KR20020081551A - Light-emitting diode and method for manufacturing it and light-emitting device apparatus employing it - Google Patents

Abstract

PURPOSE: A light emitting device and a method for manufacturing the same are provided to improve luminous efficiency and light intensity by forming a shallow doping region having quantum confinement effect at p-n junction. CONSTITUTION: The light emitting device comprises a first and a second substrate(11,21), a first and a second doping region(15,25) formed at both surfaces of the substrates, a reflective film(30) formed on the second doping region(25), and electrodes(17,27). The light emitting device further includes control layers(13,23) for controlling the depth of the first and second doping regions(15,25) so as to have an ultra-shallow depth. Thereby, light emitting due to the quantum confinement effect is generated at p-n junction parts(14,24) between the substrates(11,21) and the doping regions(15,25).

Description

Light emitting device and method for manufacturing same and light emitting device apparatus using the same

The present invention relates to a light emitting device having a structure capable of increasing the intensity of emitted light, a method of manufacturing the same, and a light emitting device device using the same.

In the silicon semiconductor substrate, logic devices, arithmetic devices, and drive devices can be integrated with high reliability and high integration. Since silicon is cheap, the silicon semiconductor substrate can be realized at a much lower cost than a compound semiconductor, thereby realizing a highly integrated circuit. Therefore, most integrated circuits use silicon (Si) as a base material.

In order to fully utilize the advantages of silicon as described above, researches are being made to make silicon-based light emitting devices so that compatibility with integrated circuits and manufacturing low-cost optoelectronic devices can be realized. It has been experimentally confirmed that porous silicon and nano-crystal silicon have luminescent properties, and research on this is ongoing.

1 is a cross-sectional view of a porous silicon region formed on a bulk monocrystalline silicon surface and an energy band gap between a valence band and a conduction band in the porous silicon region.

Porous silicon can be prepared by placing bulk monocrystalline silicon (Si) in an electrolyte solution containing, for example, hydrofluoric acid (HF), and anodically electrochemically dissolving the surface of the bulk Si.

When anodizing bulk silicon in hydrofluoric acid solution, a porous silicon region 1 having a plurality of pores 1a: pore is formed on the bulk silicon surface side as shown in FIG. The Si-H bond is more present in the pore 1a portion than in the convex portion 1b: the portion not melted by hydrofluoric acid. The energy band gap between the valence band energy Ev and the conduction band energy Ec in the porous silicon region 1 is opposite to the shape of the porous silicon region 1.

Therefore, the pore portion surrounded by the convex portion in the energy band gap diagram (the convex portion 1b surrounded by the pore portion 1a in the porous silicon region 1 diagram) exhibits a quantum confinement effect, so that the energy of the bulk silicon The band gap is larger than the band gap, and electrons and holes are trapped in the portion to emit light.

For example, in the porous silicon region 1, when the convex portion 1b surrounded by the pores 1a is formed in the form of a single crystal silicon wire having a quantum confining effect, electrons and holes are trapped in the wire to emit light-coupled bonds. Depending on the size (width and length) of the wire, the emission wavelength can range from near infrared to blue. At this time, as shown in Fig. 1, the pore 1a period is, for example, approximately 5 nm, and the maximum thickness of the porous silicon region is, for example, about 3 nm.

Accordingly, when a light emitting device based on porous silicon is manufactured and a predetermined voltage is applied to the single crystal silicon on which the porous silicon region 1 is formed, light of a desired wavelength region may be emitted according to the porous characteristics.

However, the light emitting device based on the porous silicon has not yet been secured as a light emitting device, and has an external quantum efficiency (EQE) of about 0.1%.

2 is a cross-sectional view schematically showing an example of a light emitting device using nanocrystal silicon.

Referring to the drawings, a light emitting device using nanocrystal silicon includes a p-type single crystal silicon substrate 2, an amorphous silicon layer 3 formed on the substrate 2, and the amorphous silicon layer 3. The amorphous silicon layer 3 has a layer structure including an insulating film 5 formed on the upper surface and lower and upper electrodes 6 and 7 formed on the lower surface of the substrate 2 and the insulating film 5, respectively. Nanocrystalline silicon 4 in the form of a quantum dot formed therein is provided.

When the amorphous silicon layer 3 is rapidly crystallized by raising the temperature to 700 ° C. in an oxygen atmosphere, nanocrystalline silicon 4 having a quantum dot form is formed. At this time, the thickness of the amorphous silicon layer 3 is 3nm, the size of the nanocrystal silicon 4 is approximately 2 ~ 3nm.

