KR101917300B1 - Photo Active Layer by Precise Control and Activation of Silicon Quantum Dot and the Fabrication Method thereof - Google Patents

Abstract

The present invention relates to a silicon quantum dot photoactive layer and a method of manufacturing the same, and more particularly, to a method of manufacturing a silicon quantum dot photoactive layer according to the present invention, which comprises the steps of: a) forming a silicon-rich intrinsic silicon compound layer; b) forming a silicon quantum dot layer in which a silicon quantum dot is formed in a medium which is a silicon compound by irradiating a pulsed laser to the intrinsic silicon compound layer; And c) implanting doping elements into the silicon quantum dot layer and activating the doping element to produce a photoactive layer.

Description

[0001] The present invention relates to a photoactive layer by precise control and activation of a silicon quantum dot, and a manufacturing method thereof. [0002]

The present invention relates to a photoactive layer made of silicon quantum dots and a method for producing the same, and more particularly, to a photoactive layer having uniform and fine quantum dots formed at high density, a device including the same, and a method for manufacturing the same.

The solar cell industry is divided into first generation, second generation and third generation in consideration of manufacturing cost and efficiency. The first-generation solar cell is a crystalline silicon solar cell that has been developed over the past several decades and now accounts for more than 80% of all solar cells. The second-generation solar cell is a thin-film solar cell such as amorphous silicon, compound, or organic thin film, which is a relatively high solar cell and has a high manufacturing cost. And a new concept solar cell using nanostructure and quantum dot as a solar cell.

Crystalline silicon solar cells, which are first-generation solar cells, have already reached technological limits according to the efficiency limit (ex: Shockely-Queisser limit). Currently, research and development of second generation thin film solar cells is actively conducted. However, It is required to develop a low-cost, high-efficiency third-generation solar cell.

A silicon quantum dot solar cell was proposed as one of the possible third generation solar cells. Theoretically, 29% of single junctions and 47.5% of multiple junctions are expected. However, to date, the theoretical efficiency has not been close to the efficiency.

Technical difficulties of silicon quantum dot solar cell, which obstructs the implementation of high efficiency device, include: i) difficulty in controlling density and size of silicon quantum dots; ii) deterioration of substrate characteristics due to high temperature heat treatment accompanying formation of quantum dots; and iii) (Ex: formation of pn junction or emitter) independently of each other.

The Applicant has found that by heat treating a silicon compound layer containing an excess amount of silicon more than the stoichiometric ratio through the Korean Registered Patent No. 1060014, the Korean Registered Patent No. 1189686, and the Korean Registered Patent No. 1670286, silicon quantum dots A technique of forming a conductive layer which is a polycrystalline silicon layer doped with impurities between silicon quantum dot layers in order to reduce the series resistance of a photoactive layer containing silicon quantum dots and a technique of forming a conductive layer containing an amorphous silicon compound layer and a non- And a technique of increasing the density of the silicon quantum dots by heat treatment after alternately stacking the silicon-excess silicon compound layers having the silicon-containing silicon compound layer having the silicon-rich silicon compound layer.

However, the above-mentioned conventional methods can produce quantum dots to some extent. However, it is difficult to control the size and density of the quantum dots. The problem of the characteristic deterioration due to the high-temperature heat treatment accompanying the formation of the quantum dots, (Ex: formation of a pn junction or emitter) can not be independently controlled. Therefore, it is necessary to develop a technique to solve this problem.

Korean Patent No. 1060014, Korean Patent No. 1189686, Korean Patent No. 1670286

 SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of controlling density and size of quantum dots, preventing deterioration due to high-temperature heat treatment, And a method of manufacturing an optical element including the photoactive layer.

It is still another object of the present invention to provide a high-efficiency photoactive layer in which fine and uniform quantum dots are formed at a high density and an optical element including the same.

The method of manufacturing a silicon quantum dot photoactive layer according to the present invention comprises the steps of: a) forming a silicon-rich intrinsic silicon compound layer; b) forming a silicon quantum dot layer in which a silicon quantum dot is formed in a medium which is a silicon compound by irradiating a pulsed laser to the intrinsic silicon compound layer; And c) implanting doping elements into the silicon quantum dot layer and activating the doping element to produce a photoactive layer.

