CN108011004B - Light emitting diode with combined type back silver-plated reflecting layer - Google Patents

Abstract

The present invention relates to a kind of light emitting diodes with combined type back silver-plated reflecting layer.By being inserted into a silicon carbide layer between Sapphire Substrate and argentum reflecting layer, to solve the problems, such as that the two can not stick and form argentiferous mirror structure.Silicon carbide and silver-colored adhesion mutually are good, and compared to gallium nitride, it does not need to enhance by high annealing alloying and stick, silicon carbide also has very high transparency for visible light wave range simultaneously, so can be very good the argentiferous back plating mirror structure that construction has high reflectance as adhesion layer using silicon carbide layer.

Description

Light-emitting diode with composite back-plated reflective layer

technical field

The invention relates to a light-emitting diode, more specifically, to a light-emitting diode with a composite back-plated reflective layer.

Background technique

Since the beginning of the 21st century, the lighting industry has officially ushered in the third generation—the era of semiconductor lighting, and light-emitting diodes based on gallium nitride-based materials have become the mainstream of today's semiconductor lighting industry. Among them, the front-loaded gallium nitride-based light-emitting diode chip with sapphire as the growth substrate is the most common and widely used in the industry. For gallium nitride-based light-emitting diodes with a front-mount structure, in order to improve light extraction efficiency, a reflector is usually added to the back of the sapphire substrate. The structure of the back-plated reflector can be metal, or a transparent dielectric stack (such as a distributed Bragg reflector, DBR for short), or a combination of the two. Aluminum is generally used as the metal material for the back plating of sapphire, because although the reflectivity of silver is higher, the adhesion between silver and sapphire is extremely poor, so it cannot be directly used as the reflective layer of back plating. If silver is to be used as a mirror, a transparent adhesive layer must be introduced between the sapphire and silver. Chinese patent ZL201210074327.4 achieves a silver-containing back-plated reflector structure by introducing gallium nitride as an adhesion layer. As shown in Figure 1, it is a typical light-emitting diode structure diagram using the existing back-plating technology, which includes a sapphire substrate 100, a buffer layer 101, an n-type gallium nitride-based epitaxial layer 102, a light-emitting layer 103, and a p-type gallium nitride base epitaxial layer 104 , transparent conductive layer 110 , P electrode 111 , N electrode 112 , GaN-based adhesion layer 120 and silver reflective layer 130 . In the actual production process, high temperature annealing above 400°C is required to fuse the gallium nitride in the adhesion layer 120 and the silver in the reflective layer 130 to form an alloy to enhance the adhesion performance. The higher the annealing temperature is, the better the adhesion is. However, for If the formed metal electrode contacts are subjected to high temperature, the contact performance will be deteriorated easily, resulting in an increase in the operating voltage.

Therefore, it is necessary to improve the above-mentioned back-plating reflective layer solution to solve the limitations of the prior art.

Contents of the invention

The main purpose of the present invention is to provide a light-emitting diode with a composite back-plated reflective layer. By inserting a silicon carbide layer between the sapphire substrate and the silver reflective layer, the problem that the two cannot be adhered is solved and a silver-containing reflective layer is formed. mirror structure. Silicon carbide and silver have good adhesion to each other, and compared with gallium nitride, it does not need to be alloyed by high temperature annealing to enhance the adhesion. At the same time, silicon carbide has a very high transparency for the visible light band, so the use of silicon carbide layer as the adhesion layer can be constructed with High reflectivity silver back plated mirror structure.

According to the light-emitting diode with a composite back-plated reflective layer for achieving the above object, its structure includes:

Sapphire substrate;

GaN-based semiconductor stacks, formed on the first surface of the sapphire substrate, the GaN-based semiconductor stacks include a first conductive semiconductor layer, a second conductive semiconductor layer, and a layer between the two luminous layer;

A composite back-plate reflective layer is formed on the second surface of the transparent substrate opposite to the first surface, and from the second surface, the composite back-plate reflective layer sequentially includes a silicon carbide adhesion layer and a silver metal reflector Floor.

In the present invention, the silicon carbide adhesion layer can be formed by chemical epitaxial growth, such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), etc.; physical deposition can also be used. In terms of the thickness of silicon carbide, a stable mirror structure can be obtained by controlling it within 100 nanometers.

Of course, in order to further improve the reflectivity, a transparent medium layer stack such as a distributed Bragg reflector (DBR) can be added on the above basis. According to the light-emitting diode with a composite back-plated reflective layer for achieving the above object, its structure includes:

Sapphire substrate;

GaN-based semiconductor stacks, formed on the first surface of the sapphire substrate, the GaN-based semiconductor stacks include a first conductive semiconductor layer, a second conductive semiconductor layer, and a layer between the two luminous layer;

The composite back-plate reflective layer is formed on the second surface of the sapphire substrate opposite to the first surface, and from the second surface, the composite back-plate reflective layer sequentially includes a refractive index that alternates between high and low periodically. The multiple layers of light-transmitting dielectric layer stack, silicon carbide adhesion layer and metallic silver reflective layer.

In the above invention, the silicon carbide adhesion layer must be formed by physical deposition, such as evaporation or sputtering.

Description of drawings

Fig. 1 is a schematic structural view of a light-emitting diode chip with a back-plated reflective layer in the prior art;

Fig. 2 is a schematic structural view of a light-emitting diode chip with a composite back-plated reflective layer according to an embodiment of the present invention;

FIG. 3 is a schematic structural view of a light emitting diode chip with a composite back-plated reflective layer according to another embodiment of the present invention.

