CN104779331A - GaN-based LED (Light-Emitting Diode) device with two-dimensional electron gas structure, and preparation method for GaN-based LED device - Google Patents

Abstract

The invention discloses a GaN-based LED (Light-Emitting Diode) device with a two-dimensional electron gas structure, and a preparation method for the GaN-based LED device. The LED device comprises a substrate, a GaN nucleating layer, a GaN buffer layer, a non-doped GaN layer, an N-type GaN layer, the two-dimensional electron gas structure, a multi-quantum well luminous layer and a P-type GaN layer. According to the LED device, the two-dimensional electron gas structure is an electron emission layer formed by alternately stacking a plurality of pairs of lightly-doped n-GaN layers/AlN layers/heavily-doped n+GaN layers from bottom to top, the overflow of electrons into a non-quantum well area for nonradiative recombination with electron holes under a heavy-current injection condition can be effectively inhibited, and in addition, by two-dimensional electron gas, the transverse spreading efficiency of the electrons can be improved to improve the luminous efficiency of LEDs under the heavy-current injection condition.

Description

A GaN-based LED device with a two-dimensional electron gas structure and its preparation method

technical field

The invention relates to the technical field of semiconductor light emitting devices, in particular to a GaN-based LED device with a two-dimensional electron gas structure and a preparation method thereof.

Background technique

A light-emitting diode (Light-Emitting Diode, LED) is a semiconductor electronic component that can emit light. This electronic component appeared as early as 1962. In the early days, it could only emit red light with low luminosity. Later, other monochromatic light versions were developed. Today, the light that can be emitted has covered visible light, infrared rays and ultraviolet rays, and the luminosity has also increased to a considerable extent. of luminosity. And the use is also used as indicator lights, display panels, etc. from the beginning; with the continuous advancement of technology, light-emitting diodes have been widely used in displays, TV lighting decoration and lighting.

LED is a solid-state semiconductor device that directly converts electrical energy into light energy. Compared with traditional light sources, LED has the characteristics of small size, long service life, fast response speed, and high luminous efficiency. Therefore, LED has become a new type of high-profile Green light sources have entered the field of lighting. With the increasing application scope of LED in the lighting and backlight market year by year, the application demand for medium and high power devices has increased significantly. However, LEDs have the problem of attenuation of luminous efficiency under high current injection, which limits the application of high power and high brightness LEDs to a certain extent. Development also restricts the development of LED in the field of general lighting.

Therefore, in view of the above technical problems, it is necessary to provide a GaN-based LED device with a two-dimensional electron gas structure and a preparation method thereof.

Contents of the invention

In view of this, the object of the present invention is to provide a GaN-based LED device with a two-dimensional electron gas structure and a preparation method thereof.

In order to achieve the above object, the technical solutions provided by the embodiments of the present invention are as follows:

A GaN-based LED device with a two-dimensional electron gas structure, the LED device sequentially includes:

Substrate;

a GaN nucleation layer on the substrate;

a GaN buffer layer on the GaN nucleation layer;

an undoped GaN layer on the GaN buffer layer;

An N-type GaN layer on the non-doped GaN layer;

A two-dimensional electron gas structure located on an N-type GaN layer, the two-dimensional electron gas structure is an electron emission composed of several pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers stacked alternately from bottom to top layer;

A multiple quantum well light-emitting layer on a two-dimensional electron gas structure;

A P-type GaN layer on the multiple quantum well light emitting layer.

As a further improvement of the present invention, the two-dimensional electron gas structure includes 3 to 10 pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers alternately stacked from bottom to top.

As a further improvement of the present invention, the thickness of the lightly doped n-GaN layer in the two-dimensional electron gas structure is 2-8 nanometers, and the thickness of the heavily doped n+GaN layer is 4-20 nanometers.

As a further improvement of the present invention, the thickness of the AlN layer in the two-dimensional electron gas structure is 0.6-2 nanometers.

As a further improvement of the present invention, both the lightly doped n-GaN layer and the heavily doped n+GaN layer are Si-doped, and the doping concentration of the lightly doped n-GaN layer is 2E17cm ^-3 ~ 2E18cm ^-3 , The doping concentration of the heavily doped n+GaN layer is 2E18cm ^-3 -6E18cm ^-3 .

As a further improvement of the present invention, the P-type GaN layer further includes a P-type GaN contact layer.

Correspondingly, a preparation method of a GaN-based LED device with a two-dimensional electron gas structure, the preparation method comprising:

providing a substrate;

growing a GaN nucleation layer on the substrate;

growing a GaN buffer layer on the GaN nucleation layer;

growing a non-doped GaN layer on the GaN buffer layer;

growing an N-type GaN layer on the non-doped GaN layer;

A two-dimensional electron gas structure is grown on the N-type GaN layer, and the two-dimensional electron gas structure is an electron emission composed of several pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers stacked alternately from bottom to top layer;

Growth of multi-quantum well light-emitting layer on two-dimensional electron gas structure;

A P-type GaN layer is grown on the multi-quantum well light-emitting layer.

