KR100719915B1 - light emitting devices and manufacturing method thereof using ZnO - Google Patents

Abstract

The present invention relates to a short wavelength light emitting device using zinc oxide and a method of manufacturing the same. A short wavelength light emitting device using zinc oxide according to the present invention includes a base substrate; An n-type zinc oxide layer deposited on the base substrate; A well structure layer formed on top of the n-type zinc oxide layer and including zinc oxide, the barrier layer having a large band gap, the well layer having a small band gap, and the barrier layer having a large band gap sequentially deposited; A p-type zinc oxide layer deposited on the well structure layer; A first metal electrode formed on the base substrate or the n-type zinc oxide layer; And a second metal electrode formed on the p-type zinc oxide layer.

Short wavelength, zinc oxide, light emitting element, diode, sputter

Description

Light emitting devices and manufacturing method using zinc oxide

1 is a cross-sectional view of a short wavelength light emitting device using zinc oxide according to an embodiment of the present invention;

2 is a cross-sectional view of a short wavelength light emitting device using zinc oxide according to another embodiment of the present invention;

3 is a flowchart illustrating a process of manufacturing a short wavelength light emitting device using zinc oxide of FIG. 2;

4 is a graph showing a change in current value according to the voltage of the short wavelength light emitting device manufactured according to the present invention;

Fig. 5 is a graph showing the emission spectrum of the short wavelength light emitting device produced by this invention.

     <Brief description of symbols for the main parts of the drawings>

11, 21; A base substrate 22; n-type zinc oxide layer

12, 14, 23, 25; Barrier layers 13, 24; Well layer

15, 26; p-type zinc oxide layers 16, 17, 27, 28; Metal electrode

The present invention relates to a method for manufacturing a short wavelength light emitting device using zinc oxide.

Light emitting diodes (LEDs) and laser diodes (LDs), which emit light spontaneously under forward bias conditions, have been of great importance in the field of visual display, optical data storage and optical fiber communication. Recently, as information usage in the field of information and communication expands exponentially, optical devices in a short wavelength region are required to store a larger amount of information. In addition, as interest in light sources with low energy consumption and high light efficiency increases, interest in light emitting diodes (LEDs) is gradually increasing. That is, there is a demand for development of light emitting diodes (LEDs) that gradually emit light in a short wavelength region.

Until now, gallium nitride (GaN) semiconductors have been used for the technology related to shorter wavelengths of light emitting diodes. As a result of short wavelength, green and blue LEDs using p-type gallium nitride (GaN) semiconductors have been developed and used.

However, these gallium nitride-based semiconductors have disadvantages of difficulty of crystal growth and high device resistance that are made at high temperature (1000 ° C. or higher). In particular, in the case of a p-type gallium nitride-based semiconductor, since the surface of the thin film is not good and the carrier density is low, it is difficult to manufacture a gallium nitride-based semiconductor device. For this reason, there is no progress in the development of light emitting devices in the short wavelength region using gallium nitride based semiconductors.

The industry has made an effort to find a new short wavelength light emitting material to replace gallium nitride, and zinc oxide (ZnO) is attracting attention as a representative material to replace gallium nitride. The reason is that zinc oxide has a very similar crystal structure and band gap with gallium nitride, but has an exciton binding energy about three times higher than gallium nitride, and can produce high quality thin films at relatively low temperatures.

However, despite these advantages of zinc oxide, it is very difficult to produce a p-type zinc oxide thin film, and its electrical characteristics are also very unstable. For example, there has been a report that a p-type zinc oxide thin film was developed using arsenic (As) and nitrogen (N), but its reproducibility is very low and cannot be utilized. In addition, there have been reports of zinc oxide p-n junctions produced, but the electrical properties, optical properties, and efficiency are very poor and thus are not manufactured as actual devices. Due to the difficulty in manufacturing the p-type zinc oxide thin film, an attempt has been made to develop a heterojunction light emitting device by growing an n-type zinc oxide thin film on a p-type gallium nitride or p-type strontium oxide thin film instead of the p-type zinc oxide. .

