CN102064260A - Device structure of grid modulation positively-mounted structure GaN base light emitting diode and manufacturing method - Google Patents

Abstract

A GaN-based light-emitting diode structure with gate modulation front-mount structure, comprising: a sapphire substrate; an n-type GaN layer, the n-type GaN layer is fabricated on the sapphire substrate, and a mesa is formed on one side of the n-type GaN layer , the depth of the mesa is less than the thickness of the n-type GaN layer; a multi-quantum well active layer, the multi-quantum well active layer is fabricated on the other side of the n-type GaN layer without the mesa; a p-type GaN layer, the The p-type GaN layer is made on the multi-quantum well active layer; a P electrode is made on the side of the p-type GaN layer away from the mesa; an N electrode is made on the mesa above the n-type GaN layer above; a gate insulating layer, which is fabricated on the other side of the p-type GaN layer without the P electrode; and a gate electrode, which is fabricated on the gate insulating layer.

Description

Device structure and fabrication method of GaN-based light-emitting diode with gate modulation positive structure

technical field

The invention is used in the technical field of manufacturing semiconductor optoelectronic devices, and specifically relates to a device structure and a preparation method of a novel gate modulation GaN-based light-emitting diode.

Background technique

GaN-based semiconductors are new types of wide-bandgap direct-bandgap semiconductor materials with excellent physical and chemical properties. High-power LEDs based on InGaN quantum well structures are currently a hot spot in the field of semiconductor optoelectronics research and a leader in the development of related industries. At present, group III nitrides have been widely used in many fields such as color display and decorative lighting.

Quantum well light-emitting structure is a typical example of the application of quantum physics in the field of optoelectronics. When the thickness of the quantum well is reduced to the nanometer level, the carrier density of states is distributed in steps, so that at the same injection level, it is easier to realize electron, space Hole recombination to obtain a light emission spectrum with stable wavelength and narrower spectral lines. However, group III nitrides with a brazerite structure have a hexagonal crystal structure, which is less symmetric than the cubic crystal phase structure and has a strong spontaneous polarization field; in addition, compared with the traditional GaAs system quantum well structure, the InGaN/GaN system There is a larger lattice mismatch, which leads to a stronger piezoelectric polarization electric field under the action of lattice stress, which can usually reach MV/cm, causing a significant quantum-confined Stark effect. Under the action of the polarized electric field, the wave functions of conduction band electrons and valence band holes in the quantum well are separated in space, and the recombination probability of electrons and holes is reduced, thereby reducing the radiation recombination efficiency. In addition, affected by the polarization effect, as the injection current increases, the LED emission wavelength shifts, usually reaching 3-5nm. The drift of luminous wavelength will cause the following problems in practical applications: In terms of display, the change of wavelength will make it extremely difficult to control full-color display, and at the same time, too wide a spectrum will lead to color impurity; in the field of white light lighting, the change of blue light wavelength will cause The color or color temperature of white light changes.

Prior to the present invention, the polarization effect was usually reduced by means of optimizing epitaxial growth, lattice-matched quantum well structure or non-polar surface growth, but the effect was not satisfactory.

Contents of the invention

The purpose of the present invention is to provide a novel method for preparing the device structure of GaN-based light-emitting diodes with gate modulation frontal structure. The structure uses an external electric field to balance the polarization electric field generated by the spontaneous polarization and piezoelectric polarization of the InGaN/GaN system through the gate insulating medium and the gate electrode. The influence of the polarization effect on the device characteristics is reduced, and the modulation of the luminescence characteristics of the GaN-based LED by the gate electrode is realized. The invention provides an effective way for reducing the polarization effect of the group III nitride light-emitting device and preparing GaN-based LEDs with high efficiency and good wavelength consistency.

Technical scheme of the present invention is as follows:

The present invention provides a GaN-based light-emitting diode structure with gate modulation positive structure, including:

a sapphire substrate;

An n-type GaN layer, the n-type GaN layer is fabricated on a sapphire substrate, a mesa is formed on one side of the n-type GaN layer, and the depth of the mesa is less than the thickness of the n-type GaN layer;

A multi-quantum well active layer, the multi-quantum well active layer is fabricated on the other side of the n-type GaN layer without mesas;

A p-type GaN layer, the p-type GaN layer is fabricated on the multi-quantum well active layer;

A p-electrode, the p-electrode is fabricated on the side of the p-type GaN layer away from the mesa;

An N electrode, the N electrode is fabricated on the mesa above the n-type GaN layer;

A gate insulating layer, which is fabricated on the other side of the p-type GaN layer without the P electrode;

A gate electrode is fabricated on the gate insulating layer.

