CN101867002A

CN101867002A - Novel semiconductor light-emitting diode

Info

Publication number: CN101867002A
Application number: CN 201010183993
Authority: CN
Inventors: 廖翊韬; 云峰
Original assignee: CHANGZHOU MEIJIAWEIYE PHOTO-ELECTRICITY SCIENTIFIC AND TECHNICAL Co Ltd
Current assignee: CHANGZHOU MEIJIAWEIYE PHOTO-ELECTRICITY SCIENTIFIC AND TECHNICAL Co Ltd
Priority date: 2010-05-27
Filing date: 2010-05-27
Publication date: 2010-10-20

Abstract

The invention relates to a novel semiconductor light-emitting diode, which comprises a substrate, a buffer layer, an N-type layer, an active layer, an electronic barrier layer, a P-type layer and a P-type contact metal layer. The P-type layer, the electronic barrier layer, the active layer and the like are penetrated through etching; an N-type layer material is exposed to one side of a P-type material directly, and an N-type contact metal and an electrode are covered on an exposed area, so that the diffusion of transverse current in the N-type layer is enhanced; and simultaneously, a P-type metal covers an integral P-type semiconductor layer, and an LED emits light from the bottom surface of the substrate. Through the improvement, the transverse diffusion distance of the current in LED devices is shortened substantially, uneven distribution of current density in the LED devices due to current congestion is prevented, so that the LED devices emit the light uniformly, and the shading effect of a P-type electrode is eliminated.

Description

A kind of novel semiconductor light-emitting diode

Technical field

The present invention relates to a kind of semiconductor light-emitting-diode.

Background technology

Semiconductor light-emitting-diode (Light Emitting Diode is hereinafter to be referred as LED) is a kind of light emitting semiconductor device, utilizes gallium nitride series compound light-emitting material, causes that photon is compound and luminous under forward voltage.LED directly sends white and various glories, and its luminescence process comprises that the charge carrier under the forward bias injects, recombination radiation is luminous and effective extraction of luminous energy.

Yet, the LED of main flow design at present all adopts N type and P type electrode branch to be in the etching ledge structure (Mesa-etch structure) at two ends, the LED left and right sides, its electronics injects and diffusion is restricted, and causes the LED luminous efficiency to reduce luminosity inhomogeneous (as shown in Figure 1).Under the high current density injection condition, it is congested that electric current appears in the zone of close N type electrode easily, causes the too high even whole LED component failure of local temperature.

For solving the electric current congestion problems, solid-state physics present situation communication magazine (Physica StatusSolidi C) in the 6th phase in 2008, the people such as Hertkorn of Germany E Mu university have proposed a kind of novel epitaxial layer structure, use gallium nitride, the superlattice structure of aluminium nitride and aluminium gallium nitride alloy compound semiconductor (superlattice), and the distinctive two-dimensional electron gas building-up effect of this structure strengthens the transverse current diffusion of N type layer.But, because it is bigger to introduce resistivity, being difficult for the aluminum nitride epitaxial layer of doping, this structure will increase the vertical direction resistance of LED matrix, increase forward voltage and also lower efficiency and reliability.

Summary of the invention

In order to overcome the defective of existing LED device, the invention provides that a kind of bright dipping is even, luminous efficiency is high, the reliable novel semiconductor light-emitting diode of electrode, solved LED device current congestion problems, solved simultaneously that amount of light that the P type electrode light-shading effect because of LED causes reduces and problem such as electrode reliability reduction.

Concrete technical scheme of the present invention is: a kind of novel semiconductor light-emitting diode, comprise compound successively substrate, resilient coating, N type layer, active layer, electronic barrier layer, P type layer, P type contact metal layer, wherein at P type contacting metal laminar surface, at least form the groove of a groove depth to substrate approach by methods such as etchings to N type layer, sidewall is provided with insulating barrier around the described groove, also be provided with N type contact metal layer, described N type contact metal layer is compounded in P type contacting metal laminar surface at interval by insulating barrier, and extends to both with groove to N type layer and directly contact connection.