Looking at the prior art to develop a p-type zinc oxide and to develop a light emitting device using the p-type zinc oxide thin film, U.S. Patent No. 6410162 describes arsenic (As) as a p-type by MBE (molecular beam epitaxy) method. A method of use as a dopant is disclosed. However, in this method, the leakage current due to the defects of the thin films is so large that the electrical characteristics of the optical device are close to the ohmic characteristics, the manufacturing time is long, and it is uneconomical with expensive equipment, and the large-area growth of the thin film is difficult. There is this.

In addition, Korean Patent Publication No. 2001-70677, 'Method of manufacturing short wavelength zinc oxide light emitting device according to deposition temperature' and Korean Patent Publication No. 2001-68017, 'Method of manufacturing short wavelength zinc oxide light emitting device by post heat treatment' Although a zinc oxide (sapphire) substrate, which is an insulator, is used as a p-type semiconductor, no method of manufacturing the same is presented.

In addition, Korean Patent Publication No. 2002-48377, 'ZnO-based compound semiconductor light emitting device and its manufacturing method' discloses a high quality zinc oxide thin film growth method and a structure of the light emitting device, but a method of manufacturing a p-type zinc oxide thin film There is no mention at all, and no optical or electrical characteristics of the zinc oxide light emitting device are given.

However, as a technique for developing a p-type zinc oxide thin film using sputtering in 2003 was published in the Applied Physics Letters, research on zinc oxide light emitting devices using the same has been accelerated. However, until now, no p-type zinc oxide light emitting device having reproducibility and reliability and a method of manufacturing the same have been proposed.

An object of the present invention is to grow a single or multiple well structure consisting of a barrier layer and a well layer between a p-type zinc oxide layer and an n-type zinc oxide layer, thereby providing a short wavelength light emitting device using zinc oxide having stable electrical and optical properties. To provide a method for producing a.

Short wavelength light-emitting device using zinc oxide according to the present invention for achieving the above object, a base substrate; A well structure layer disposed on the base substrate and including zinc oxide, the barrier layer having a large band gap, the well layer having a small band gap, and the barrier layer having a large band gap sequentially deposited; A p-type zinc oxide layer deposited on the well structure layer; And a metal electrode formed on the base substrate and the p-type zinc oxide layer, respectively.

In addition, the short wavelength light-emitting device using zinc oxide according to the present invention includes a base substrate; An n-type zinc oxide layer deposited on the base substrate; A well structure layer formed on top of the n-type zinc oxide layer and including zinc oxide, the barrier layer having a large band gap, the well layer having a small band gap, and the barrier layer having a large band gap sequentially deposited; A p-type zinc oxide layer deposited on the well structure layer; A first metal electrode formed on the base substrate or the n-type zinc oxide layer; And a second metal electrode formed on the p-type zinc oxide layer.

In addition, the method for manufacturing a short wavelength light emitting device using zinc oxide according to the present invention includes zinc oxide on the base substrate, and includes a barrier layer having a large band gap, a well layer having a small band gap, and a well having a large band gap barrier layer. A well structure layer deposition step of depositing a structure layer; A p-type zinc oxide layer deposition step of depositing a p-type zinc oxide layer on the well structure layer; A heat treatment step of activating the p-type zinc oxide layer by heat treatment; And forming a metal electrode on the base substrate and the p-type zinc oxide layer, respectively.

In addition, the method for manufacturing a short wavelength light emitting device using zinc oxide according to the present invention includes an n-type zinc oxide layer deposition step of depositing an n-type zinc oxide layer on the base substrate; Depositing a well structure layer including zinc oxide on the n-type zinc oxide layer, and depositing a well structure layer including a barrier layer having a large band gap, a well layer having a small band gap, and a barrier layer having a large band gap; A p-type zinc oxide layer deposition step of depositing a p-type zinc oxide layer on the well structure layer; A heat treatment step of activating the p-type zinc oxide layer by heat treatment; And forming a metal electrode on the base substrate or the n-type zinc oxide layer and the p-type zinc oxide layer, respectively.

Hereinafter, a method of manufacturing a short wavelength light emitting device using zinc oxide according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a short wavelength light emitting device using zinc oxide according to an embodiment of the present invention. The short wavelength light emitting device using zinc oxide includes a base substrate 11, a barrier layer 12, a well layer 13, a barrier layer 14, and a barrier layer 14 sequentially deposited on the base substrate 11. The p-type zinc oxide layer 15 deposited thereon and the metal electrodes 16 and 17 formed on the base substrate 11 and the p-type zinc oxide layer 15, respectively.