In the light emitting device using the nanocrystal silicon 4 as described above, when the voltage is reversed through the upper and lower electrodes 7 and 6, both ends of the amorphous silicon between the silicon substrate 2 and the nanocrystal silicon 4 are provided. A large electric field is generated in the electrons and holes in the high energy state, and they are tunneled into the nanocrystal silicon 4 to emit light bonds. In this case, the light emission wavelength of the light emitting device using the nanocrystal silicon 4 becomes shorter as the size of the nanocrystal silicon quantum dot is smaller.

The light emitting device using the nanocrystal silicon 4 is difficult to control the size and uniformity of the nanocrystal silicon quantum dot, and the efficiency is very low.

The present invention has been made in order to improve the above-mentioned disadvantages, the light emitting device having a structure that is not only excellent in luminous efficiency than the light emitting device using porous silicon and nanocrystal silicon, but also can increase the intensity of the emitted light and It is an object of the present invention to provide a manufacturing method and a light emitting device apparatus using the same.

1 is a cross-sectional view of a porous silicon region formed on a bulk monocrystalline silicon surface and an energy band gap between a valence band and a conduction band in the porous silicon region;

2 is a cross-sectional view schematically showing an example of a light emitting device using nanocrystal silicon;

3 is a cross-sectional view schematically showing a light emitting device according to an embodiment of the present invention;

4A schematically shows the structure of a p-n junction when forming a doped region at an extremely shallow depth by non-equilibrium diffusion,

4B shows the energy band of a quantum well (QW) formed in the longitudinal and lateral direction of the surface at the p-n junction 14 shown in FIG. 5A by non-equilibrium diffusion,

5A to 5D illustrate a step of forming a basic light emitting device;

6 is a view illustrating a step of bonding a pair of basic light emitting devices;

7 is a view showing a step of completing the manufacture of a light emitting device according to the present invention by forming a reflective film on one doped region of the light emitting device.

<Description of the symbols for the main parts of the drawings>

11, 21 ... first and second substrates 13, 23 ... control film (silicon oxide film)

14,24 ... p-n junction 15,25 ... first and second doped region

17,27 ... first electrode 19 ... second electrode

30 ... Reflective Screen

A light emitting device according to the present invention for achieving the above object is an n-type or p-type substrate; First and second doped regions respectively formed on both sides of the substrate and doped with an extremely shallow dopant opposite to the substrate by a predetermined dopant such that light is emitted by a quantum confinement effect at a pn junction with the substrate; ; A reflection film formed on one of the first and second doped regions to reflect light emitted from the doped region toward the other doped region; And an electrode for injecting holes and electrons.

The substrate may include a first substrate and a second substrate, and the electrode may include a pair of first electrodes formed on the first and second doped regions, respectively; And a transparent second electrode formed between the first and second substrates.

A control layer may function as a mask when the first and second doped regions are formed, and the first and second doped regions may be formed to an extremely shallow doping depth.

The substrate may be formed of a predetermined semiconductor material including silicon, and the control layer may be a silicon oxide layer having an appropriate thickness such that the first and second doped regions are formed at an extremely shallow doping depth.

In the light emitting device manufacturing method according to the present invention for achieving the above object, the step of preparing an n-type or p-type substrate, the control to function as a mask for forming a doped region on the substrate and to enable extremely shallow doping Depositing a film, doping one side of the substrate with a predetermined dopant to emit light by a quantum confinement effect at a pn junction with the substrate to form an extremely shallow doped region opposite to the substrate; Forming a plurality of basic light emitting devices by forming a first electrode on a doped region and / or a second transparent electrode on an opposite surface of the substrate; Bonding a pair of basic light emitting devices having at least one transparent second electrode such that the surfaces on which the doped regions are not formed face each other; And forming a reflective film formed on one doped region of the pair of basic light emitting devices to reflect light emitted from the doped region toward the corresponding doped region.

In order to achieve the above object, the present invention provides a light emitting device comprising at least one light emitting element, the light emitting element comprising: an n-type or p-type substrate; First and second doped regions respectively formed on both sides of the substrate and doped with an extremely shallow dopant opposite to the substrate by a predetermined dopant such that light is emitted by a quantum confinement effect at a pn junction with the substrate; ; A reflection film formed on one of the first and second doped regions to reflect light emitted from the doped region toward the other doped region; An electrode for injecting holes and electrons, and is applied to an illumination system or a display system.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view schematically showing a light emitting device according to an embodiment of the present invention.