The material of the gate insulating layer is SiO ₂ , SiN or SiON, and the thickness is 0.001-0.1um.

Wherein the gate electrode is a metal electrode or a transparent conductive electrode, and the gate electrode can realize the modulation of the characteristics of the GaN-based light-emitting diode.

The invention provides a method for preparing a GaN-based light-emitting diode structure with a gate modulation positive structure, which includes the following steps:

Step 1: sequentially grow an n-type GaN layer, a multi-quantum well active layer and a p-type GaN layer on a sapphire substrate;

Step 2: Etching downward from the p-type GaN layer by dry etching to form a mesa on one side, and the etching depth reaches within the n-type GaN layer;

Step 3: preparing a P electrode on the side away from the mesa above the p-type GaN layer;

Step 4: Prepare N electrodes on the table;

Step 5: preparing a gate insulating layer on the other side of the p-type GaN layer without the P electrode;

Step 6: Prepare a gate electrode on the gate insulating layer to complete the fabrication of the front-mount device.

The gate insulating layer is prepared by deposition or sputtering, and the material of the gate insulating layer is SiO ₂ , SiN or SiON.

Wherein the thickness of the gate insulating layer is 0.001-0.1um.

The gate electrode is prepared by photolithography and adhesive stripping process, and the gate electrode is a metal electrode or a transparent conductive electrode. The gate electrode 8 can realize the modulation of the characteristics of the GaN-based light-emitting diode.

Wherein the thickness of the p-type GaN layer is 0.01-0.5um.

Description of drawings

In order to further illustrate the contents of the present invention, the present invention is described in detail below in conjunction with specific embodiments, wherein:

Figure 1 is a schematic cross-sectional view of a GaN-based power LED epitaxial material. On a sapphire substrate 1, an n-GaN layer 2, an active layer 3, and a p-GaN layer 4 are grown by epitaxy;

FIG. 2 is a schematic diagram of the structure of a front-loaded GaN-based LED prepared by using the epitaxial material shown in FIG. 1 . A p-electrode 5 is prepared on the surface of the p-GaN layer 4 , and an n-electrode 6 is prepared on the surface of the mesa 21 .

FIG. 3 is a schematic diagram of preparing a gate insulating layer 7 by depositing or sputtering on the p-GaN layer 4 of the front-mount LED chip shown in FIG. 2 .

FIG. 4 is a schematic diagram of preparing a gate electrode 8 on the gate insulating layer 7 of the front-mount GaN-based LED shown in FIG. 2 .

Detailed ways

Please refer to FIG. 4, the present invention provides a gate modulation GaN-based light-emitting diode structure, including:

A sapphire substrate 1;

An n-type GaN layer 2, the n-type GaN layer 2 is fabricated on the sapphire substrate 1, a mesa 21 is formed on one side of the n-type GaN layer 2, and the depth of the mesa 21 is smaller than the thickness of the n-type GaN layer 2;

A multi-quantum well active layer 3, the multi-quantum well active layer 3 is fabricated on the other side of the n-type GaN layer 2 without the mesa 21, the layer structure will limit the injection of carriers, and the injection of carriers The flow particles will recombine and emit light in this layer;

A p-type GaN layer 4, the p-type GaN layer 4 is fabricated on the multi-quantum well active layer 3, and the thickness of the p-type GaN layer 4 is 0.01-0.5um;

A p-electrode 5, the p-electrode 5 is fabricated on the side of the p-type GaN layer 4 away from the mesa 21;

An N electrode 6, the N electrode 6 is fabricated on the mesa 21 above the n-type GaN layer 2;

A gate insulating layer 7, the gate insulating layer 7 is made on the other side of the p-type GaN layer 4 without the P electrode 5, the material of the gate insulating layer 7 is SiO ₂ , SiN or SiON, the gate insulating The thickness of layer 7 is 0.001-0.1um. Through this layer structure, an external electric field is used to balance the polarization electric field generated by the spontaneous polarization and piezoelectric polarization of the InGaN/GaN system. Reduce the influence of the polarization effect on the device characteristics, realize the modulation of the gate electrode to the GaN-based LED luminous characteristics, including the modulation of the luminous wavelength, the modulation of the luminous intensity, etc.;

A gate electrode 8 is fabricated on the gate insulating layer 7, and the gate electrode 8 is a metal electrode or a transparent conductive electrode.