In the method of manufacturing a photoactive layer according to an embodiment of the present invention, in step b), the size and density of the silicon quantum dots can be controlled by the energy of the pulse laser.

In the production method of the optically active layer according to an embodiment of the invention, the b) fluence of the pulse laser is irradiated in step seuneun may be 0.1mJ / cm ² to 200mJ / cm ^2.

In the method of manufacturing a photoactive layer according to an embodiment of the present invention, the pulse laser irradiated in the step b) may be a near infrared ray to an infrared ray pulse laser.

In the method of manufacturing a photoactive layer according to an embodiment of the present invention, the silicon compound layer in step a) may be silicon oxide, silicon nitride, or silicon oxynitride.

In the method for manufacturing a photoactive layer according to an embodiment of the present invention, in step (a), the silicon-rich intrinsic silicon compound layer may satisfy the following relational expression (1).

(Relational expression 1)

0.5? Ratio (SC) / Ratio (STO)? 0.9

Ratio (SC) is the silicon content contained in the silicon compound layer in step a), the silicon content is the elemental consumption of bonding elements which are silicon-to-silicon-forming elements forming silicon compounds, and Ratio (STO) Based on the stoichiometric ratio of the above bonded elements.

In the method of manufacturing a photoactive layer according to an embodiment of the present invention, the step a) and the step b) may be carried out by a single unit process before or after the doping element implantation in the step c) or the step c) The unit process can be repeatedly performed.

The method of manufacturing an optical device according to the present invention comprises the steps of: forming a silicon quantum dot photoactive layer on a silicon substrate on which a lower electrode is formed and doped with a first type impurity by the above-described method for producing a photoactive layer, Preparing a silicon quantum dot photoactive layer by implanting complementary impurities; And forming an upper electrode on the silicon quantum dot photoactive layer.

In the method of manufacturing an optical device according to an embodiment of the present invention, the optical device may be a photovoltaic device or a light emitting device.

The present invention includes a silicon quantum dot photoactive layer prepared by the above-described method for producing a photoactive layer.

The present invention includes an optical element manufactured by the above-described method for manufacturing an optical element.

The silicon quantum dot photoactive layer according to the present invention may be a layer in which silicon quantum dots satisfying the following relational expression 2 and the following relational expression 3 are dispersed in the silicon compound medium.

(Relational expression 2)

3 nm < / = D _m < / = 6 nm

In Equation 2, D _m is the average diameter of the silicon quantum dots dispersed in the medium.

(Relational expression 3)

0.9D _m ? D ≤1.1D _m

In Equation 3, D is the diameter of the silicon quantum dots dispersed in the medium, and D _m is the average diameter of the silicon quantum dots.

In the photoactive layer according to an embodiment of the present invention, the density of the silicon quantum dots may be 1.0 x 10 ¹⁷ / cm ³ to 1.0 x 10 ¹⁹ / cm ³ .

The method for manufacturing a photoactive layer according to the present invention is a method for manufacturing a photoactive layer in which a silicon quantum dot having a small size, a high density and a uniform size is formed as the silicon compound layer is instantaneously and intensively heated and quenched by a pulsed laser There are advantages. In addition, since the silicon quantum dots having a uniform size are formed at a high density, the photoactive layer manufacturing method according to the present invention can produce tunneling of electrons with a narrow gap between the quantum dots, There is an advantage. Further, by switching the silicon compound layer to the silicon quantum dot layer by pulsed laser irradiation, there is an advantage that components existing in the lower portion of the silicon compound layer, such as a substrate, are free from thermal damage. Further, after the silicon compound layer is converted into the silicon quantum dot layer and the implantation and activation of the impurity (doping element) for controlling the electrical characteristics of the silicon quantum dot layer are performed, the generation of the quantum dot and the control of the electrical characteristics of the silicon quantum dot layer are independent So that the degree of activation of the doping element can be independently controlled and the undesired diffusion of the doping element is prevented.

