CN110993759B - Ultraviolet light emitting device using composite electron blocking layer and preparation method thereof - Google Patents

Abstract

The invention provides an ultraviolet light-emitting device adopting a composite electron blocking layer and a preparation method thereof, and relates to the technical field of semiconductors. The ultraviolet light-emitting device comprises a substrate, a low-temperature buffer layer, a high-temperature layer, an N-type Al _mGa_1‑m N layer, a light-emitting active region, a p-type composite electron blocking layer, a p-type Al _nGa_1‑n N layer and a contact layer which are sequentially grown on the substrate; the p-type composite electron blocking layer comprises a p-type L1 layer and a p-type L2 layer which are sequentially formed along the growth direction. The ultraviolet light-emitting device can effectively increase electron limiting effect, enhance hole injection efficiency and current expansion capability during carrier injection, thereby improving the radiation recombination rate of the ultraviolet light-emitting device in a quantum well and improving the light-emitting efficiency of the device.

Description

Ultraviolet light emitting device using composite electron blocking layer and preparation method thereof

Technical Field

The invention relates to the field of semiconductor technology, and in particular to an ultraviolet light-emitting device using a composite electron blocking layer and a preparation method thereof.

Background technique

Because UV LEDs are environmentally friendly, non-toxic, low power consumption, small size and long life, they meet the requirements of environmental protection and energy saving. They have important application value in the fields of UV curing, air and water purification, biomedicine, high-density storage, security and confidentiality communications, etc.

At present, the primary problem facing UV LED technology is its low light efficiency. The output power of UV LEDs with a wavelength of 365nm is only 5%-8% of the input power. The photoelectric conversion efficiency of UV LEDs with a wavelength of more than 385nm is significantly improved compared to those with shorter wavelengths, but the output power is only 15% of the input power. How to effectively improve the light efficiency of UV LEDs has become a focus of attention.

Therefore, designing an ultraviolet light-emitting device and its preparation method can effectively increase the electron confinement effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, thereby increasing the radiation recombination rate of the ultraviolet light-emitting diode in the quantum well and improving the luminescence efficiency of the device. This is a technical problem that urgently needs to be solved.

Summary of the invention

The object of the present invention is to provide an ultraviolet light-emitting device using a composite electron blocking layer and a preparation method thereof, which can effectively increase the electron confinement effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, thereby increasing the radiation recombination rate of the ultraviolet light-emitting diode in the quantum well and improving the luminous efficiency of the device.

In a first aspect, the present invention provides a technical solution:

An ultraviolet light-emitting device using a composite electron blocking layer comprises a substrate and a low-temperature buffer layer, a high-temperature layer, an n-type Al _m Ga _1-m N layer, a light-emitting active region, a p-type composite electron blocking layer, a p-type Al _n Ga _1-n N layer and a contact layer sequentially grown on the substrate; wherein the p-type composite electron blocking layer comprises a p-type L1 layer and a p-type L2 layer sequentially formed along a growth direction.

In a preferred embodiment of the present invention, the p-type L1 layer is formed of p-AlInGaN, and the p-type L2 layer is formed of p-AlGaN/AlInGaN superlattice.

In a preferred embodiment of the present invention, the p-type L1 layer is formed of p-AlInGaN, and the p-type L2 layer is formed of p-AlGaN.

In a preferred embodiment of the present invention, the p-type L1 layer is formed of p-AlGaN, and the p-type L2 layer is formed of p-AlGaN/AlInGaN superlattice.

In a preferred embodiment of the present invention, the p-type L1 layer is formed of p-AlGaN, and the p-type L2 layer is formed of p-AlInGaN.

In a preferred embodiment of the present invention, the thickness of the p-type L1 layer is in the range of 5 nm to 30 nm, and the thickness of the p-type L2 layer is in the range of 5 nm to 30 nm.

In a preferred embodiment of the present invention, the Al composition value and the In composition value of the p-AlGaN or p-AlInGaN in the p-type L1 layer and the p-type L2 layer are fixed or linearly gradient in their respective single layers.