As a further improvement of the present invention, the two-dimensional electron gas structure includes 3 to 10 pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers alternately stacked from bottom to top.

The present invention has the following beneficial effects:

The electron emission layer composed of several pairs of lightly doped n-GaN layer/AlN layer/heavily doped n+GaN layer alternately stacked in LED devices can effectively suppress the overflow of electrons to non-quantum well regions and holes under high current injection. Non-radiative recombination occurs, and at the same time, the lateral expansion efficiency of electrons is improved by means of two-dimensional electron gas, so as to improve the luminous efficiency of LEDs under high current injection.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 is a schematic structural diagram of a GaN-based LED device in the prior art;

FIG. 2 is a schematic structural view of a GaN-based LED device with a two-dimensional electron gas structure in a specific embodiment of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions in the present invention, 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 The embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

Referring to Fig. 1, it is a schematic structural diagram of a GaN-based LED device in the prior art, which includes, from bottom to top: sapphire substrate, GaN nucleation layer, GaN buffer layer, undoped GaN layer, N-type GaN layer, multi-quantum Well light-emitting layer, P-type GaN layer and P-type GaN contact layer.

In the prior art, GaN-based LED devices have the problem of attenuation of luminous efficiency under high current injection.

Referring to FIG. 2, in a specific embodiment of the present invention, the GaN-based LED device includes from bottom to top:

Substrate 10, in this embodiment, the substrate is a sapphire substrate, and in other embodiments, it can also be other substrate materials, such as Si, SiC, etc.;

The GaN nucleation layer 20 located on the substrate 10, preferably, the GaN nucleation layer is a low-temperature GaN nucleation layer grown under low temperature conditions;

a GaN buffer layer 30 on the GaN nucleation layer 20;

an undoped GaN layer 40 on the GaN buffer layer 30;

An N-type GaN layer 50 located on the non-doped GaN layer 40;

A two-dimensional electron gas structure 60 located on the N-type GaN layer 50;

A multi-quantum well light-emitting layer 70 located on the two-dimensional electron gas structure 60;

P-type GaN layer 80 located on the multi-quantum well light-emitting layer 70;

P-type GaN contact layer 90 located on P-type GaN layer 80 .

Wherein, the two-dimensional electron gas structure 60 is an electron emission layer composed of several pairs of lightly doped n-GaN layers 61 /AlN layers 62 /heavily doped n+GaN layers 63 alternately stacked. The two-dimensional electron gas structure can effectively inhibit the non-radiative recombination of electrons from overflowing to the non-quantum well region and holes under high current injection, and at the same time use the two-dimensional electron gas to improve the lateral expansion efficiency of electrons, so as to improve the performance of LED devices under high current. Luminous efficiency under injection.

The two-dimensional electron gas structure in the present invention includes 3 to 10 pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers alternately stacked from bottom to top.

In this embodiment, both the lightly doped n-GaN layer and the heavily doped n+ GaN layer are Si-doped, the doping concentration of the lightly doped n-GaN layer is 2E17cm ^-3 ~ 2E18cm ^-3 , and the heavily doped n+ The doping concentration of the GaN layer is 2E18cm ^-3 -6E18cm ^-3 .

Further, in this embodiment, the thickness of the lightly doped n-GaN layer is 2-8 nanometers, the thickness of the heavily doped n+GaN layer is 4-20 nanometers; the thickness of the AlN layer is 0.6-2 nanometers.

In the present invention, the doping concentration of Si in the electron emission layer composed of lightly doped n-GaN layer/AlN layer/heavily doped n+GaN layer alternately stacked structure, the thickness of lightly and highly doped n-GaN layer and the thickness of AlN layer All can be optimized and adjusted. AlN has a stronger polarization effect than AlGaN materials with a low aluminum composition, and a smaller thickness of the AlN layer (barrier layer) can induce a higher concentration of two-dimensional electron gas at the AlN/GaN interface. By adjusting the optimized combination, AlN and high-low concentration nGaN form the optimal two-dimensional electron gas structure composition, suppressing the overflow of electrons to the non-quantum well region and the non-radiative recombination of holes under high current injection, and improving the lateral expansion efficiency of electrons , thereby improving the luminous efficiency of the LED under high current injection.

Preferably, the lightly doped n-GaN layer/AlN layer/heavily doped n+GaN layer two-dimensional electron gas structure electron emission layer is 3-10 pairs, and when the number of this structure is less than 3 pairs, multiple quantum wells under high current The confinement effect on electrons will be weakened. When the logarithm is greater than 10 pairs, the crystal quality will decrease due to the large lattice mismatch between GaN and AlN. Both of these points will lead to a decrease in the optoelectronic performance of the LED.