The present invention penetrates P type layer, electronic barrier layer, active layer etc. by etching, N type layer material directly is exposed to P-type material one side, and at exposed region covering N type contacting metal and electrode, thereby strengthen the transverse current diffusion in the N type layer, P type metal covers whole p type semiconductor layer simultaneously, and LED is from the substrate surface bright dipping.By above-mentioned improvement: the present invention can shorten the transverse diffusion distance of electric current in the LED device significantly, has avoided the congested LED device current density distribution inequality that causes of electric current, and (particularly chip area is greater than 1mm to make the LED device ²LED) bright dipping is more even, and eradicated the light-shading effect of P type electrode.Simultaneously, avoided the concentrated LED device heat radiation difficulty that causes of the congested amount of localized heat of bringing of electric current, problems such as luminous efficiency and electrode reliability reduction.

In addition, because LED bright dipping part surface no longer covers metal electrode, for fluorescent material (Phosphor) spin coating in the follow-up white light LEDs processing procedure provides convenience, particularly can be directly at substrate surface composite fluorescence bisque.

Active layer described in the present invention comprises at least one group of combination that is formed by quantum potential barrier layer and quantum well layer.Wherein, the thickness in monolayer of described potential barrier layer and quantum well layer in 1 nanometer between 100 nanometers.

As to further research of the present invention, described N type layer thickness is between 100 nanometers to 100 micron; Further being expressed as described N type layer thickness is preferably between 1 micron to 100 microns.

Described electronic barrier layer thickness in 1 nanometer between 500 nanometers.

Described P type layer is made by nitride series compound semiconductor, and its thickness is between 10 nanometers to 10 micron.

Described groove floor sectional width is in 10 nanometers to 10, between 000 nanometer.

Description of drawings

The invention will be further described below in conjunction with drawings and Examples.

Fig. 1 is typical traditional etching stepped ramp type LED structure.

Fig. 2 is a LED structure chart of the present invention.

Wherein, 11 is substrate; 12. resilient coating; 13.N type layer; 14. active layer; 15. electronic barrier layer; 16 is P type layer; 17. be phosphor powder layer; 18 is the quantum potential barrier layer; 19 is the quantum well layer; 201.N type contact metal layer; 202.N type thick electrode; 203.P type contact metal layer; 204.P type thick electrode; 205. insulating barrier.

Embodiment

As shown in Figure 2: the present invention relates to a kind of novel semiconductor light-emitting diode, comprise compound successively phosphor powder layer 17, substrate 11, resilient coating 12, N type layer 12, active layer 14, selecting thickness is 10 nanometers, the electronic barrier layer 15 of 100 nanometers or 200 nanometers, selecting thickness is 10 nanometers, the P type layer 16 of 1 micron or 8 microns, P type contact metal layer 203, P type contact metal layer 203 and by insulating barrier 205 N type contact metal layer 201 at interval, carry out etching in the part on the P of LED device type layer 16 surface and form three grooves, it penetrates P type layer 16 respectively, active layer 14 and part N type layer 13, thereby make N type layer 13 material surface be exposed to P-type material one side, the gallium nitride based material of described N type layer is In _xAl _yGa _1-x-yN (0≤x≤1,0≤y≤1,0≤x+y≤1), and the ratio of x and y can be selected arbitrarily according to the optical wavelength that goes out of LED design.Evaporation contact metal layer 203 and electrode on P type layer 16, metal material is: the alloy of nickel, gold, and be complete covering P type layer 13.At the N type layer region evaporation contact metal layer and the electrode that expose, material is: the alloy of titanium, aluminium, gold, vanadium.N type contact metal layer 201 does not contact mutually with P type contact metal layer 203, electrode and active layer 14, electronic barrier layer 15, P type layer 16, its interface is isolated by insulating barrier 205, the part concave surface that this insulating barrier forms when covering N type layer material etching simultaneously and whole sidewall, insulating layer material is silicon dioxide or silicon nitride.

In above-mentioned, the chosen material of the substrate 11 of LED is: aluminium nitride, gallium nitride (GaN) or silicon (Si), carborundum (SiC) or lanthanum aluminate (LiAlO ₃) or sapphire (Al ₂O ₃) a kind of, selected substrate is transparent in LED goes out optical wavelength range, thereby and can comprise patterned surface texture and improve light extraction efficiency and reduce dislocation density.

Resilient coating 12 is used to cushion the stress effect that the lattice mismatch of substrate and gallium nitride based material causes, improves the N type layer 13 of subsequent growth, the crystal mass of active layer 14 and P type layer 16.