In a preferred embodiment of the present invention, the light emitting active region is formed by alternating growth of quantum well layers and quantum barrier layers.

In a preferred embodiment of the present invention, the Al composition value in the p-type L1 layer and the Al composition value in the p-type L2 layer are both greater than the Al composition value in the quantum barrier layer.

In a preferred embodiment of the present invention, the In composition value in the p-type L1 layer and the In composition value in the p-type L2 layer are both greater than the In composition value in the quantum well layer.

In a second aspect, the present invention provides a technical solution:

A method for preparing an ultraviolet light-emitting device using a composite electron blocking layer comprises: a low-temperature buffer layer, a high-temperature layer, an n-type Al _m Ga _1-m N layer, a light-emitting active region, a p-type composite electron blocking layer, a p-type Al _n Ga _1-n N layer and a contact layer grown sequentially on the substrate; wherein the p-type composite electron blocking layer comprises a p-type L1 layer and a p-type L2 layer sequentially formed along the growth direction.

The beneficial effects of the ultraviolet light-emitting device using a composite electron blocking layer and the preparation method thereof provided by the present invention are:

Introducing a p-type composite electron blocking layer in the ultraviolet light-emitting device, the main function of the p-type L1 layer is to match the lattice of the quantum well layer and adjust the energy band of the last quantum barrier layer, effectively reducing the electron leakage in the quantum well layer. The main function of the p-type L2 layer is to improve the electron blocking effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, so that the carriers can be more effectively and evenly injected into the light-emitting active area of the device for radiation recombination, thereby improving the light efficiency of the ultraviolet light-emitting device.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

FIG1 is a schematic structural diagram of an ultraviolet light emitting device provided in a first embodiment of the present invention.

FIG. 2 is a flow chart of a method for preparing an ultraviolet light-emitting device provided in a fifth embodiment of the present invention.

3 and 4 are schematic diagrams of the structure of the ultraviolet light emitting device preparation process.

Icon: 100-ultraviolet light-emitting device; 110-substrate; 120-low-temperature buffer layer; 130-high-temperature layer; 140-n-type Al _m Ga _1-m N layer; 150-light-emitting active region; 160-p-type composite electron blocking layer; 161-p-type L1 layer; 162-p-type L2 layer; 170-p-type Al _n Ga _1-n N layer; 180-contact layer.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition and explanation in the subsequent drawings.

In the description of the present invention, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

A key factor limiting the light efficiency of ultraviolet light-emitting diodes is insufficient hole injection and electron leakage. Because the activation energy of Mg in GaN is about 200meV, and the activation energy in p-AlGaN with a high Al content is higher (reaching 630meV in AlN), the concentration of holes that can be thermally activated is lower, causing a serious lack of hole injection, resulting in a large number of electrons leaking from the active region to the p-type region and being lost; the activation energy of Si in GaN is only 15meV, and it is as high as 282meV in AlN.

Whether it is N-type doping or P-type doping, the doping efficiency of impurities in wide bandgap AlGaN is very low. For ultraviolet light-emitting diodes grown on polar surfaces, the polarization effect will further aggravate the leakage of electron current. These leaked electrons cannot emit light effectively, and their energy can only be dissipated in the form of heat.

In order to reduce the leakage of electron current, an electron blocking layer (EBL) is introduced after the last quantum barrier (LQB) in the device structure, and the conduction band step of the LQB/EBL interface is used to block the electron leakage. Generally, blue light emitting diodes usually use GaN as LQB and AlGaN as EBL; ultraviolet light emitting diodes usually use AlGaN with a constant Al component as LQB and AlGaN with a higher Al component as EBL. However, the structure obtained in this way will cause the valence band to move up, forming a potential barrier for holes, making hole injection more insufficient, which is not conducive to radiative recombination. At the same time, the insufficient hole injection will induce greater electron leakage. Therefore, how to effectively improve the carrier injection efficiency of ultraviolet semiconductor light emitting diodes directly affects the improvement of their internal quantum efficiency and luminous efficiency.