1 is a process diagram illustrating a method of manufacturing a photoactive layer according to an embodiment of the present invention,
FIG. 2 is a process diagram showing a method of manufacturing an optical device according to an embodiment of the present invention,
FIG. 3 is a diagram illustrating the measurement of light-emitting characteristics of the photoactive layer manufactured by the conventional heat treatment and the photoactive layer manufactured according to an embodiment of the present invention,
4 is a transmission electron microscope (SEM) image of a photoactive layer prepared according to an embodiment of the present invention.

Hereinafter, the photoactive layer according to the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings. The following drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms, and the following drawings may be exaggerated in order to clarify the spirit of the present invention. Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

In describing the present invention, the photoactive layer includes the meaning of a light receiving substance that photoelectron-light hole pairs are generated by receiving light containing sunlight, and independently of this, a photoactive Lt; RTI ID = 0.0 > quantum dots < / RTI > of the layer.

The method of manufacturing a silicon quantum dot photoactive layer according to the present invention comprises the steps of: a) forming a silicon-rich intrinsic silicon compound layer; b) forming a silicon quantum dot layer in which a silicon quantum dot is formed in a medium which is a silicon compound by irradiating a pulsed laser to the intrinsic silicon compound layer; And c) implanting doping elements into the silicon quantum dot layer and activating the doping element to produce a photoactive layer.

That is, the method of manufacturing a photoactive layer according to the present invention comprises the steps of forming a silicon-rich silicon compound layer, forming an intrinsic silicon compound layer not containing a dopant for controlling electrical characteristics, The silicon compound layer is converted into a silicon low-point layer having a silicon quantum dot in the medium, and then a doping element is implanted into the silicon quantum dot layer to activate the photoactive layer. Hereinafter, unless otherwise specified, the silicon compound layer means a silicon-rich intrinsic silicon compound layer.

As described above, the method of manufacturing a photoactive layer according to the present invention can form a silicon quantum dot having a small size, a high density and a uniform size by heating a silicon compound layer momentarily and intensively by a pulse laser, The spacing between the quantum dots is narrow, tunneling of electrons is easily generated, and a photoactive layer having increased efficiency can be manufactured. Further, by switching the silicon compound layer to the silicon quantum dot layer by pulsed laser irradiation, there is an advantage that components existing in the lower part of the silicon compound layer, such as a substrate, are free from thermal damage. Further, after the silicon compound layer is converted into the silicon quantum dot layer and the implantation and activation of the impurity (doping element) for controlling the electrical characteristics of the silicon quantum dot layer is performed, the formation of the quantum dots and the control of the electrical characteristics of the silicon quantum dot layer are independent And the degree of activation of the doping element can be independently controlled.

FIG. 1 is a process diagram showing a process of manufacturing a photoactive layer according to an embodiment of the present invention. Referring to FIG. As shown in FIG. 1, the photoactive layer may be produced by depositing a silicon compound layer, pulsed laser irradiation, doping of the doping element, and activation of the doped element.

The silicon compound layer may be silicon oxide, silicon nitride or silicon oxynitride. That is, when an element that bonds with silicon to form a silicon compound is referred to as a bonding element, the bonding element may be oxygen, nitrogen, or oxygen and nitrogen. In the present invention, the silicon compound layer is not limited to silicon oxide, silicon nitride or silicon oxynitride. However, in the produced photoactive layer, the silicon quantum dots may absorb light introduced through the medium, As the light is emitted to the outside through the medium, the silicone compound of the silicon compound layer is preferably a transparent silicone compound which is advantageous for absorption or transmission of light. At this time, an example of the transparent silicon compound is silicon oxide.

The silicon compound layer may contain an excess amount of silicon more than the stoichiometric ratio while the original consumption between the silicon and the bonding element forming the silicon compound deviates from the stoichiometric ratio. This composition of silicon richness provides a driving force by which silicon quantum dots are generated.

