Semiconductor light-emitting elements
Technical field
The invention provides a kind of semiconductor light-emitting elements, especially a kind of light-emitting diode with high-luminous-efficiency.
Background technology
Fig. 1 is existing light-emitting diode structure schematic diagram.As shown in Figure 1, existing light-emitting diode 10 consists predominantly of a substrate (substrate) 11, (Distributed Bragg Reflector, DBR) 12, one active layer (active layer), 13, one p type semiconductor layer 14, a P type electrode 15 and a N type electrode 16 are located at substrate 11 belows to a Bragg reflecting layer.Wherein, substrate 11 is N p type gallium arensidep (GaAs) substrate, and Bragg reflecting layer 12 then is made up of the reflection multilayer structure, uses the light of reflection directive substrate 11.Active layer 13 is made up of coating layer (upper cladding layer) on coating layer (lower cladding layer), an AlGaInP active layer and the P type AlGaInP under the N type AlGaInP (AlGaInP).In addition, p type semiconductor layer 14 is as an ohmic contact layer (ohmic contactlayer), its material can be that aluminum gallium arsenide, AlGaInP or gallium arsenide phosphide etc. are beneficial to the material that forms ohmic contact, and P type electrode 15 then is the metal electrode that engages (wire bonding) as routing with N type electrode 16.
Fig. 2 is another existing light-emitting diode structure schematic diagram.As shown in Figure 2, light-emitting diode 20 includes a substrate 21, a Bragg reflecting layer 22, a n type semiconductor layer 27, an active layer 23, a p type semiconductor layer 24, a P type electrode 25 and N type electrode 26.The manufacturing process of existing light-emitting diode 20 is prior to forming Bragg reflecting layer 22, n type semiconductor layer 27, active layer 23 and p type semiconductor layer 24 on the substrate 21, then carry out an etching step to expose part n type semiconductor layer 27, on p type semiconductor layer 24, form a P type electrode 25 then, the last N type electrode 26 that on the n type semiconductor layer 27 that exposes to the open air, forms again.Similarly, substrate 21 also is a N p type gallium arensidep substrate, and Bragg reflecting layer 22 then is made up of the reflection multilayer structure, uses the light of reflection directive substrate 21.Active layer 23 is made up of coating layer on coating layer, AlGaInP active layer and the P type AlGaInP under the N type AlGaInP.P type semiconductor layer 24 is as ohmic contact layer with n type semiconductor layer 27, and its material can be that aluminum gallium arsenide, AlGaInP or gallium arsenide phosphide etc. are beneficial to the material that forms ohmic contact.P type electrode 25 is the metal electrode that engages as routing with 26 at N type electrode.
Aforesaid light-emitting diode is when actual operation, because P type electrode and N type electrode can absorption portion by the light that active layer sent, make the light that active layer sent to be dissipated into fully in the external environment, and then reduce the luminous efficiency of whole light-emitting diode.
Summary of the invention
Main purpose of the present invention is to provide a kind of light-emitting diode with high-luminous-efficiency, to solve the problem that metal electrode in the above-mentioned existing light-emitting diode can absorb light source.
Main technical schemes of the present invention is: this semiconductor light-emitting elements includes a substrate, a N type electrode, an active layer, a p type semiconductor layer, a reflector and a P type electrode.Wherein N type electrode is covered in the first surface of substrate, and active layer is covered in the second surface of substrate, and p type semiconductor layer is covered on the active layer, and the reflector is positioned on the p type semiconductor layer and P type electrode covers the reflector.The reflector is one to have the metal level of high reflection efficiency.
Another technical scheme of the present invention is: this semiconductor light-emitting elements includes a substrate, a n type semiconductor layer, an active layer, a p type semiconductor layer, a N type electrode, one first reflector and a P type electrode.Wherein n type semiconductor layer is covered on this substrate, active layer cover part n type semiconductor layer, p type semiconductor layer is covered on this active layer, and N type electrode is positioned on the n type semiconductor layer of exposure, and first reflector is positioned on the p type semiconductor layer and P type electrode covers first reflector.And this semiconductor light-emitting elements more can comprise one second reflector, and between n type semiconductor layer and N type electrode, and first reflector and second reflector are a metal level with high reflection efficiency.
With respect to existing light emitting diode construction, light-emitting diode of the present invention has the reflector of high reflection efficiency, and therefore the light that can avoid active layer to send is absorbed by metal electrode, so that the light that active layer sends is fully utilized.
Description of drawings
The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments:
Fig. 1 is an existing light-emitting diode structure schematic diagram;
Fig. 2 is another existing light-emitting diode structure schematic diagram;
Fig. 3 is the structural representation of first embodiment of the invention;
Fig. 4 is the structural representation of second embodiment of the invention.
Embodiment
Embodiment one
As shown in Figure 3, light-emitting diode 30 includes substrate 31, Bragg reflecting layer 32, active layer 33, p type semiconductor layer 34, P type electrode 35, N type electrode 36 and reflector 38.The present invention is when making light-emitting diode 30, be on substrate 31, to form Bragg reflecting layer 32, active layer 33 and p type semiconductor layer 34 earlier in regular turn, then on the p type semiconductor layer 34 of part, form a reflector 38, and then on reflector 38, form a P type electrode 35, and form a N type electrode 36 in another surface of substrate 31.