The following embodiments of the present invention provide an ultraviolet light-emitting device using a composite electron blocking layer and a preparation method thereof. The composite electron blocking layer structure is introduced into the ultraviolet light-emitting diode to optimize the energy band structure of the device, which can effectively increase the electron confinement effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, thereby increasing the radiation recombination rate of the ultraviolet light-emitting diode in the quantum well and improving the luminous efficiency of the device.

First embodiment

Referring to FIG. 1 , this embodiment provides an ultraviolet light-emitting device 100 using a composite electron blocking layer, wherein the ultraviolet light-emitting device 100 includes a substrate 110 and a low-temperature buffer layer 120 , a high-temperature layer 130 , an n-type Al _m Ga _1-m N layer 140 , a light-emitting active region 150 , a p-type composite electron blocking layer 160 , a p-type Al _n Ga _1-n N layer 170 and a contact layer 180 sequentially grown on the substrate 110 .

The light emitting active region 150 includes _{InxGa1 -xN} and _{AlyGa1 -yN} , 0.001≤x<y≤1. The light emitting active region 150 is formed by alternating growth of quantum well layers and quantum barrier layers. The thickness of the quantum well layers ranges from 1.5nm to 10nm, and the thickness of the quantum barrier layers ranges from 4nm to 20nm.

The p-type composite electron blocking layer 160 includes a p-type L1 layer 161 and a p-type L2 layer 162 sequentially formed along the growth direction. The p-type L1 layer 161 is formed of p-AlInGaN, and the thickness of the p-type L1 layer 161 ranges from 5nm to 30nm. The Al component value in the p-type L1 layer 161 may exceed the Al component value in the quantum barrier layer, or may exceed the Al component value in the quantum well layer. The In component value in the p-type L1 layer 161 may exceed the In component value in the quantum barrier layer, or may exceed the In component value in the quantum well layer. The main function of the p-type L1 layer 161 is to match the lattice of the quantum well layer and adjust the energy band of the last quantum barrier layer, effectively reducing the electron leakage in the quantum well layer.

The p-type L2 layer 162 is formed by p-AlGaN/AlInGaN superlattice, which refers to the use of AlGaN and AlInGaN stacked and grown in sequence, and p-type doping is performed. The thickness range of the p-type L2 layer 162 is: 5nm to 30nm. The Al component value in the p-type L2 layer 162 can exceed the Al component value in the quantum barrier layer, and can also exceed the Al component value in the quantum well layer. The In component value in the p-type L2 layer 162 can exceed the In component value in the quantum barrier layer, and can also exceed the In component value in the quantum well layer. The main function of the p-type L2 layer 162 is to improve the electron blocking effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, so that the carriers can be more effectively and uniformly injected into the light-emitting active area 150 of the device, perform radiation recombination, and improve the light efficiency of the ultraviolet light-emitting device 100.

The beneficial effects of the ultraviolet light emitting device 100 provided in this embodiment are as follows:

Introducing a p-type composite electron blocking layer 160 into the ultraviolet light-emitting device 100 and optimizing the energy band structure of the device can effectively increase the electron confinement effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, thereby increasing the radiation recombination rate of the ultraviolet light-emitting device 100 in the quantum well layer and improving the luminous efficiency of the device.

Second embodiment

This embodiment provides an ultraviolet light emitting device 100 using a composite electron blocking layer, which has a similar structure to that of the first embodiment, except that the material composition of the p-type composite electron blocking layer 160 in this embodiment is different.