As a specific example, the silicon quantum dots can be generated by the energy of the pulsed laser to be irradiated, and the silicon quantum dots can be formed in the island form while forming the high-density silicon quantum dots. Satisfies the following relational expression (1).

(Relational expression 1)

0.5? Ratio (SC) / Ratio (STO)? 0.9

Ratio (SC) is the silicon content contained in the silicon compound layer in step a), the silicon content is the elemental consumption of bonding elements which are silicon-to-silicon-forming elements forming silicon compounds, and Ratio (STO) Based on the stoichiometric ratio of the above bonded elements. As a specific example, when the bonding element is oxygen, the silicon compound layer may have a composition of SiO _x (x is a real number of 1.0 to 1.8).

The silicon compound layer can be formed using chemical vapor deposition, physical vapor deposition, physical-chemical vapor deposition, plasma deposition, atomic layer deposition, or thermal vapor deposition used in thin film formation in a conventional semiconductor process, It is needless to say that the silicon compound layer having a controlled composition can be produced by controlling the raw consumption of the silicon element relative to the bonding element to be injected at the time of deposition or by controlling the composition of the target material.

After the formation of the silicon compound layer, the silicon compound layer can be converted into a silicon quantum dot layer in which silicon quantum dots are formed in the medium, which is a silicon compound, by pulsed laser irradiation. In this case, the medium may be an undoped-state intrinsic silicon compound, and the silicon compound of the medium may have a composition close to the stoichiometric ratio to the stoichiometric ratio as the excess silicon is consumed as the silicon quantum dots.

The silicon compound layer is heated extremely quickly by irradiating the pulsed laser to convert the silicon compound layer into the silicon quantum dot layer and at the same time the region other than the region to which the pulse laser is irradiated is in a relatively cold state, Due to the seif-quenching effect, nucleation of the silicon quantum dots is actively generated, growth of the quantum dots is prevented, and extremely fine quantum dots can be formed at high density, which is advantageous. In addition, the pulsed laser is advantageous because it can control the exact depth of the region heated by the laser, is advantageous for commercialization because the processing speed is very fast, and quantum dots of uniform quality can be formed even in a large area. In addition, complicated deposition processes such as alternating deposition of different hetero-layers for the miniaturization of quantum dots can be excluded, and a simple deposition process for depositing a single silicon-rich silicon compound layer enables uniform and highly dense quantum dots Can be formed.

In general, it is customary that the photoactive layer is simultaneously produced during the manufacturing process of the optical device. Accordingly, a lower component for driving the optical device exists in the lower portion of the photoactive layer. For example, an n-type or p-type silicon semiconductor layer may exist under the photoactive layer, for example, a photovoltaic device or a light emitting device. At this time, when the silicon compound layer is converted into the silicon quantum dot layer through the heat treatment as in the prior art, the n-type or p-type silicon semiconductor layer is thermally deteriorated to lower the efficiency of the optical device. However, when the silicon compound layer is converted into the silicon quantum dot layer by irradiating a pulsed laser according to the present invention, even if the silicon compound layer has a thickness of the order of several tens of nanometers, other components existing under the silicon compound layer are damaged from thermal damage There is a free advantage.

As described above, as the silicon compound layer is converted into the silicon quantum dot layer by the pulse laser irradiation, fine quantum dots are formed at a high density and uniformly, and stable and easy electron tunneling can be achieved. Accordingly, it is possible to realize a relatively thick photoactive layer in the case of pulsed laser irradiation, compared with a heat treatment method in which a thickness limitation is caused by a high series resistance. As a specific example, the thickness of the silicon compound layer (silicon quantum dot layer or photoactive layer) may be 50 to 200 nm, more specifically, 90 to 120 nm.

Further, as described above, as the silicon compound layer is converted into the silicon quantum dot layer by the pulse laser irradiation, the region other than the region irradiated with the pulse laser can be thermally stable. Thus, the process of forming the silicon compound layer and the step of converting into the silicon quantum dot layer by the pulsed laser irradiation before the activation step after the impurity implantation in the step c) or the c) This unit process may be repeated (e.g., two to five times). As a result, a photoactive layer having a thick and uniform density and size of the quantum dots can be manufactured.