Referring to the drawings, a light emitting device according to an exemplary embodiment of the present invention may include a substrate, first and second doped regions 15 and 25 formed on both surfaces of the substrate, and on the second doped region 25. And a reflective film 30 having a high reflectance so as to completely reflect the light incident to the incident light, and an electrode for injecting holes and electrons. In addition, the light emitting device according to the present invention functions as a mask when the first and second doped regions 15 and 25 are formed, and the first and second doped regions 15 and 25 are extremely shallow ( It is preferable to further provide a control film 13 (23) to be formed to an ultra-shallow depth. The thin film layers 13 and 23 are necessary to form the first and second doped regions 15 and 25 of the light emitting device according to the present invention. The first and second doped regions 15 and 25 are necessary. It may optionally be removed after formation.

The substrate is composed of first and second substrates 11 and 21. The first and second substrates 11 and 21 may be formed of a predetermined semiconductor material including silicon (Si), for example, Si, SiC, or diamond, and doped with n-type.

The first and second doped regions 15 and 25 may diffuse a predetermined dopant such as boron or phosphorous into the substrate through the openings of the control layers 13 and 23. It is a region doped with the first and second substrates 11 and 21 oppositely to, for example, p +.

Quantum wells at the boundary portions of the first and second doped regions 15 and 25 with the first and second substrates 11 and 21, that is, at pn junction sites 14 and 24, when doped. At least one of a well, a quantum dot, and a quantum wire is formed so that the first and second doped regions 15 and 25 are extremely extreme so that light emission due to the quantum confinement effect can occur. It is preferred to be doped to a shallow depth.

In this case, a quantum well is mainly formed at the p-n junction sites 14 and 24, and a quantum dot or a quantum line may be formed. In addition, two or more of the quantum wells, the quantum dots, and the quantum lines may be formed in the p-n junction sites 14 and 24. In the following, quantum wells are formed at the p-n junction sites 14 and 24 for the sake of simplicity. Although quantum wells are formed in the p-n junction sites 14 and 24 hereinafter, they are considered to mean at least one of quantum wells, quantum dots, and quantum lines.

4A shows the structure of the p-n junction site 14 when the doped region 15 is formed to an extremely shallow depth by non-equilibrium diffusion. FIG. 4B shows the energy band of quantum wells (QW) formed longitudinally and laterally of the surface at the p-n junction site 14 shown in FIG. 4A by non-equilibrium diffusion. In FIG. 4B, Ec represents a conduction band energy level, Ev represents a valence band energy level, and Ef represents a Fermi energy level. Such energy levels are well known in the semiconductor related art, and thus detailed descriptions thereof will be omitted.

As shown in FIGS. 4A and 4B, the p-n junction site 14 has a quantum well structure in which different doping layers are alternately formed, and the wells and barriers are, for example, approximately 2 nm and 3 nm.

Here, the structure of the p-n junction site 24 and the energy band of the quantum well formed in the p-n junction site 24 are also shown as in FIGS. 4A and 4B.

As such, extremely shallow doping to form quantum wells in the p-n junction sites 14 and 24 may be formed by optimally controlling the thicknesses of the control layers 13 and 23 and the diffusion process conditions.

Due to the proper diffusion temperature during the diffusion process and the modified potential of the substrate surface, the thickness of the diffusion profile can be controlled, for example, 10-20 nm, such as in a quantum well system Will be generated. Here, the substrate surface is deformed by the thickness of the initial control film and the surface pretreatment and deepens as the process proceeds.

When the first and second substrates 11 and 21 are made of a predetermined semiconductor material including silicon, the control layers 13 and 23 may have extreme first and second doped regions 15 and 25. It is preferable that the silicon oxide film (SiO ₂ ) have an appropriate thickness to be formed with a shallow doping depth. The control films 13 and 23 form, for example, silicon oxide films on the first and second substrates 11 and 21, and then etch the opening portions for the diffusion process using a photolithography process. By forming a mask structure.

As known in the diffusion arts, if the thickness of the silicon oxide film is thicker or lower than the appropriate thickness (thousands of kPa), the vacancy mainly affects the diffusion, and the diffusion occurs deeply, and the thickness of the silicon oxide film is larger than the appropriate thickness. At thin or high temperatures, Si self-interstitial mainly affects diffusion, causing deep diffusion. Therefore, when the silicon oxide film is formed to an appropriate thickness in which Si self-interstitial and vacancy are generated at a similar rate, the Si self-interstitial and vacancy are bonded to each other and do not promote diffusion of the dopant, thereby enabling extremely shallow doping. . Here, since physical properties related to vacancy and self-interstitial are well known in the art related to diffusion, a detailed description thereof will be omitted.