The p-type composite electron blocking layer 160 includes a p-type L1 layer 161 and a p-type L2 layer 162 sequentially formed along the growth direction. The p-type L1 layer 161 is formed of p-AlInGaN, and the thickness of the p-type L1 layer 161 ranges from 5nm to 30nm. The Al component value in the p-type L1 layer 161 may exceed the Al component value in the quantum barrier layer, or may exceed the Al component value in the quantum well layer. The In component value in the p-type L1 layer 161 may exceed the In component value in the quantum barrier layer, or may exceed the In component value in the quantum well layer. The main function of the p-type L1 layer 161 is to match the lattice of the quantum well layer and adjust the energy band of the last quantum barrier layer, effectively reducing the electron leakage in the quantum well layer.

The p-type L2 layer 162 is formed of p-AlGaN, and the thickness of the p-type L2 layer 162 is in the range of 5nm to 30nm. The Al component value in the p-type L2 layer 162 can exceed the Al component value in the quantum barrier layer, and can also exceed the Al component value in the quantum well layer. The main function of the p-type L2 layer 162 is to improve the electron blocking effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, so that the carriers can be more effectively and uniformly injected into the light-emitting active area 150 of the device, perform radiation recombination, and improve the light efficiency of the ultraviolet light-emitting device 100.

Third embodiment

This embodiment provides an ultraviolet light emitting device 100 using a composite electron blocking layer, which has a similar structure to that of the first embodiment, except that the material composition of the p-type composite electron blocking layer 160 in this embodiment is different.

The p-type composite electron blocking layer 160 includes a p-type L1 layer 161 and a p-type L2 layer 162 sequentially formed along the growth direction. The p-type L1 layer 161 is formed of p-AlGaN, and the thickness of the p-type L1 layer 161 ranges from 5nm to 30nm. The Al component value in the p-type L1 layer 161 may exceed the Al component value in the quantum barrier layer, and may also exceed the Al component value in the quantum well layer. The main function of the p-type L1 layer 161 is to match the lattice of the quantum well layer and adjust the energy band of the last quantum barrier layer, effectively reducing the electron leakage in the quantum well layer.

The p-type L2 layer 162 is formed by p-AlGaN/AlInGaN superlattice, and the thickness of the p-type L2 layer 162 ranges from 5nm to 30nm. The Al component value in the p-type L2 layer 162 can exceed the Al component value in the quantum barrier layer, and can also exceed the Al component value in the quantum well layer. The In component value in the p-type L2 layer 162 can exceed the In component value in the quantum barrier layer, and can also exceed the In component value in the quantum well layer. The main function of the p-type L2 layer 162 is to improve the electron blocking effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, so that the carriers can be more effectively and uniformly injected into the light-emitting active area 150 of the device, perform radiation recombination, and improve the light efficiency of the ultraviolet light-emitting device 100.

Fourth embodiment

This embodiment provides an ultraviolet light emitting device 100 using a composite electron blocking layer, which has a similar structure to that of the first embodiment, except that the material composition of the p-type composite electron blocking layer 160 in this embodiment is different.

The p-type composite electron blocking layer 160 includes a p-type L1 layer 161 and a p-type L2 layer 162 sequentially formed along the growth direction. The p-type L1 layer 161 is formed of p-AlGaN, and the thickness of the p-type L1 layer 161 ranges from 5nm to 30nm. The Al component value in the p-type L1 layer 161 may exceed the Al component value in the quantum barrier layer, and may also exceed the Al component value in the quantum well layer. The main function of the p-type L1 layer 161 is to match the lattice of the quantum well layer and adjust the energy band of the last quantum barrier layer, effectively reducing the electron leakage in the quantum well layer.

The p-type L2 layer 162 is formed of p-AlInGaN, and the thickness of the p-type L2 layer 162 is in the range of 5nm to 30nm. The Al component value in the p-type L2 layer 162 may exceed the Al component value in the quantum barrier layer, and may also exceed the Al component value in the quantum well layer. The In component value in the p-type L2 layer 162 may exceed the In component value in the quantum barrier layer, and may also exceed the In component value in the quantum well layer. The main function of the p-type L2 layer 162 is to improve the electron blocking effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, so that the carriers can be more effectively and uniformly injected into the light-emitting active area 150 of the device, perform radiation recombination, and improve the light efficiency of the ultraviolet light-emitting device 100.