Active layer 14 comprises three groups of quantum potential barrier layer 18 and lower quantum well layer 19 combination of bandwidth that wavelength bandwidth is higher, and between 100 nanometers, present embodiment is selected 10 nanometers, 50 nanometers or 70 nanometers to its thickness in monolayer in 1 nanometer; Above-mentioned each material layer all can be made of the compound semiconductor of nitride, In _xAl _yGa _1-x-yN (0≤x≤1,0≤y≤1,0≤x+y≤1), and the ratio of x and y can be selected arbitrarily according to the optical wavelength that goes out of LED design.The semiconductor bandwidth of N type layer 13 and P type layer 16 is higher than the semi-conducting material bandwidth of active layer, above-mentioned layers of material all can mix as required, the material that can mix comprises silicon (Si), magnesium (Mg) etc., and its doping way comprises continuous doping and discontinuous doping etc.In order to obtain higher electronics and hole concentration, also can utilize the built-in polarized electric field of nitride to mix.Also can comprise similar superlattice structure in the N type layer and be used for reducing dislocation density.

The thickness of N type layer 13 generally is controlled between 100 nanometers to 100 micron, thereby for groove etching subsequently reserves enough error spaces, present embodiment thickness is chosen as 1 micron, 10 microns, 20 microns, 50 microns.

In surperficial evaporation one deck P type contact metal layer 203 of P type layer 16 material, this semiconductor-Metal Contact is ohmic contact (Ohmic contact).This P type contact metal layer 203 can be the stack architecture of single metal or multiple metal.

The generation type of insulating barrier 205 comprises the use plasma reinforced chemical vapour deposition, and forms by lithographic procedures.

After insulating barrier 205 formed, in the N type contact metal layer 201 that its surface forms, itself and N type layer semi-conducting material were ohmic contact.This N type contacting metal 201 can be the stack architecture of single metal or multiple metal, includes but not limited to the alloy of titanium (Ti), aluminium (Al), gold (Au), vanadium (V).

Subsequently, expose P type contact metal layer 203, and form solder joint 204 on its surface by etching N type contact metal layer 201 and insulating barrier 205.Adopt the LED of this structure generally need carry out flip-chip packaged.

The present invention also can in some LED structures, can insert one deck hole blocking layer (not shown) according to the difference of wavelength in n type material layer and the active layer.

Above disclosed only is preferred embodiment of the present invention, can not limit interest field of the present invention with this certainly, and therefore the equivalent variations of being done according to the present patent application claim still belongs to the scope that the present invention is contained.

Claims

1. novel semiconductor light-emitting diode, comprise compound successively substrate, resilient coating, N type layer, active layer, electronic barrier layer, P type layer, P type contact metal layer, it is characterized in that: at P type contacting metal laminar surface, at least form the groove of a groove depth to substrate approach by methods such as etchings to N type layer, sidewall is provided with insulating barrier around the described groove, also be provided with a N type contact metal layer, described N type contact metal layer is compounded in P type contacting metal laminar surface at interval by insulating barrier, and with groove to N type layer extending to both directly contact connection.

2. semiconductor light-emitting-diode according to claim 1 is characterized in that: also comprise the phosphor powder layer that is compounded in substrate surface.

3. semiconductor light-emitting-diode according to claim 1 is characterized in that: described active layer comprises one group of combination that is formed by quantum potential barrier layer and quantum well layer at least.

4. semiconductor light-emitting-diode according to claim 3 is characterized in that: the thickness in monolayer of described potential barrier layer and quantum well layer in 1 nanometer between 100 nanometers.

5. semiconductor light-emitting-diode according to claim 1 is characterized in that: described N type layer thickness is between 100 nanometers to 100 micron.

6. semiconductor light-emitting-diode according to claim 5 is characterized in that: described N type layer thickness is between 1 micron to 100 microns.

7. semiconductor light-emitting-diode according to claim 1 is characterized in that: described electronic barrier layer thickness in 1 nanometer between 500 nanometers.

8. semiconductor light-emitting-diode according to claim 1 is characterized in that: described P type layer is made by nitride series compound semiconductor, and its thickness is between 10 nanometers to 10 micron.

9. semiconductor light-emitting-diode according to claim 1 is characterized in that: described groove floor sectional width is in 10 nanometers to 10, between 000 nanometer.

10. semiconductor light-emitting-diode according to claim 1 is characterized in that: compound hole blocking layer between n type material layer and active layer.