In the method of manufacturing the photoactive layer according to an embodiment of the present invention, the size and density of the silicon quantum dots can be controlled by the energy of the pulse laser irradiated in step b). Specifically, the pulsed laser can generate nucleation and growth of silicon quantum dots within a localized region as it is heated to a region limited by the laser irradiation. Further, the silicon compound layer can provide a constant driving force by the silicon-rich composition. The size and density of the silicon quantum dots can be controlled precisely and reproducibly according to the energy (fluence, energy density) of the pulse laser irradiated only on the silicon compound layer by the conditions of the localized reaction field and the constant driving force. In particular, the size control of the quantum dots means that the emission center wavelength of the photoactive layer can be controlled by adjusting the fluorescence of the pulsed laser to be irradiated.

As a specific example, the fluence of the pulsed laser irradiated in step b) may be from 0.1 mJ / cm ² to 200 mJ / cm ² , and more preferably from 50 mJ / cm ² to 150 mJ / cm ² . There is a risk that the silicon compound layer is physically deformed or damaged due to the energy of the pulsed laser to be irradiated when the fluence of the pulsed laser to be irradiated is excessively high beyond the prescribed range. Also, if the fluence of the pulsed laser to be irradiated is excessively low below the indicated range, there is a risk that the silicon quantum dots are not generated or the density of silicon quantum dots is lowered.

As described above, the fluence of the pulse laser irradiated in the step b) is controlled to be 0.1 mJ / cm ² to 200 mJ / cm ² , preferably 50 mJ / cm ² to 150 mJ / cm ² , To increase the size of the silicon quantum dots and to reduce the fluence of the laser so that relatively fine silicon quantum dots can be formed with a relatively high density.

The pulse laser irradiated in step b) can be used as long as it is a pulse laser of a wavelength capable of heating the silicon compound layer without damaging the silicon compound layer. As a specific example, the pulsed laser to be irradiated may be near-infrared or infrared pulsed laser. As a practical example, the central wavelength of the pulsed laser to be irradiated may be 750 to 1100 nm, preferably 750 nm to 850 nm. The pulsed laser irradiated in step b) may be a pulse single pulse laser, has an repetition rate of 1 KHz, and may have a pulse width of 50 to 200 fs. Such laser oscillation wavelength, repetition rate, and pulse width are advantageous because they can stably prevent damages of the silicon compound layer and thermal damage of other components while forming high-density fine and uniform silicon quantum dots.

After the silicon compound layer is converted into the silicon quantum dot layer by pulsed laser irradiation, a step of implanting the doping element into the silicon quantum dot layer and activating the doping element to manufacture the photoactive layer may be performed. This means that the adjustment of the electrical characteristics of the photoactive layer by the doping element is performed independently of the silicon quantum dot layer formation (conversion). Thus, unwanted diffusion of the doping element is prevented and effective activation can be achieved.

The doping element may be an n-type or p-type impurity. Specifically, the n-type impurity may be a Group 15 element including phosphorus, and the p-type impurity may be a Group 13 element including boron or aluminum.

Implantation of the doping element can be performed through the implant. Implantation is advantageous because it allows rapid, uniform, and precise dosing of doping elements at controlled depths.

The doping element may be implanted at a dose of 5.0 x 10 ¹⁹ atoms / cm ³ to 7.0 x 10 ²¹ atoms / cm ^3. The doses of such doping elements may be formed by forming a pn junction (emitter) with a semiconductor in contact with the photoactive layer, Is a favorable DOS.

After the doping of the doping element is performed, activation of the silicon quantum dot layer doped with the doping element may be performed for activation of the doping element. The heat treatment for activating the doping element may be performed at a temperature at which the doping element can be activated while preventing unwanted diffusion of the doping element implanted at the designed depth and concentration through the implant.

