerns on 3rd Embodiment, and the schematic diagram (B) of the energy band showing the light emission principle. It is sectional drawing showing schematic structure of the light emitting element which concerns on 4th Embodiment. It is sectional drawing showing schematic structure of the light emitting element which concerns on 5th Embodiment. It is a schematic diagram of the energy band showing the light emission principle of the light emitting element which concerns on 5th Embodiment. It is a characteristic view showing the wavelength dependence of the transmittance | permeability in the light emitting layer which concerns on an Example. It is a characteristic view showing the wavelength dependence of the absorption coefficient in the light emitting layer which concerns on an Example. It is a characteristic view showing the heat treatment temperature dependence of the band gap in the light emitting layer which concerns on an Example. It is a characteristic view showing the relationship (PL spectrum) of PL intensity with respect to PL wavelength of the light emitting element which concerns on an Example. It is a characteristic view showing the relationship of the peak value (maximum value) of PL intensity with respect to the temperature of the heat processing of the light emitting element which concerns on an Example. It is a diagram for explaining a method of measuring the SiO _x composition of the light emitting device according to the embodiment. It is a figure which shows PL spectrum for every erbium content of the light emitting element which concerns on an Example. It is a figure which shows the peak value of PL intensity with respect to erbium content of the light emitting element which concerns on an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 20, 30, 40, 50 ... Light emitting element, 11 ... Substrate, 12 ... Light emitting layer, 21 ... p-type current injection layer, 22 ... ZnO light emitting layer, 23 ... n-type current injection layer, 31 ... n-type silicon layer 32 ... p-type silicon layer, 41, 52 ... n-type transparent conductive film, 42 ... p-type photonic crystal layer, 51 ... p-type transparent conductive film.

Claims (8)

A light emitting device comprising: a light emitting layer containing silicon oxide (SiO _x , 0.5 <x <1.5) and erbium (Er). The light emitting element according to claim 1, further comprising a pair of clad layers with the light emitting layer interposed therebetween, wherein each of the clad layers has a refractive index lower than a refractive index of the light emitting layer. One of the cladding layers is composed of a first transparent conductive film, and the other of the cladding layers is composed of a second transparent conductive film,
The light emitting element according to claim 2, wherein the first transparent conductive film and the second transparent conductive film have a band gap larger than that of the light emitting layer. The first transparent conductive film includes at least one of tin dioxide (SnO ₂ ), indium tin oxide (ITO), indium oxide (In ₂ O ₃ ), and zinc oxide (ZnO). The light emitting device according to claim 3, wherein The second transparent conductive film includes zinc oxide (ZnO), tin dioxide (SnO ₂ ), nickel oxide (NiO), copper oxide (Cu ₂ O), iron oxide (FeO), bismuth oxide (Bi ₂ O ₃ ), It contains at least one of praseodymium oxide (Pr ₂ O ₃ ), thallium oxide (Tl ₂ O ₃ ), delafossite (CuAlO ₂ ) and strontium copper oxide (SrCu ₂ O ₂ ). 4. The light emitting device according to 4. 2. The light-emitting element according to claim 1, wherein the content of the erbium in the light-emitting layer is 0.5 atomic% or more and 10 atomic% or less. A light emitting element comprising a light emitting layer containing silicon (Si), oxygen (O), and erbium (Er) and having an optical band gap of 1.1 to 4.0. Forming a thin film by simultaneously depositing silicon monoxide (SiO) and erbium (Er) on a substrate by resistance heating vapor deposition or sputtering;
And a step of forming a light emitting layer by subjecting the thin film to a heat treatment at a temperature of 350 ° C. or higher and 650 ° C. or lower.

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