Here, the first and second substrates 11 and 21 may be doped in a p-type, and the first and second doped regions 15 and 25 may be doped in an n + type.

The electrode is a second electrode formed between the first electrodes 17 and 27 formed on the first and second doped regions 15 and 25, respectively, and the first and second substrates 11 and 21. It is preferable that it consists of (19). The second electrode 19 is preferably made of a transparent electrode for transmitting light, for example, ITO.

In the light emitting device according to the exemplary embodiment of the present invention configured as described above, the pn junction portions 14 and 24 are applied by applying power (current) to the first electrodes 17 and 27 and the second electrode 19. Since the quantum wells in which the evanescent coupling of the electrons and hole pairs injected into the pn may occur are formed at the pn junction sites 14 and 24, light of an arbitrary or specific wavelength is emitted by the quantum confinement effect. The amount of light emitted and the wavelength depend on the amount of current applied. At this time, since the reflective film 30 formed on the lower surface of the second doped region 25 reflects the light generated in the downward direction of the light emitting device toward the first doped region 15, the light having a large intensity is applied to the first doped region ( 15 is emitted through the window 31 on. Here, the light incident on the reflective film 30 is a portion of the light generated at the pn junction regions 14 and 24 of the second doped region 25 and the pn junction region 14 of the first doped region 15. Light generated at 24 and traveling toward the second doped region 25.

The light emitting device according to the present invention as described above can be applied to the display system or the lighting system as a light emitting device device, when applied to the display system or the lighting system can obtain a larger amount of light emission than when applying a conventional light emitting device. In this case, the light emitting device device includes at least one light emitting device according to the present invention. In the case of a display system, the light emitting device device comprises a plurality of light emitting elements according to the invention arranged in two dimensions. Since the light emitting device according to the present invention can be formed into a microminiature through a semiconductor manufacturing process using a semiconductor material, it is obvious that it can be applied to a display system, in particular, a flat panel solid state display. In the case of a lighting system, the light emitting device device comprises at least one light emitting element according to the invention in response to the use of the lighting system and the illuminance requirement. As described above, the structure of the light emitting device device to which the light emitting element according to the present invention is applied can be sufficiently inferred through the above description, and thus, detailed description and illustration are omitted.

Hereinafter, a preferred embodiment of a method of manufacturing a light emitting device according to the present invention having a structure as shown in FIG.

5A to 5D illustrate a step of forming a basic light emitting device, FIG. 6 illustrates a step of bonding a pair of basic light emitting devices, and FIG. 7 forms a reflective film 30 on one doped region of the light emitting device. To show the step of completing the manufacturing of the light emitting device according to the present invention.

In order to manufacture the light emitting device according to the present invention, first, as shown in FIG. 5A, a substrate 11 including n-type or p-type silicon, for example, an Si-type doped with n-type is prepared.

On the prepared substrate 11, as shown in Fig. 5B, a desired thin thickness control film 13 having an opening, for example, a silicon oxide film, is deposited. This silicon oxide film is formed to an appropriate thickness to function as a mask and to allow extremely shallow doping during the doping for forming the doped region.

Next, as shown in FIG. 5C, the dopant such as boron or phosphorus is opposite to the substrate 11 by non-equilibrium diffusion which diffuses from the surface exposed to the opening into the substrate 11 at an appropriate diffusion temperature. For example, the p + type doped region 15 is formed.

Next, as shown in FIG. 5D, the first electrode 17 is formed on the doped region 13 side of the substrate 11, and the transparent second electrode 19 is formed on the opposite side of the substrate 11 to complete the basic light emitting device. do. The first electrode 17 is formed in a region excluding the window 31 from which light on the doped region 15 is emitted.

In FIG. 5A to FIG. 5D, the same reference numerals are used as in FIG. 3 in order to avoid unnecessarily repeatedly explaining the members constituting the light emitting device, the materials constituting the members, and the physical functions thereof. 5A to 5D illustrate one basic light emitting device including the first substrate 11 and the first doped region 15, and the manufacturing process is substantially the second substrate 21 and the second doping. The same applies to other basic light emitting elements including the region 25. One basic light emitting device and the other basic light emitting device as described above may be produced in a batch during the same manufacturing process, or may be manufactured through different manufacturing processes.