Please refer to FIG. 1 to FIG. 4, the present invention provides a method for preparing a GaN-based light-emitting diode structure for gate modulation, which includes the following steps:

Step 1: growing an n-type GaN layer 2, a multi-quantum well active layer 3 and a p-type GaN layer 4 sequentially on a sapphire substrate 1, and the thickness of the p-type GaN layer 4 is 0.01-0.5um;

Step 2: using a dry etching method to etch downward from the p-type GaN layer 4 to form a mesa 21 on one side, and the etching depth reaches within the n-type GaN layer 2;

Step 3: Prepare a P electrode 5 on the side of the p-type GaN layer 4 away from the mesa 21, and its electrode metal system is a transparent conductive electrode plus NiAgNiAu, NiAgPtAu, NiAgNiAu, etc.;

Step 4: preparing the N electrode 6 on the table 21;

Step 5: Prepare a gate insulating layer 7 on the other side of the p-type GaN layer 4 without the P electrode 5, the gate insulating layer 7 is prepared by deposition or sputtering, and the material of the gate insulating layer 7 is SiO ₂ , SiN or SiON, the thickness of the gate insulating layer 7 is 0.001-0.1um;

Step 6: Prepare the gate electrode 8 on the gate insulating layer 7. The gate electrode 8 is prepared by photolithography and adhesive stripping process. The gate electrode 8 is a metal electrode or a transparent conductive electrode. By applying a voltage signal to the gate electrode 8 , to realize the modulation of the characteristics of GaN-based light-emitting diodes, and to complete the fabrication of gate-modulated front-mounted devices.

The above is only a specific implementation mode in the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technology can easily think of changes or replacements within the technical scope disclosed in the present invention. All should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (8)

1. A GaN-based light-emitting diode structure with gate modulation positive structure, comprising: a sapphire substrate; An n-type GaN layer, the n-type GaN layer is fabricated on a sapphire substrate, a mesa is formed on one side of the n-type GaN layer, and the depth of the mesa is less than the thickness of the n-type GaN layer; A multi-quantum well active layer, the multi-quantum well active layer is fabricated on the other side of the n-type GaN layer without mesas; A p-type GaN layer, the p-type GaN layer is fabricated on the multi-quantum well active layer; A p-electrode, the p-electrode is fabricated on the side of the p-type GaN layer away from the mesa; An N electrode, the N electrode is fabricated on the mesa above the n-type GaN layer; A gate insulating layer, which is fabricated on the other side of the p-type GaN layer without the P electrode; A gate electrode is fabricated on the gate insulating layer. 2. The GaN-based light-emitting diode structure with gate modulation front-mount structure according to claim 1, wherein the material of the gate insulating layer is SiO ₂ , SiN or SiON, and the thickness is 0.001-0.1 um. 3. The GaN-based light-emitting diode structure with gate modulation front-mount structure according to claim 1, wherein the gate electrode is a metal electrode or a transparent conductive electrode, and the gate electrode can realize the modulation of the characteristics of the GaN-based light-emitting diode. 4. A method for preparing a GaN-based light-emitting diode structure with gate modulation positive structure, comprising the steps of: Step 1: sequentially grow an n-type GaN layer, a multi-quantum well active layer and a p-type GaN layer on a sapphire substrate; Step 2: Etching downward from the p-type GaN layer by dry etching to form a mesa on one side, and the etching depth reaches within the n-type GaN layer; Step 3: preparing a P electrode on the side away from the mesa above the p-type GaN layer; Step 4: Prepare N electrodes on the table; Step 5: preparing a gate insulating layer on the other side of the p-type GaN layer without the P electrode; Step 6: Prepare a gate electrode on the gate insulating layer to complete the fabrication of the front-mount device. 5 . The method for fabricating a positive-mount GaN-based light-emitting diode structure with gate modulation according to claim 4 , wherein the gate insulating layer is prepared by deposition or sputtering, and the material of the gate insulating layer is SiO ₂ , SiN or SiON. 6 . The method for fabricating a positive-mount GaN-based light-emitting diode structure with gate modulation according to claim 4 , wherein the thickness of the gate insulating layer is 0.001-0.1 μm. 7. The fabrication method of the grid-modulated positive-mounted GaN-based light-emitting diode structure according to claim 4, wherein the gate electrode is prepared by photolithography and tape stripping process, the gate electrode is a metal electrode or a transparent conductive electrode, and the gate electrode 8 can realize the modulation of GaN-based light-emitting diode characteristics. 8 . The method for fabricating a positive-mount GaN-based light-emitting diode structure with gate modulation according to claim 4 , wherein the thickness of the p-type GaN layer is 0.01-0.5 um.

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