LED epitaxial structure capable of regulating and controlling wavelength

Abstract

The utility model belongs to the technical field of LED epitaxial structures, and particularly discloses a wavelength-adjustable LED epitaxial structure, which comprises a patterned substrate, a buffer layer grown on the patterned substrate, a 3D + GR layer grown on the buffer layer, an N layer grown on the GR layer, and a polarization improvement layer grown between the GR layer and the N layer or between the buffer layer and the 3D layer. And the polarization improvement layer sequentially comprises an AlN1 layer, a ferroelectric material layer and an AlN2 layer. According to the utility model, a ferroelectric material layer (BaTiO, PbZrTiO3 and the like) is inserted into an N-type semiconductor, and spontaneous polarization can be generated under the action of an external electric field or stress by utilizing an important characteristic, namely polarization reversibility, of a ferroelectric material. When the ferroelectric material is plated below the N layer (electronic conducting layer), the polarization direction of the ferroelectric material can be regulated and controlled through an external electric field or stress. By adjusting the polarization direction and intensity, the fine adjustment of PN junction energy level distribution can be realized, so that the wavelength can be indirectly and quickly adjusted.

Description

Technical Field

[0001] This utility model belongs to the field of LED epitaxial structure technology, specifically relating to an LED epitaxial structure with adjustable wavelength. Background Technology

[0002] As LED technology matures, it is increasingly being applied to various aspects of life, especially in emerging industries. Its rapid dynamic response makes images more vivid, colors richer, and enhances visual effects. In communications, it may be used in visible light communication (VLC), transmitting data quickly and securely through rapid color changes. Other applications may include medicine and agriculture, such as using different wavelengths of light to promote plant growth or for sterilization.

[0003] The wavelength of an LED directly affects its emitted color and luminous efficacy. By adjusting the wavelength, the luminous efficacy and color performance of an LED can be optimized, allowing it to achieve the best results in different applications. However, existing wavelength adjustment technologies have the following drawbacks:

[0004] 1. By designing multilayer quantum wells (such as InGaN / GaN quantum wells), the binding energy of electrons and holes can be changed by utilizing the quantum confinement effect, thereby achieving the control of the emission wavelength. The disadvantage is that the wavelength cannot be controlled in real time and the emission efficiency is affected.

[0005] 2. The bandgap of semiconductor materials can be altered by applying mechanical stress or introducing lattice strain. For example, in GaN materials, compressive or tensile strain can adjust the emission wavelength. The disadvantages are that stress introduction may lead to material fatigue and performance degradation, and the tuning range is limited, generally suitable for narrow wavelength tuning.

[0006] 3. Light output can be modulated by designing gratings or periodic nanostructures on or inside the epitaxial surface of the LED. This structure can change the direction and wavelength characteristics of light. Disadvantages include: complex fabrication process, requiring high-precision nanofabrication technology, and structural design may limit the flexibility of the device. Utility Model Content

[0007] This invention addresses the problems in the background art by providing an LED epitaxial structure with adjustable wavelength. By changing the epitaxial structure, the LED epitaxial wavelength can be adjusted in real time.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An tunable wavelength LED epitaxial structure includes a patterned substrate, a buffer layer grown on the patterned substrate, a 3D+GR layer grown on the buffer layer, an N layer grown on the GR layer, and a polarization improvement layer grown between the GR layer and the N layer or between the buffer layer and the 3D layer. The polarization improvement layer sequentially includes an AlN1 layer, a ferroelectric material layer, and an AlN2 layer.

[0010] Preferably, the ferroelectric material layer is BaTiO3 or PbZrTiO3.

[0011] Preferably, the AlN layer can also be replaced with an AlGaN layer.

[0012] Preferably, the AlN / AlGaN growth conditions are: a growth thickness of 25~100 nm and a pressure of 100~200 torr.