Based on FIG. 5D and the foregoing description, each pair of basic light emitting devices has a transparent second electrode 19, and each pair of basic light emitting devices must have a transparent second electrode 19. There is no need to do it. That is, it is also possible to form the transparent second electrode 19 only on one side of the pair of basic light emitting elements forming the light emitting element according to the present invention by joining correspondingly. Since the basic light emitting device as described above can be mass-produced on one large substrate through a semiconductor process, the array structure forms a basic light emitting device having a structure required for one large substrate, cuts them appropriately, and then bonds them together. The light emitting device according to the present invention may be formed, or a basic light emitting device may be formed in a structure required for different large substrates, and these may be bonded to each other.

Next, as shown in FIG. 6, a pair of basic light emitting devices completed through the manufacturing process as described above are bonded to face each other without the doped regions 15 and 25 formed thereon. Bonding can be done using an adhesive. It is preferable to use a conductive adhesive as the adhesive. In particular, when the transparent second electrode 19 is formed on only one of the paired basic light emitting devices, the second electrode 19 is formed of the first and second substrates. It is necessary to use a conductive adhesive as the adhesive so as to be electrically connected to all of 11) (21).

Finally, as shown in FIG. 7, the reflective film 30 having a high reflectance is formed on the second doped region 25. Here, the reflective film 30 may be first formed on the second doped region 25, and then a pair of basic light emitting devices may be bonded to each other.

As described above, the light emitting device according to the present invention has a doped region which is extremely shallowly doped to increase the intensity of emitted light and emits light due to quantum confinement effect at its pn junction, thereby providing porous silicon and nanocrystals. The light emitting efficiency is higher than that of the light emitting device using silicon. In addition, since the doped regions are formed on both sides and a reflective film is formed on one doped region, the intensity of the emitted light can be greatly increased.

Claims (10)

an n-type or p-type substrate; First and second doped regions respectively formed on both sides of the substrate and doped with an extremely shallow dopant opposite to the substrate by a predetermined dopant such that light is emitted by a quantum confinement effect at a pn junction with the substrate; ; A reflection film formed on one of the first and second doped regions to reflect light emitted from the doped region toward the other doped region; Light emitting device comprising a; electrode for injecting holes and electrons. The method of claim 1, wherein the substrate is composed of a first and a second substrate, The electrode, A pair of first electrodes formed on the first and second doped regions, respectively; And a transparent second electrode formed between the first and second substrates. The method according to claim 1 or 2, And a control layer which functions as a mask when the first and second doped regions are formed, and wherein the first and second doped regions are formed to an extremely shallow doping depth. The method of claim 3, wherein the substrate is made of a predetermined semiconductor material including silicon, The control film is a light emitting device, characterized in that the silicon oxide film having a suitable thickness so that the first and second doped region is formed to an extremely shallow doping depth. preparing an n-type or p-type substrate, depositing a control film that functions as a mask for forming a doped region on the substrate and enables extremely shallow doping, and has a quantum confinement effect at a pn junction with the substrate Doping one side of the substrate with a predetermined dopant so as to cause light emission to form an extremely shallow doped region opposite to the substrate, the first electrode on the doped region and / or transparent to the opposite side of the substrate Forming a plurality of basic light emitting elements by forming a second electrode; Bonding a pair of basic light emitting devices having at least one transparent second electrode such that the surfaces on which the doped regions are not formed face each other; And forming a reflective film formed on one doped region of the pair of basic light emitting elements to reflect the light emitted from the doped region toward the corresponding doped region. The method of claim 5, wherein the substrate is made of a predetermined semiconductor material including silicon, And the control film is a silicon oxide film having an appropriate thickness such that the first and second doped regions are formed with an extremely shallow doping depth. A light emitting device device comprising at least one light emitting element, The light emitting device, an n-type or p-type substrate; First and second doped regions respectively formed on both sides of the substrate and doped with an extremely shallow dopant opposite to the substrate by a predetermined dopant such that light is emitted by a quantum confinement effect at a pn junction with the substrate; ; A reflection film formed on one of the first and second doped regions to reflect light emitted from the doped region toward the other doped region; And an electrode for injecting holes and electrons, wherein the light emitting device device is applied to an illumination system or a display system. The method of claim 7, wherein the substrate is composed of a first and a second substrate, The electrode, First electrodes formed on the first and second doped regions, respectively; And a transparent second electrode formed between the first and second substrates. The method according to claim 7 or 8, The light emitting device may further include a control layer that functions as a mask when the first and second doped regions are formed, and allows the first and second doped regions to be formed with an extremely shallow doping depth. Light emitting device device. The method of claim 9, wherein the substrate is made of a predetermined semiconductor material including silicon, And the control film is a silicon oxide film having an appropriate thickness such that the first and second doped regions are formed with an extremely shallow doping depth.