2 is a cross-sectional view of a short wavelength light emitting device using zinc oxide according to another exemplary embodiment of the present invention. The short wavelength light emitting device using zinc oxide includes a base substrate 21, an n-type zinc oxide layer 22 deposited on the base substrate 21, and a barrier layer sequentially deposited on the n-type zinc oxide layer 22 ( 23, the well layer 24, the barrier layer 25, the p-type zinc oxide layer 26 deposited on the barrier layer 25, the n-type zinc oxide layer 22 and the p-type zinc oxide layer 26 Metal electrodes 27 and 28 respectively formed on the upper side.

Here, the base substrates 11 and 21 are made of one element or two or more compounds of aluminum oxide (sapphire), silicon (Si), gallium arsenide (GaAs), silicon carbide (SiC), and zinc oxide (ZnO). Is done. The dopant material used for depositing the n-type zinc oxide layer 22 is made of a compound including one element of aluminum (Al), gallium (Ga), indium (In), or two or more elements.

The barrier layers 12, 14, 23, and 25 are zinc oxide thin films having a large band gap, and the barrier layers 12, 14, 23, and 25 include zinc oxide and a dopant material that increases the band gap. . The dopant material which enlarges this band gap consists of a compound containing one element or two or more elements of lithium (Li), sodium (Na), beryllium (Be), and magnesium (Mg).

The well layers 13 and 24 are thin zinc oxide thin films, and the well layers 13 and 24 are made of pure zinc oxide layers, or include zinc oxide and a dopant material having a small band gap. The dopant material for reducing the band gap is one element of calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), cadmium (Cd), or mercury (Hg). It consists of a compound containing more than one element.

In addition, the dopant materials used for depositing the p-type zinc oxide layers 15 and 26 are phosphorus (P), nitrogen (N), rhenium (Re), lithium (Li), sodium (Na), potassium (K), Cesium (Cs), antimony (Sb), lead (Pb), arsenic (As), copper (Cu) may be composed of one element or a compound containing two or more elements. In addition, the dopant material used for depositing the p-type zinc oxide layers 15 and 26 is one or two or more elements of phosphorus (P), nitrogen (N), antimony (Sb), and arsenic (As). And a compound containing boron (B), aluminum (Al), gallium (Ga), indium (In), and one or more of two elements.

The above-described barrier layer / well layer / barrier layer constitutes a well structure layer, and this well structure layer may be formed in a single or multiple.

When a voltage is applied in the forward direction to the short wavelength light emitting device configured as described above, the short wavelength light emitting device emits light. That is, when + bias is applied to the metal electrode bonded to the p-type zinc oxide layer and − bias is applied to the metal electrode bonded to the n-type zinc oxide layer (or base substrate), electrons of the n-type zinc oxide layer (or base substrate) are applied. Is diffused into the p-type zinc oxide layer and holes of the p-type zinc oxide layer diffuse into the n-type zinc oxide layer (or base substrate), and the junction surface of the p-type zinc oxide layer and the n-type zinc oxide layer (or base substrate) In the electron and hole are combined, the short wavelength light emitting device emits light by the binding energy. At this time, electrons and holes are trapped in the well layer by the barrier layer located between the p-type zinc oxide layer and the n-type zinc oxide layer (or base substrate), thereby improving the light efficiency.

3 is a flowchart illustrating a process of manufacturing a short wavelength light emitting device using zinc oxide of FIG. 2.

First, an n-type zinc oxide thin film is grown on a base substrate at a thickness of about 0.5 to 2 μm at 200 to 1000 ° C. (S31). A barrier layer having a thickness of about 0.3 to 20 μm, a well layer having a thickness of about 0.3 to 20 μm, and a barrier layer having a thickness of about 0.3 to 20 μm are sequentially grown thereon at 200 to 1000 ° C. (S32). The p-type zinc oxide thin film is grown thereon at a thickness of about 0.3 to 20 μm at 200 to 1000 ° C. (S33). Thereafter, heat treatment is performed at a temperature of 300 to 1000 ° C. for 1 to 3 minutes in an atmosphere containing nitrogen, oxygen, at least one element in the atmosphere or at least two elements (S34), and the n-type zinc oxide layer and the p-type zinc oxide Metal electrodes are formed on the layers (S35). At this time, the p-type zinc oxide thin film is produced by the sputtering method.

