CN112786757B

CN112786757B - AlGaInP light emitting diode chip structure

Info

Publication number: CN112786757B
Application number: CN202110197610.5A
Authority: CN
Inventors: 吕全江; 刘军林; 刘桂武; 乔冠军
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2021-12-21
Anticipated expiration: 2041-02-22
Also published as: CN112786757A

Abstract

The invention relates to the field of semiconductor light-emitting devices, in particular to an AlGaInP light-emitting diode structure. The invention adopts N-type Ga_xIn_1‑xP ohmic contact layer (x is more than or equal to 0.4 and less than or equal to 0.6) for replacing N type GaAs ohmic contactAnd (3) a layer. Ga_xIn_1‑xThe P (x is more than or equal to 0.4 and less than or equal to 0.6) material has good lattice matching with the GaAs substrate, larger forbidden band width, better transparency to red light and good selective corrosivity with the GaAs substrate, and a P-surface pattern can be seen in the chip manufacturing process without a windowing process. In addition, through reasonable doping design, good ohmic contact can be well formed with the N electrode, and lower working voltage is guaranteed. In the epitaxial growth process, N-type Ga can be directly grown after the growth of the buffer layer_xIn_1‑xAnd a P ohmic contact layer (x is more than or equal to 0.4 and less than or equal to 0.6) is formed, and then an N type layer is grown, so that the process is simpler and has lower cost compared with the prior process.

Description

AlGaInP light emitting diode chip structure

Technical Field

The invention relates to the field of semiconductor light-emitting devices, in particular to an AlGaInP light-emitting diode structure.

Background

Semiconductor Light Emitting Diodes (LEDs) are recognized as a new generation of illumination sources. AlGaInP materials lattice-matched to gallium arsenide substrates can cover visible wavelengths ranging from 560nm to 650nm, and are excellent materials for making red to yellow-green LEDs. AlGaInP light emitting diodes have important applications in the display field, such as full color screen displays, automotive lamps, traffic lights, etc. With the continuous improvement of the luminous efficiency of InGaN-based yellow LED, a pure LED illumination light source (without fluorescent powder, white light synthesized by multi-primary-color LED) reaches the practical level. In pure LED lighting sources (especially low color temperature LED light sources), red light has an irreplaceable role, and the demand will increase greatly.

In recent years, the growth technology of AlGaInP light emitting diode epitaxial materials has been greatly improved, and the internal quantum efficiency of the red light band can reach more than 90%. However, the chip structure without peeling off the gaas substrate has low electro-optic conversion efficiency, typically less than 10%, due to absorption and total reflection loss of the gaas substrate. In order to eliminate the influence of substrate absorption and slow down total reflection on the electro-optic conversion efficiency and improve the light extraction efficiency of the AlGaInP light-emitting diode, a thin film type chip structure for stripping a gallium arsenide substrate is invented. The manufacturing process of the film type AlGaInP light-emitting diode chip comprises the following steps: firstly, growing an AlGaInP light-emitting diode epitaxial film comprising a buffer layer, a corrosion stop layer, an N-type GaAs ohmic contact layer, an N-type layer, a light-emitting layer, a P-type layer and a high-resistance semiconductor layer on a gallium arsenide substrate in sequence; the AlGaInP light emitting diode epitaxial material is bonded to a substrate with a reflecting structure, such as silicon, germanium and metal, with a P surface downward, a gallium arsenide substrate and a buffer layer are removed, then a corrosion stop layer is corroded, an N electrode is manufactured on an N-type GaAs ohmic contact layer, finally the N-type GaAs ohmic contact layer outside the N electrode is corroded, and surface roughening is performed on the N-type layer to reduce total reflection loss of a light output surface, so that the thin-film chip structure can greatly improve the electro-optic conversion efficiency of the AlGaInP light emitting diode and reach 30-60%.

A typical structure of a conventional thin film AlGaInP light emitting diode chip is shown in fig. 1, which mainly includes: the LED chip comprises a substrate, a bonding metal layer, a reflecting metal layer, a dielectric layer, a P-type contact electrode, a P-type layer, a light emitting layer, an N-type GaAs ohmic contact layer, an N electrode and a P electrode.