In this embodiment, the substrate is a sapphire substrate, and the epitaxial layer is a GaN epitaxial layer. In other embodiments, the substrate can also be a Si substrate, SiC substrate, etc., and the epitaxial layer can also be GaAs, InP, InGaAsP, etc. .

Correspondingly, the present invention also discloses a method for preparing a GaN-based LED device with a two-dimensional electron gas structure, including:

providing a substrate;

growing a GaN nucleation layer on the substrate;

growing a GaN buffer layer on the GaN nucleation layer;

growing a non-doped GaN layer on the GaN buffer layer;

growing an N-type GaN layer on the non-doped GaN layer;

A two-dimensional electron gas structure is grown on the N-type GaN layer, and the two-dimensional electron gas structure is an electron emission composed of several pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers stacked alternately from bottom to top layer;

Growth of multi-quantum well light-emitting layer on two-dimensional electron gas structure;

Growing a P-type GaN layer on the multi-quantum well light-emitting layer;

A P-type GaN contact layer is grown on the P-type GaN layer.

Preferably, the two-dimensional electron gas structure includes 3 to 10 pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers alternately stacked from bottom to top.

Further, the GaN buffer layer is a low-temperature GaN buffer layer, and its growth temperature is 530°C to 550°C.

In summary, compared with the prior art, the present invention has the following beneficial effects:

The electron emission layer composed of several pairs of lightly doped n-GaN layer/AlN layer/heavily doped n+GaN layer alternately stacked in LED devices can effectively suppress the overflow of electrons to non-quantum well regions and holes under high current injection. Non-radiative recombination occurs, and at the same time, the lateral expansion efficiency of electrons is improved by means of two-dimensional electron gas, so as to improve the luminous efficiency of LEDs under high current injection.

It will be apparent to those skilled in the art that the invention is not limited to the details of the above-described exemplary embodiments, but that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Accordingly, the embodiments should be regarded in all points of view as exemplary and not restrictive, the scope of the invention being defined by the appended claims rather than the foregoing description, and it is therefore intended that the scope of the invention be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in the present invention. Any reference sign in a claim should not be construed as limiting the claim concerned.

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art.

Claims (8)

1. A GaN-based LED device with a two-dimensional electron gas structure, characterized in that, the LED device comprises sequentially from bottom to top: Substrate; a GaN nucleation layer on the substrate; a GaN buffer layer on the GaN nucleation layer; an undoped GaN layer on the GaN buffer layer; An N-type GaN layer on the non-doped GaN layer; A two-dimensional electron gas structure located on an N-type GaN layer, the two-dimensional electron gas structure is an electron emission composed of several pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers stacked alternately from bottom to top layer; A multiple quantum well light-emitting layer on a two-dimensional electron gas structure; A P-type GaN layer on the multiple quantum well light emitting layer. 2. The GaN-based LED device according to claim 1, wherein the two-dimensional electron gas structure comprises 3 to 10 pairs of lightly doped n-GaN layer/AlN layer/heavily doped n+GaN layer. 3. The GaN-based LED device according to claim 1, wherein the thickness of the lightly doped n-GaN layer in the two-dimensional electron gas structure is 2 to 8 nanometers, and the thickness of the heavily doped n+GaN layer is 4 to 20 nanometers. 4. The GaN-based LED device according to claim 1, wherein the thickness of the AlN layer in the two-dimensional electron gas structure is 0.6-2 nanometers. 5. The GaN-based LED device according to claim 1, characterized in that, both the lightly doped n-GaN layer and the heavily doped n+GaN layer are Si-doped, and the doping of the lightly doped n-GaN layer The impurity concentration is 2E17cm ^-3 -2E18cm ^-3 , and the doping concentration of the heavily doped n+GaN layer is 2E18cm ^-3 -6E18cm ^-3 . 6. The GaN-based LED device according to claim 1, characterized in that, the P-type GaN layer further includes a P-type GaN contact layer. 7. A preparation method of a GaN-based LED device with a two-dimensional electron gas structure as claimed in claim 1, wherein the preparation method comprises: providing a substrate; growing a GaN nucleation layer on the substrate; growing a GaN buffer layer on the GaN nucleation layer; growing a non-doped GaN layer on the GaN buffer layer; growing an N-type GaN layer on the non-doped GaN layer; A two-dimensional electron gas structure is grown on the N-type GaN layer, and the two-dimensional electron gas structure is an electron emission composed of several pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+GaN layers stacked alternately from bottom to top layer; Growth of multi-quantum well light-emitting layer on two-dimensional electron gas structure; A P-type GaN layer is grown on the multi-quantum well light-emitting layer. 8. The preparation method according to claim 7, wherein the two-dimensional electron gas structure comprises 3 to 10 pairs of lightly doped n-GaN layers/AlN layers/heavily doped n+ GaN layer.