In the above-described embodiment of FIG. 3, step S31 is omitted, and instead of forming a metal electrode on the n-type zinc oxide layer and the p-type zinc oxide layer in the metal electrode deposition step (S35), on the base substrate and the p-type zinc oxide layer When the metal electrode is formed, a short wavelength light emitting device using zinc oxide of FIG. 1 may be manufactured.

4 is a graph showing a change in current value according to the voltage of the short wavelength light emitting device manufactured according to the present invention, and shows typical diode characteristics.

Fig. 5 is a graph showing the emission spectrum of the short wavelength light emitting device manufactured by this invention, showing short wavelength characteristics.

Hereinafter, an application example of the short wavelength light emitting device using zinc oxide of the present invention will be described.

[Application Example]

The pressure inside the sputter chamber is 10mTorr ~ 20mTorr, and the ratio of argon and oxygen is 1: 1 ~ 3: 1 while maintaining the temperature of the base substrate at 200 ~ 1200 ℃ and then supplying AC power 60 ~ 150Ｗ and n type A zinc oxide thin film is deposited. At this time, if the AC power is not sufficiently supplied or if too much power is supplied, it is impossible to form a thin film of good quality. The target used for making the n-type zinc oxide thin film is a mixture of zinc oxide and Al ₂ O ₃ or Ga ₂ O ₃ or In ₂ O ₃ in a mass ratio of 97: 3 to 99.9: 0.1. The higher the mass ratio of the dopant material, the worse the characteristics of the thin film. However, if the amount is smaller than the amount, the amount of the dopant is not sufficiently supplied.

The target used to make the zinc oxide thin film having a large band gap corresponding to the barrier layer is a mixture of zinc oxide and Li ₂ O or Na ₂ O or BeO or MgO at a mass ratio of 50:50 to 99.9: 0.1. . The higher the mass ratio of the dopant material, the worse the characteristics of the thin film. However, if the amount is less than the amount of the dopant, the amount of the dopant is not sufficiently supplied, and thus the band gap is not controlled.

The target used to make the zinc oxide thin film having a small band gap corresponding to the well layer is a mixture of zinc oxide and CaO or SrO or BaO or RaO or CdO or HgO at a mass ratio of 50:50 to 99.9: 0.1. . The higher the mass ratio of the dopant material, the worse the characteristics of the thin film. However, if the amount is less than the amount of the dopant, the amount of the dopant is not sufficiently supplied, and thus the band gap is not controlled.

Next, a zinc oxide layer doped with phosphorus (P) doped with a p-type dopant is deposited on the barrier layer while maintaining a constant pressure inside the sputter reactor, maintaining an AC power of 60 to 150 kPa, and maintaining a temperature between 200 to 1000 ° C. . The target used to make the zinc oxide thin film doped with phosphorus (P) is a mass ratio of zinc oxide and P ₂ O ₅ or P or Zn ₂ P ₂ O ₇ or Zn ₃ P ₂ in a ratio of 97: 3 to 99.9: 0.1. Use a mixture of.

The resultant of depositing the zinc oxide layer doped with phosphorus (P) is heat-treated for 1 to 3 minutes at a temperature of 300 ~ 1000 ℃ in nitrogen and air atmosphere. As a result, the zinc oxide thin film doped with phosphorus (P) becomes electrically p-type due to activation of phosphorus (P), a p-type dopant, thereby completing a p-type zinc oxide layer. The concentration of holes in this p-type zinc oxide layer is about 1 × 10 ¹⁸ to 1.7 × 10 ¹⁹ cm ^-3 , and the mobility of holes is about 0.5 to 3.5 cm ² / Vs.