In the conventional chip structure of thin-film AlGaInP light-emitting diode, in order to avoid absorption of light emitted from the light-emitting layer 106, it is generally required that each layer is made of a material having a forbidden band width larger than the energy of light-emitting photons emitted from the light-emitting layer, such as N-type layer (Al)_xGa_1-x)_0.5In_0.5P (x is more than or equal to 0.1 and less than or equal to 0.5) material. However (Al)_xGa_1-x)_0.5

In_0.5P (x is more than or equal to 0.1 and less than or equal to 0.5) is difficult to make ohmic contact with the N electrode, so that an N-type GaAs ohmic contact layer is arranged above an N-type layer in the conventional structure to realize good ohmic contact with the N electrode, and the problem of ohmic contact of the N electrode is well solved. However, GaAs has a forbidden band width of only 1.42eV (corresponding to the infrared band), for (Al)_xGa_1-x)_0.5In_0.5The P (x is more than or equal to 0 and less than or equal to 0.3) light emitted by the luminous layer has very strong absorption to the light in the yellow-green light to red light wave band. The N-type GaAs ohmic contact layer is located in the region with the N electrode, accounts for 10-40% of the total area of the chip in film type AlGaInP light-emitting diode chip structures with different sizes, and has strong absorption on light emission of the light-emitting layer, so that the light-emitting efficiency of the film type AlGaInP light-emitting diode chip is reduced. In other words, the conventional chip structure of the thin-film AlGaInP light emitting diode has a contradiction between the N-type ohmic contact and the light extraction efficiency of the chip.

Meanwhile, because the N-type GaAs ohmic contact layer and the GaAs substrate are made of the same material, in the process of manufacturing the chip etching substrate, the N-type GaAs ohmic contact layer and the GaAs substrate are removed together, so a layer of etching stop layer is usually introduced between the N-type GaAs ohmic contact layer and the GaAs substrate, and the etching stop layer is not etched when the GaAs substrate is etched, so that the N-type GaAs ohmic contact layer below the etching stop layer is not etched. And etching off the corrosion stop layer before preparing the N electrode to expose the N-type GaAs ohmic contact layer, preparing the N electrode on the N-type GaAs ohmic contact layer and carrying out subsequent process. At this time, since the N-type GaAs ohmic contact layer is on the uppermost layer and is opaque to visible light, the pattern of the N-side is difficult to align with the P-side, and a portion of the N-type GaAs ohmic contact layer needs to be etched away by one step of photolithography at a proper position, so that the pattern of the P-side can be seen (commonly referred to as a windowing process). Therefore, due to the existence of the N-type GaAs ohmic contact layer, an additional corrosion stop layer needs to be grown in the epitaxial process, and a plurality of photoetching, corrosion and other processes are needed in the chip manufacturing process, so that the manufacturing complexity and the production cost are increased.

Disclosure of Invention

In order to solve the problems, the invention provides a novel structure of an AlGaInP light-emitting diode, which can improve the light extraction efficiency of the AlGaInP light-emitting diode, reduce the process complexity in the epitaxial growth and chip manufacturing processes and effectively reduce the production cost.

An AlGaInP light emitting diode structure is shown in fig. 2, which comprises the following components from bottom to top: p electrode, base plate, bonding metal layer, reflection metal layer, dielectric layer, P type contact electrode, P type layer, luminescent layer, N type ohmic contact layer, N electrode, its characterized in that: the N-type ohmic contact layer is Ga_xIn_1-xX is more than or equal to 0.4 and less than or equal to 0.6, and the concentration of doped Si is 0.1 multiplied by 10¹⁸～10×10¹⁸cm^-3。

The invention is characterized in that: using N-type Ga_xIn_1-xThe P ohmic contact layer (x is more than or equal to 0.4 and less than or equal to 0.6) replaces the N-type GaAs ohmic contact layer. Ga_xIn_1-xThe P (x is more than or equal to 0.4 and less than or equal to 0.6) material has good lattice matching with the GaAs substrate, has larger forbidden band width and has red light resistanceThe transparent film has better transparency and has better selective corrosivity with GaAs, and a P-surface pattern can be seen in the chip manufacturing process without a windowing process. In addition, through reasonable doping design, good ohmic contact can be well formed with the N electrode, and lower working voltage is guaranteed. In the epitaxial growth process, N-type Ga can be directly grown after the growth of the buffer layer_xIn_1-xAnd a P ohmic contact layer (x is more than or equal to 0.4 and less than or equal to 0.6) is formed, and then an N type layer is grown, so that the process is simpler and has lower cost compared with the prior process.