Wherein, substrate 31 is an electric conducting material, for example N p type gallium arensidep (GaAs) or gallium nitride (GaN), and Bragg reflecting layer 32 then is made up of the reflection multilayer structure, for example the catoptric arrangement that is formed by aluminium arsenic (AlAs) and GaAs (GaAs) crossover is used the light that reflects directive substrate 31.The structure of active layer 33 can be homostyructure (homostructure), single heterojunction structure (single heterostructure), double-heterostructure (double heterostructure, DH) or multiple quantum trap (multiple quantum well, MQW), then it can be made up of coating layer (upper cladding layer) on coating layer (lower cladding layer), AlGaInP active layer and the P type AlGaInP under the N type AlGaInP (AlGaInP) if active layer 33 is by double-heterostructure.Because all types of structures of active layer belong to the scope of existing skill, and non-inventive features of the present invention place, no longer add to give unnecessary details in this.In addition, p type semiconductor layer 34 is intended for ohmic contact layer (ohmic contact layer), it mainly is made up of multilayer P type III-V compounds of group, for example p type semiconductor layer 34 can be made up of magnesium or zinc doping gallium nitride (Mg or Zn doped GaN), and it can also be that aluminum gallium arsenide, AlGaInP or gallium arsenide phosphide etc. are beneficial to the material that forms ohmic contact.P type electrode 35 then is in follow-up encapsulation procedure with N type electrode 36, engages the metal electrode of (wire bonding) as routing.
It should be noted that reflector 38 of the present invention is one to have metal, alloy or other electric conducting material of high reflection efficiency, for example silver (Ag), aluminium (Al), gold (Au), chromium (Cr), platinum (Pt) or rhodium (Rh) etc., and it can be the single or multiple lift structure.Reflector 38 mainly is to be used for the light that reflex layer 33 sends, so that the light that active layer 33 sends diffuses in the external environment by other position of light-emitting diode 30, and then the light of effectively avoiding active layer 33 to send is absorbed by P type electrode 35.And inclined-plane or curved-surface structure that reflector of the present invention 38 and p type semiconductor layer 34 contacted surfaces also can be designed to a matsurface or have at least one specific reflection angle are with the reflecting effect of strengthening reflector 38 and avoid taking place the absorbed phenomenon of light.In addition, reflector 38 of the present invention is also replaceable to be a scattering layer, a transparent conductive material that includes a plurality of scattering mediums (diffuser) for example, be used for the light that partial reflection active layer 33 sends, reducing the phenomenon that light is absorbed by P type electrode 35, and then improve the illumination effect of light-emitting diode 30.
Embodiment two
As shown in Figure 4, light-emitting diode 40 also includes substrate 41, Bragg reflecting layer 42, active layer 43, p type semiconductor layer 44, P type electrode 45, N type electrode 46, n type semiconductor layer 47, first reflector 48 and second reflector 49.The manufacturing process of light-emitting diode 40 is prior to forming Bragg reflecting layer 42, n type semiconductor layer 47, active layer 43 and p type semiconductor layer 44 on the substrate 41 in regular turn, follow the p type semiconductor layer 44 and the active layer 43 of etching part, to expose the n type semiconductor layer 47 of part.On without etched p type semiconductor layer 44 and the n type semiconductor layer 47 that exposes to the open air, form first reflector 48 and the P type electrode 45 and second reflector 49 and N type electrode 46 respectively subsequently.Wherein, this etch process can use Wet-type etching, dry-etching or the two is used alternatingly.In addition, first reflector 48 and second reflector 49 can be selected one or be made in light-emitting diode 40 simultaneously and manage in 40 according to the needs of design.
In second embodiment of the invention, substrate 41 is an insulating material, sapphire (sapphire) for example, and the material of Bragg reflecting layer 42, active layer 43 and p type semiconductor layer 44 is then with identical described in first embodiment.N type semiconductor layer 47 is intended for an ohmic contact layer, formed by multilayer N type III-V compounds of group, for example form by undoped gallium nitride (undoped GaN) and silicon-doped gallium nitride (Si doped GaN), but its can also to be aluminum gallium arsenide, AlGaInP or gallium arsenide phosphide etc. be beneficial to forms the material of ohmic contact.P type electrode 45 then is in follow-up encapsulation procedure with N type electrode 46, as the metal electrode of routing joint.
It should be noted that, first reflector 48 and second reflector 49 also are one and have the single or multiple lift structure of metal, alloy or other electric conducting material of high reflection efficiency, for example silver-colored (Ag), aluminium (Al), gold (Au), chromium (Cr), platinum (Pt) or rhodium (Rh) etc., be used for the light that reflex layer 43 sends, so that the light that active layer 43 sends diffuses in the external environment by other position of light-emitting diode 40, and then the light of effectively avoiding active layer 43 to send is absorbed by P type electrode 45 and N type electrode 46.And inclined-plane or curved-surface structure that each reflector 48,49 and each type semiconductor layer 44,47 contacted surfaces also can be designed to a matsurface or have at least one specific reflection angle are to strengthen the reflecting effect in each reflector 48,49.In addition, reflector 48,49 is also replaceable to be a scattering conductive layer, reducing the phenomenon that light is absorbed by P type electrode 45 and N type electrode 46, and then improves the illumination effect of light-emitting diode 40.