Explanation of component symbols in the figure:

100: sapphire substrate

101: buffer layer

102: n-type GaN-based epitaxial layer

103: Luminous layer

104: p-type GaN-based epitaxial layer

110: ITO transparent conductive layer

111: P electrode

112: N electrode

120: Gallium Nitride Adhesion Layer

130: silver reflective layer

200: Sapphire substrate

201: buffer layer

202: n-GaN layer

203: Multiple Quantum Well Layers

204: p-GaN layer

210: ITO transparent conductive layer

211: P electrode

212: N electrode

220: DBR

230: Silicon carbide adhesion layer

240: silver reflector

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

A light-emitting diode chip structure with a composite back-plated reflective layer as shown in Figure 2, including a sapphire substrate 200, a buffer layer 201, an n-GaN layer 202, a multi-quantum well active layer 203, and a p-GaN layer 204 , ITO transparent conductive layer 210 , P electrode 211 , N electrode 212 , silicon carbide adhesion layer 230 , and silver mirror 240 . Wherein, the sapphire substrate 200 has two main surfaces, a front surface and a back surface; the buffer layer 201 is formed on the front surface of the sapphire substrate 200; the n-GaN layer 202 is formed on the buffer layer 201; the multiple quantum wells have The source layer 203 is formed on the n-GaN layer 202; the p-GaN layer 204 is formed on the multi-quantum well active layer 203; the ITO layer 210 is formed on the p-GaN layer 204; the p-electrode 211 is formed on the ITO layer 210; the N electrode 212 is formed on the n-GaN layer 202; the silicon carbide adhesion layer 230 is formed on the back surface of the sapphire substrate 200, and its thickness is 500 angstroms; the silver mirror 240 is formed on the silicon carbide adhesion layer 230 superior.

In order to further improve the reflectivity of the back-plated structure, we can also introduce a distributed Bragg reflector (DBR) on the basis of the structure of the above-mentioned embodiment, as shown in Figure 3. LED chip structure, including sapphire substrate 200, buffer layer 201, n-GaN layer 202, multi-quantum well active layer 203, p-GaN layer 204, ITO transparent conductive layer 210, P electrode 211, N electrode 212, DBR220 , a silicon carbide adhesion layer 230 , and a silver mirror 240 . Wherein, the sapphire substrate 200 has two main surfaces, a front surface and a back surface; the buffer layer 201 is formed on the front surface of the sapphire substrate 200; the n-GaN layer 202 is formed on the buffer layer 201; the multiple quantum wells have The source layer 203 is formed on the n-GaN layer 202; the p-GaN layer 204 is formed on the multi-quantum well active layer 203; the ITO layer 210 is formed on the p-GaN layer 204; the p-electrode 211 is formed on the ITO layer 210; the N electrode 212 is formed on the n-GaN layer 202; the DBR is formed on the back surface of the sapphire substrate 200, and its structure is 6 pairs of silicon dioxide and titanium dioxide with a thickness of 1/4 dominant wavelength; the silicon carbide adhesion layer 230 is formed on DBR 220 with a thickness of 500 Angstroms; silver mirror 240 is formed on SiC adhesion layer 230 .

The light-emitting diode with the above structure has a "sapphire/silicon carbide/silver" back-plated reflective layer structure. Compared with the "sapphire/gallium nitride/silver" structure, this structure not only retains a very high reflectivity, but also avoids damage to the device. Compared with the annealing process that causes adverse effects, it is more feasible and superior in production.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection.

Claims (8)

1. Light-emitting diodes with a composite back-plated reflective layer, including: Sapphire substrate; GaN-based semiconductor stacks, formed on the first surface of the sapphire substrate, the GaN-based semiconductor stacks include a first conductive semiconductor layer, a second conductive semiconductor layer, and a layer between the two luminous layer; A composite back-plate reflective layer is formed on the second surface of the sapphire substrate opposite to the first surface, and from the second surface, the composite back-plate reflective layer sequentially includes a silicon carbide adhesion layer and a metallic silver reflector Floor. 2. The light-emitting diode with a composite back-plated reflective layer according to claim 1, wherein the silicon carbide adhesion layer is formed by chemical deposition and physical deposition. 3 . The light-emitting diode with composite back-plated reflective layer according to claim 1 , wherein the silicon carbide adhesion layer has a thickness ranging from 0.1 to 1000 nanometers. 4 . The light-emitting diode with composite back-plated reflective layer according to claim 1 , wherein the thickness of the silicon carbide adhesion layer ranges from 1 to 100 nanometers. 5. Light-emitting diodes with composite back-plated reflective layers, including: Sapphire substrate; GaN-based semiconductor stacks, formed on the first surface of the sapphire substrate, the GaN-based semiconductor stacks include a first conductive semiconductor layer, a second conductive semiconductor layer, and a layer between the two luminous layer; The composite back-plate reflective layer is formed on the second surface of the sapphire substrate opposite to the first surface, and from the second surface, the composite back-plate reflective layer sequentially includes a refractive index that alternates between high and low periodically. The multiple layers of light-transmitting dielectric layer stack, silicon carbide adhesion layer and metallic silver reflective layer. 6 . The light-emitting diode with composite back-plated reflective layer according to claim 5 , wherein the SiC adhesion layer is formed by physical deposition. 7 . The light-emitting diode with composite back-plated reflective layer according to claim 5 , wherein the silicon carbide adhesion layer has a thickness ranging from 0.1 to 1000 nanometers. 8 . The light-emitting diode with composite back-plated reflective layer according to claim 5 , wherein the silicon carbide adhesion layer has a thickness ranging from 1 to 100 nanometers.