As is known, when a silicon compound containing an excessive amount of silicon is heat-treated to prepare a doped silicon quantum dot layer, heat treatment at a relatively high temperature is required. However, activation of the doping element requires a temperature Lt; / RTI > As a specific example, when the silicon compound is silicon oxide, heat treatment at a temperature of 1000 캜 or more is required for forming a quantum dot, but activation of a doping element is usually performed at a temperature of less than 1000 캜.

A method of manufacturing a photoactive layer according to an embodiment of the present invention includes the steps of: forming a silicon quantum dot layer in an undoped state by irradiating a pulsed laser to an undoped silicon compound layer as described above, As the doping and activation of the doping element is performed, the doping element implanted can be activated by heat treatment at a temperature known as the activation temperature of the doping element. Specifically, the heat treatment for activation of the doping element may be performed at a temperature of 400 to 900 캜. The quantum dot formation and the injection of the doping element independently and the activation at low temperature enables the stable activation of the doping element while maintaining the designed doping profile and doping concentration and the activation of the component (e.g., substrate, electrode, p Type or n-type semiconductor, etc.) can be prevented.

The present invention includes a method of manufacturing an optical device using the above-described photoactive layer production method. In this case, the optical device may include a photovoltaic device (a solar cell) or a light emitting device. Accordingly, the present invention can provide a method of manufacturing a photovoltaic device using the above- And a manufacturing method of the light emitting device using the manufacturing method.

FIG. 2 is a process diagram illustrating a method of manufacturing an optical device according to an embodiment of the present invention. Specifically, a method of manufacturing an optical device according to an embodiment of the present invention includes forming a lower electrode 120, The silicon quantum dot photoactive layer 500 is prepared on the doped silicon substrate 110 by the above-described method of manufacturing the photoactive layer. The silicon quantum dot photoactive layer 500 is doped with a dopant complementary to the first type impurity, Lt; / RTI > And forming an upper electrode 600 on the silicon quantum dot photoactive layer 500.

2, a silicon-rich intrinsic silicon compound layer 200 is formed on a silicon substrate 110 on which a lower electrode 120 is formed and doped with a first-type impurity. Thereafter, The silicon quantum dot layer 300 in which the silicon quantum dots 320 are formed in the silicon compound medium 310 can be manufactured by pulsed laser irradiation. Thereafter, a doping element, which is an impurity, is implanted into the silicon quantum dot layer 300 that does not contain an impurity for adjusting the electrical characteristics, and a silicon quantum dot 420 doped with a doping element in the doped medium 410 A doped silicon quantum dot layer 400 can be manufactured. In this case, when the silicon substrate 110 is an n-type silicon substrate containing an n-type impurity, the doping element injected into the silicon quantum dot layer 300 may be a p-type impurity. Alternatively, In the case of a p-type silicon substrate containing an impurity, the doping element injected into the silicon quantum dot layer 300 may be an n-type impurity.

The doped silicon quantum dot layer 400 is doped with a doping element in a doped element-doped and doped silicon compound medium 510 through a heat treatment to activate the doping element, Layer 500 may be fabricated.

The upper electrode 600 may be formed on the photoactive layer 500. The upper electrode 600 may have a structure advantageous to the operation of the device according to a target optical device. In a specific example, when the optical element is a photodiode, the upper electrode 600 may be a transparent conductive film (transparent electrode). The transparent conductive film can serve not only as a transparent window through which incident light passes, but also as an electrode for collecting electrons generated by incident light. The transparent conductive film may be a material used as a transparent front electrode in a conventional solar cell. Specific and non-limiting examples of the transparent conductive film include ZnO, aluminuim-doped zinc oxide (AZO), Ga-doped zinc oxide (GZO), boron-doped zinc oxide (BZO), indium tin oxide (ITO) tin oxide, graphene, or mixtures thereof. It is needless to say that a metal grid electrode (or a metal pad) may be further provided on an upper portion of the transparent conductive film in order to effectively transfer the photocurrent collected in the transparent conductive film when the desired photon is the photovoltaic device. In another example, when the photonic device is an auto-light emitting device, the upper electrode 600 may be a metal film. The thickness of each of the upper electrode and the lower electrode is not particularly limited, but may be 50 nm to 2000 nm, specifically 50 nm to 800 nm, and more specifically, 100 nm to 600 nm. The upper electrode and the lower electrode may be manufactured by a common printing method such as screen printing, stencil printing, or the like, or a conventional deposition method using physical vapor deposition (PVD) or chemical vapor deposition (CVD), respectively.