Fifth embodiment

Please refer to FIG. 2 . This embodiment provides a method for preparing an ultraviolet light-emitting device 100 using a composite electron blocking layer. The preparation method here is mainly used to prepare any one of the ultraviolet light-emitting devices 100 in the first to fourth embodiments.

The method for preparing the ultraviolet light emitting device 100 using the composite electron blocking layer comprises the following steps:

S1: Please refer to FIG. 3 . A low-temperature buffer layer 120 , a high-temperature layer 130 , an n-type Al _m Ga _1-m N layer 140 , and a light-emitting active region 150 are sequentially grown on the substrate 110 .

The light emitting active region 150 includes _{InxGa1 -xN} and _{AlyGa1 -yN} , 0.001≤x<y≤1. The light emitting active region 150 is formed by alternating growth of quantum well layers and quantum barrier layers. The thickness of the quantum well layers ranges from 1.5nm to 10nm, and the thickness of the quantum barrier layers ranges from 4nm to 20nm.

S2: Please refer to FIG. 4 , a p-type composite electron blocking layer 160 is grown on the light emitting active region 150 , wherein the p-type composite electron blocking layer 160 includes a p-type L1 layer 161 and a p-type L2 layer 162 sequentially formed along a growth direction.

To prepare the ultraviolet light emitting device 100 in the first embodiment, the p-type L1 layer 161 is formed of p-AlInGaN, and the thickness of the p-type L1 layer 161 is in the range of 5 nm to 30 nm. The p-type L2 layer 162 is formed of p-AlGaN/AlInGaN superlattice, and the thickness of the p-type L2 layer 162 is in the range of 5 nm to 30 nm.

To prepare the ultraviolet light emitting device 100 in the second embodiment, the p-type L1 layer 161 is formed of p-AlInGaN, and the thickness of the p-type L1 layer 161 is in the range of 5 nm to 30 nm. The p-type L2 layer 162 is formed of p-AlGaN, and the thickness of the p-type L2 layer 162 is in the range of 5 nm to 30 nm.

To prepare the ultraviolet light emitting device 100 in the third embodiment, the p-type L1 layer 161 is formed of p-AlGaN, and the thickness of the p-type L1 layer 161 is in the range of 5 nm to 30 nm. The p-type L2 layer 162 is formed of p-AlGaN/AlInGaN superlattice, and the thickness of the p-type L2 layer 162 is in the range of 5 nm to 30 nm.

To prepare the ultraviolet light emitting device 100 in the fourth embodiment, the p-type L1 layer 161 is formed of p-AlGaN, and the thickness of the p-type L1 layer 161 is in the range of 5 nm to 30 nm. The p-type L2 layer 162 is formed of p-AlInGaN, and the thickness of the p-type L2 layer 162 is in the range of 5 nm to 30 nm.

The main function of the p-type L1 layer 161 is to match the lattice of the quantum well layer and adjust the energy band of the last quantum barrier layer, effectively reducing the electron leakage in the quantum well layer. The main function of the p-type L2 layer 162 is to improve the electron blocking effect, enhance the hole injection efficiency, and the current expansion capability during carrier injection, so that the carriers can be more effectively and evenly injected into the light-emitting active area 150 of the device for radiation recombination, thereby improving the light efficiency of the ultraviolet light-emitting device 100.

In addition, the In composition value of AlInGaN in the p-type L1 layer 161 and the p-type L2 layer 162 may be higher than the In composition value in the quantum well layer, which has the function of adjusting the polarization intensity and direction.

S3 : Referring to FIG. 1 , a p-type Al _n Ga _1-n N layer 170 and a contact layer 180 are sequentially grown on the p-type composite electron blocking layer 160 .