The concentration of electrons in the n-type zinc oxide layer is about 1 × 10 ¹⁸ to 1 × 10 ²¹ cm ^-3 , and the mobility of electrons is about 1 to 100 cm ² / Vs. When the heat treatment process is performed, the crystallinity of the thin film is also greatly improved, thereby reducing the non-emitting central defects, and the light efficiency of the light emitting device is increased because the charge is constrained by the combination of the zinc oxide thin film and the doped zinc oxide layer having a small band gap.

Although the technical spirit of the present invention has been described above with the accompanying drawings, it is intended to exemplarily describe the best embodiment of the present invention, but not to limit the present invention. In addition, it is obvious that any person skilled in the art may make various modifications and imitations without departing from the scope of the technical idea of the present invention.

According to the present invention as described above, there is an advantage that a short wavelength light emitting device having a long operation time, stable electrical characteristics and excellent light efficiency can be manufactured.

Claims (22)

delete delete delete delete delete delete delete delete delete delete delete delete N-type zinc oxide layer deposition step of depositing an n-type zinc oxide layer having a thickness of 0.5 ~ 2㎛ on the single crystal base substrate; Depositing a well structure layer including zinc oxide on the n-type zinc oxide layer, and depositing a well structure layer including a barrier layer having a large band gap, a well layer having a small band gap, and a barrier layer having a large band gap; A p-type zinc oxide layer deposition step of depositing a zinc oxide layer doped with a p-type dopant on the well structure layer; P-type zinc oxide layer activation step of activating the p-type dopant by heat-treating the zinc oxide layer doped with the p-type dopant; And a metal electrode forming step of forming metal electrodes on the base substrate or the n-type zinc oxide layer and the p-type zinc oxide layer, respectively. The method of claim 13, wherein the depositing of the well structure layer comprises forming the well structure layer in multiple layers. The method of claim 13, wherein the base substrate is made of one element or two or more compounds of aluminum oxide (sapphire), silicon (Si), gallium arsenide (GaAs), silicon carbide (SiC), and zinc oxide (ZnO). A short wavelength light emitting device manufacturing method using zinc oxide, characterized in that made. The n-type zinc oxide layer comprises zinc oxide and an n-type dopant material, wherein the n-type dopant material is one of aluminum (Al), gallium (Ga), and indium (In). A method for manufacturing a short wavelength light emitting device using zinc oxide, characterized in that the element or a compound containing two or more elements. The method of claim 13, wherein the barrier layer comprises zinc oxide and a dopant material that enlarges the band gap, and the dopant material that enlarges the band gap includes lithium (Li), sodium (Na), beryllium (Be), A method for manufacturing a short wavelength light emitting device using zinc oxide, characterized in that the compound consists of one element or two or more elements of magnesium (Mg). The method of claim 13, wherein the well layer is formed of zinc oxide. 19. The method of claim 18, wherein the well layer further comprises a dopant material for reducing the band gap, wherein the dopant material for reducing the band gap is calcium (Ca), strontium (Sr), barium (Ba) , Radical (Ra), cadmium (Cd), mercury (Hg) of one element or a compound comprising a compound containing two or more elements of a short wavelength light emitting device using a zinc oxide, characterized in that. The method of claim 13, wherein the p-type zinc oxide layer comprises zinc oxide and a p-type dopant material, wherein the p-type dopant material is phosphorus (P), nitrogen (N), rhenium (Re), or lithium (Li). ), Compound containing one or more elements of sodium (Na), potassium (K), cesium (Cs), antimony (Sb), lead (Pb), arsenic (As), copper (Cu) Short wavelength light emitting device manufacturing method using zinc oxide, characterized in that consisting of. The method of claim 13, wherein the p-type zinc oxide layer comprises zinc oxide and p-type dopant material, the p-type dopant material is phosphorus (P), nitrogen (N), antimony (Sb), arsenic ( One element or two or more elements of As) and one or two or more elements of boron (B), aluminum (Al), gallium (Ga), indium (In), and thalilium (Tl) A short wavelength light emitting device manufacturing method using zinc oxide, characterized in that consisting of a compound containing them together. The method of claim 13, wherein the p-type zinc oxide layer activating step, heat treatment for 1 to 3 minutes at a temperature of 300 ~ 1000 ℃ in an atmosphere containing one element or two or more elements of nitrogen, oxygen, air. A method for manufacturing a short wavelength light emitting device using zinc oxide.

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