The present invention includes an optical element manufactured by the above-described method for manufacturing an optical element.

The present invention includes a silicon quantum dot photoactive layer prepared by the above-described method for producing a photoactive layer.

The silicon quantum dot photoactive layer according to the present invention is advantageous in that extremely uniform and fine silicon quantum dots are dispersed evenly in the silicon compound medium and have remarkably improved luminous efficiency. At this time, the silicon compound as a medium may be a silicon compound satisfying a stoichiometric ratio, and may be, for example, a silicon oxide, a silicon nitride, or a silicon oxynitride satisfying a stoichiometric ratio.

The other silicon quantum dot photoactive layer according to one embodiment of the present invention may be a layer in which silicon quantum dots satisfying the following relational expression 2 and relational expression 3 are dispersed in the silicon compound medium.

(Relational expression 2)

3 nm < / = D _m < / = 6 nm

In Equation (2), Dm is the average diameter of the silicon quantum dots dispersed in the medium.

(Relational expression 3)

0.9D _m ? D ≤1.1D _m

In Equation 3, D is the diameter of the silicon quantum dots dispersed in the medium, and D _m is the average diameter of the silicon quantum dots.

As in Equation 2, the average diameter of the silicon quantum dots dispersedly embedded in the medium may be 3 to 6 nm. The silicon quantum dots having such a small size are advantageous because they can efficiently absorb visible light in the 400 to 700 nm wavelength band due to the quantum confinement effect.

In addition, according to the above-described relation (3), the silicon quantum dots dispersedly embedded in the medium can have extremely uniform sizes. That is, according to relation 3, the silicon quantum dots dispersed in the medium are D _m ± 0.1D _m (nm), and more specifically, D _m ± 0.5 D _m (nm). < / RTI > This extremely uniform distribution of the size of the silicon quantum dots is a size distribution that can be obtained by generating a silicon quantum dot by irradiating the silicon compound layer with a pulsed laser as described above and provides a reaction field and a silicon compound layer confined to the pulse laser irradiation region A uniform driving force which can be obtained by conditions such as constant driving force, extremely rapid heating and quenching by irradiation of pulsed laser, and the like.

In the photoactive layer according to an embodiment of the present invention, the density of the silicon quantum dots may be 1.0 x 10 ¹⁷ / cm ³ to 1.0 x 10 ¹⁹ / cm ³ . As described above, since the quantum dots having a fine and uniform size are embedded in the medium at an extremely high density, the gap between the quantum dots is uniform and narrow, and electron tunneling in the photoactive layer is easily generated, It can have an excellent optical efficiency.

As described above, since the fine silicon quantum dots having a very uniform size are dispersed and embedded in the silicon compound medium at high density, the efficiency of the optical device can be improved by the thickness of the same photoactive layer compared to the photoactive layer produced by the conventional heat treatment In addition, when a thicker photoactive layer is implemented, the efficiency of the optical device can be further improved by preventing the decrease in efficiency due to an increase in series resistance while improving the absorption rate of sunlight. As a specific example, the thickness of the photoactive layer may be from 50 to 200 nm, more specifically from 90 to 120 nm. In the case of a photoactive layer in which silicon quantum dots are formed in a silicon compound medium by the conventional heat treatment, the efficiency is lowered in the photoactive layer having a thickness of 100 nm or more due to an increase in series resistance. However, since the photoactive layer according to the present invention has extremely easy electron tunneling, the photoactive layer can be formed thicker than the photoactive layer manufactured by conventional heat treatment.

The present invention includes an optical device having the photoactive layer described above. Specifically, the present invention includes a photovoltaic device having the above-described photoactive layer or a light emitting device having the above photoactive layer.