Therefore, the N-type GaAs ohmic contact layer is removed, and the N-type Ga is adopted_xIn_1-xThe P ohmic contact layer (x is more than or equal to 0.4 and less than or equal to 0.6) solves the contradiction between the N ohmic contact and the chip light-taking efficiency caused by the N GaAs ohmic contact layer adopted by the traditional film type AlGaInP light-emitting diode chip structure, obtains the chip light-taking efficiency higher than that of the traditional structure while obtaining the good N ohmic contact, simultaneously reduces the process complexity in the epitaxial growth and chip manufacturing process, and reduces the production cost.

Drawings

FIG. 1 is a schematic structural diagram of a typical AlGaInP light-emitting diode thin-film chip;

illustration of the drawings: 100-substrate, 101-bonding metal layer, 102-reflection metal layer, 103-dielectric layer, 104-P surface contact electrode, 105-P type layer, 106-luminous layer, 107-N type layer, 108-N type GaAs ohmic contact layer, 109-N electrode and 110-P electrode;

FIG. 2 is a schematic diagram of a thin film AlGaInP light emitting diode chip structure according to the present invention;

illustration of the drawings: 200-substrate, 201-bonding metal layer, 202-reflection metal layer, 203-dielectric layer, 204-P surface contact layer, 205-P type layer, 206-light emitting layer, 207-N type layer, 208-N type ohmic contact layer, 209-N electrode and 210-P electrode.

Detailed Description

The following description of the patent refers to the field of 'electric digital data processing'.

Fig. 2 is a schematic diagram of an AlGaInP light emitting diode chip according to the present invention, the thin film chip is composed of the following parts from bottom to top: the light-emitting diode comprises a P electrode 210, a substrate 200, a bonding metal layer 201, a reflecting metal layer 202, a dielectric layer 203, a P-surface contact electrode 204, a P-type layer 205, a light-emitting layer 206, an N-type layer 207, an N-type ohmic contact layer 208 and an N electrode 209.

a) Providing a GaAs substrate

b) Epitaxially growing a buffer layer and N-type Ga on the substrate in sequence_xIn_1-xA P ohmic contact layer (x is more than or equal to 0.4 and less than or equal to 0.6), an N type layer, a light emitting layer and a P type layer. Wherein the N-type ohmic contact layer is Ga_xIn_1-xP (x is more than or equal to 0.4 and less than or equal to 0.6) and Si-doped concentration is 0.1 multiplied by 10¹⁸～10×10¹⁸cm^-3. Preferably, the N-type ohmic contact layer adopts Ga_xIn_1-xP (x is more than or equal to 0.48 and less than or equal to 0.52). The light-emitting layer 206 has a multi-quantum well structure, and the well and barrier are (Al)_xGa_1-x)_0.5In_0.5P(0≤x≤0.3)、(Al_xGa_1-x)_0.5In_0.5P (x is more than or equal to 0.4 and less than or equal to 0.6). The N-type layer 207 is (Al)_xGa_1-x)_0.5In_0.5P(0.1≤x≤0.5)。

c) After the epitaxial material grows, the epitaxial material is transferred to a substrate by using a conventional die preparation process (metal evaporation, photoetching, corrosion, bonding, alloying and cutting) to prepare an AlGaInP light-emitting diode thin-film chip with an N-surface light emitting function, wherein the substrate 200 adopts Si, Ge or Cu.

d) And after the chip is prepared, the tube cores are separated by using a cutting process, the voltage, the brightness and the wavelength are graded according to point measurement indexes, and the tube cores are classified, packaged and then put in storage.

Claims

1. An AlGaInP light emitting diode chip structure comprises the following components from bottom to top: p electrode, base plate, bonding metal layer, reflection metal layer, dielectric layer, P type contact electrode, P type layer, luminescent layer, N type ohmic contact layer, N electrode, its characterized in that: the N-type ohmic contact layer is Ga_xIn_1-xX is more than or equal to 0.4 and less than or equal to 0.6, and the concentration of doped Si is 0.1 multiplied by 10¹⁸cm^-3～10×10¹⁸cm^-3。

2. As claimed in claim 1The AlGaInP light-emitting diode chip structure is characterized in that: the N-type ohmic contact layer is Ga_xIn_1-xP，0.48≤x≤0.52。

3. The AlGaInP light emitting diode chip structure of claim 1, wherein: the luminescent layer adopts a multi-quantum well structure, and the wells and barriers are respectively (Al)_xGa_1-x)_0.5In_0.5P，0≤x≤0.3；(Al_xGa_1-x)_0.5In_0.5P，0.4≤x≤0.6。

4. The AlGaInP light emitting diode chip structure of claim 1, wherein: the N-type layer is (Al)_xGa_1-x)_0.5In_0.5P，0.1≤x≤0.5。