[0013] Preferably, the growth conditions for the ferroelectric material are: pressure of 50~100 Torr and growth thickness of 1~500 nm.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] This invention utilizes a key characteristic of ferroelectric materials—reversible polarization—by inserting a ferroelectric material layer (such as BaTiO3 or PbZrTiO3) into an N-type semiconductor. This allows for spontaneous polarization under an applied electric field or stress. When the ferroelectric material is deposited below the N-layer (electronically conductive layer), its polarization direction can be controlled by an applied electric field or stress. By adjusting the polarization direction and intensity, precise adjustment of the PN junction energy level distribution can be achieved, thereby indirectly and rapidly adjusting the wavelength. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model.

[0017] Figure 2 This is a comparison diagram of the electronic band structure of this utility model. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by this utility model in order to achieve the intended utility model purpose, the following detailed description of the specific implementation methods, structure, features and effects of this utility model is provided in conjunction with the accompanying drawings and preferred embodiments.

[0019] like Figure 1As shown, the present invention provides an tunable wavelength LED epitaxial structure, taking PZT (PbZrTiO3) material as an example: a buffer layer is grown on a patterned substrate, a UGaN layer is grown on it, an AlN1 layer is grown on it, a PZT layer is grown on it, an AlN2 layer is grown on it, an NGaN layer and an LED structure layer are grown on it.

[0020] The purpose of inserting an AlN layer onto UGaN is to reduce the lattice mismatch between GaN and the PZT ferroelectric layer, thereby reducing defects caused by an excessively high lattice constant. AlN growth conditions: thickness 25~100 nm, pressure 100~200 torr. PZT ferroelectric material growth conditions: pressure 50~100 Torr, thickness 1~500 nm.

[0021] Ferroelectric materials exhibit polarization properties, forming an electric dipole moment internally even without an external electric field. This spontaneous polarization is typically caused by asymmetries in the crystal structure. When an electric current is applied, a reverse internal electric field is formed within the ferroelectric material, thus improving the polarization effect. When ferroelectric materials are deposited under an N-layer (electronically conductive layer), their polarization direction can be modulated by an applied electric field or stress. By adjusting the polarization direction and intensity, the energy level distribution of the PN junction can be finely adjusted, thereby indirectly controlling the wavelength.

[0022] The polarization of ferroelectric materials creates an additional potential barrier or well on the surface of GaN semiconductors, thereby altering the energy level distribution of the PN junction.

[0023] If the polarization direction of the ferroelectric material creates a negative bias at the GaN layer surface (relative to the P layer), the barrier height at the PN junction will increase. This leads to electron-hole recombination in a higher energy region, effectively increasing the band gap Eg.

[0024] The polarization of ferroelectric materials can cause minute strains on the surface of GaN layers. This strain can cause distortion of the semiconductor lattice, thereby altering its bandgap.

[0025] by Figure 2 Taking the electronic band structure as an example, the growth conditions for ferroelectric materials are: pressure: 50~100 Torr, growth thickness: 1~500 nm. For AlN / AlGaN, the growth thickness is 25~100 nm, and the pressure is 100~200 Torr. A possible band structure is speculated as follows: As the current increases, the polarization effect of PZT ferroelectric materials leads to an increase in the MQW barrier height, a reduction in the well tilt, and an increase in the band gap, thus shortening the wavelength. This results in a faster dynamic color change response, making the image more vivid and the colors richer.

Claims

1. A wavelength-tunable LED epitaxial structure, comprising a patterned substrate, a buffer layer grown on the patterned substrate, a 3D+GR layer grown thereon, and an N layer grown on the GR layer, characterized in that: A polarization improvement layer is grown between the GR layer and the N layer or between the buffer layer and the 3D layer, wherein the polarization improvement layer comprises, in sequence, an AlN1 layer, a ferroelectric material layer and an AlN2 layer.

2. The tunable wavelength LED epitaxial structure as described in claim 1, characterized in that: The ferroelectric material layer is made of BaTiO3 or PbZrTiO3.

3. The tunable wavelength LED epitaxial structure as described in claim 1, characterized in that: The AlN layer is replaced with an AlGaN layer.

4. The tunable wavelength LED epitaxial structure as described in claim 3, characterized in that: The AlN / AlGaN growth thickness is 25~100nm.

5. A wavelength-tunable LED epitaxial structure as described in claim 1 or 2, characterized in that: The thickness of the ferroelectric material is 1~500nm.

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