FIG. 3 is a graph showing the relationship between the photoactive layer (previous of FIG. 3) prepared by conventional heat treatment and the light emission of the photoactive layer (Implant Boron of FIG. 3) produced by injecting and activating boron after pulsed laser irradiation according to an embodiment of the present invention (Irradiation light = 405 nm). In detail, the conventional photoactive layer was prepared by depositing a boron-doped SiO _1.6 silicon compound layer on an n-type silicon substrate to a thickness of 110 nm and then heat-treating the resultant structure at 1100 ° C for 60 minutes. The photoactive layer according to an embodiment of the present invention is formed by depositing a silicon compound layer of SiO _{1.6 which} is intrinsic to an identical n-type silicon substrate to a thickness of 110 nm and then forming a Ti: Sapphire (775 nm) laser as a light source, pulsed laser irradiation was applied to the silicon compound layer with fluence of 100 mJ / cm ² to produce a silicon quantum dot layer. Then, boron was implanted into the silicon quantum dot layer at 1.5 x 10 ²¹ atoms / cm ³ Lt; RTI ID = 0.0 > 900 C < / RTI > for 20 minutes.

As can be seen from FIG. 3, the photoactive layer produced according to the present invention has a luminous efficiency that is remarkably increased by 3.5 times or more as compared with the photoactive layer produced by the conventional heat treatment. This increased luminous efficiency is due to the formation of fine and uniformly sized quantum dots at high density.

FIG. 4 is a transmission electron micrograph showing a photoactive layer produced according to an embodiment of the present invention. FIG. As can be seen from FIG. 4, when the photoactive layer is manufactured using the conventional heat treatment, it can be seen that the fine silicon quantum dots having a very uniform size are uniformly formed at a very high density. Specifically, the mean diameter (D _m) of 5 nm, and the size variation of ± 0.5D of the silicon quantum dots within _m (4.75 ~ 5.25 nm) to find out the formed uniformly at a density of 1.0x10 ¹⁸ gae / cm ³ have.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (11)

a) forming a silicon-rich intrinsic silicon compound layer;
b) irradiating the intrinsic silicon compound layer with a near infrared ray or an infrared ray pulsed laser to form a silicon quantum dot layer having silicon quantum dots in a medium which is a silicon compound; And
c) injecting the doping element into the silicon quantum dot layer and activating the dopant element to produce a photoactive layer;
Lt; RTI ID = 0.0 > a < / RTI > silicon quantum dot photoactive layer. The method according to claim 1,
Wherein the size and the density of the silicon quantum dots are controlled by the energy of the pulse laser in the step b). The method according to claim 1,
Wherein the fluence of the pulsed laser irradiated in step b) is from 0.1 mJ / cm ² to 200 mJ / cm ² . delete The method according to claim 1,
Wherein the silicon compound layer in step a) is silicon oxide, silicon nitride or silicon oxynitride. The method according to claim 1,
in step (a), a silicon-rich intrinsic silicon compound layer satisfying the following relational expression (1) is formed.
(Relational expression 1)
0.5? Ratio (SC) / Ratio (STO)? 0.9
(Ratio (SC) is the silicon content contained in the silicon compound layer in step a), the silicon content of the bonding element, which is an element forming silicon compound by bonding with silicon to silicon, Ratio (STO) Lt; RTI ID = 0.0 > silicon-to-bonding < / RTI & The method according to claim 1,
The method of manufacturing a silicon quantum dot photoactive layer in which the unit process is repeatedly performed before the step c), or after the doping element implantation and before the activation of the step c), and a) and b) A silicon quantum dot photoactive layer is prepared by a manufacturing method according to any one of claims 1 to 3 and 5 to 7 on a silicon substrate on which a lower electrode is formed and doped with a first type impurity, Forming a silicon quantum dot photoactive layer by implanting impurities complementary to the first type impurity; And
Forming an upper electrode on the silicon quantum dot photoactive layer;
Wherein the optical device comprises a substrate. 9. The method of claim 8,
Wherein the optical device is a photovoltaic device or a light emitting device.

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