This application only introduces in detail the example of applying the p-type composite electron blocking layer 160 to the ultraviolet light-emitting device 100. The p-type composite electron blocking layer 160 provided in this application can of course also be applied to semiconductor devices of other structural forms, which will not be repeated here. As long as the concept of the p-type composite electron blocking layer 160 provided in this application is used, it should fall within the scope of protection required by this application.

It should be noted that the values mentioned in this application, including the values of thickness, are only relatively reliable values obtained by the applicant through experiments and measurements, rather than strictly limiting the corresponding parameters to only these values. Those skilled in the art may conduct further experiments based on the scheme of this application to obtain other values with similar effects, and these values do not deviate from the core of this application and should also fall within the scope of protection claimed in this application.

The materials used in each layer structure in this application are only relatively reliable materials obtained by the applicant through experiments, and are not strictly limited to these materials. Those skilled in the art may conduct further experiments based on the scheme of this application to obtain other materials with similar effects. These materials do not deviate from the core of this application and should also fall within the scope of protection claimed in this application.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (8)

1. An ultraviolet light emitting device adopting a composite electron blocking layer is characterized in that the ultraviolet light emitting device comprises a substrate (110) and a low-temperature buffer layer (120), a high-temperature layer (130), an N-type Al _mGa_1-m N layer (140), a light emitting active region (150), a p-type composite electron blocking layer (160), a p-type Al _nGa_1-n N layer (170) and a contact layer (180) which are sequentially grown on the substrate (110); the p-type composite electron blocking layer (160) comprises a p-type L1 layer (161) and a p-type L2 layer (162) which are sequentially formed along the growth direction, wherein the Al component value In the p-type L1 layer (161) and the Al component value In the p-type L2 layer (162) are larger than the Al component value In the quantum barrier layer In the light-emitting active region (150), and the In component value In the p-type L1 layer (161) and the In component value In the p-type L2 layer (162) are larger than the In component value In the quantum well layer In the light-emitting active region (150).

2. The ultraviolet light emitting device according to claim 1, wherein the p-type L1 layer (161) is formed using p-AlInGaN and the p-type L2 layer (162) is formed using a p-AlGaN/AlInGaN superlattice.

3. The ultraviolet light emitting device according to claim 1, wherein the p-type L1 layer (161) is formed using p-AlInGaN and the p-type L2 layer (162) is formed using p-AlGaN.

4. The ultraviolet light emitting device according to claim 1, wherein the p-type L1 layer (161) is formed using p-AlGaN and the p-type L2 layer (162) is formed using a p-AlGaN/AlInGaN superlattice.

5. The ultraviolet light emitting device according to claim 1, wherein the p-type L1 layer (161) is formed using p-AlGaN, and the p-type L2 layer (162) is formed using p-AlInGaN.

6. The ultraviolet light emitting device according to claim 1, wherein the thickness of the p-type L1 layer (161) ranges from: 5 nm-30 nm, wherein the thickness range of the p-type L2 layer (162) is as follows: 5nm to 30nm.

7. The ultraviolet light emitting device according to claim 1, wherein Al composition values, in composition values of p-AlGaN or p-AlInGaN In the p-type L1 layer (161) and the p-type L2 layer (162) are constant In respective monolayers or linearly graded.

8. A method of fabricating an ultraviolet light emitting device employing a composite electron blocking layer, comprising: a low temperature buffer layer (120), a high temperature layer (130), an N-type Al _mGa_1-m N layer (140), a light emitting active region (150), a p-type composite electron blocking layer (160), a p-type Al _nGa_1-n N layer (170) and a contact layer (180) which are sequentially grown on a substrate (110); the p-type composite electron blocking layer (160) comprises a p-type L1 layer (161) and a p-type L2 layer (162) which are sequentially formed along the growth direction, wherein the Al component value In the p-type L1 layer (161) and the Al component value In the p-type L2 layer (162) are larger than the Al component value In the quantum barrier layer In the light-emitting active region (150), and the In component value In the p-type L1 layer (161) and the In component value In the p-type L2 layer (162) are larger than the In component value In the quantum well layer In the light-emitting active region (150).