CN1319183C - Semiconductor luminessent device and method for manufacturing semiconductor luminescent device - Google Patents
Semiconductor luminessent device and method for manufacturing semiconductor luminescent device Download PDFInfo
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- CN1319183C CN1319183C CNB2003101015307A CN200310101530A CN1319183C CN 1319183 C CN1319183 C CN 1319183C CN B2003101015307 A CNB2003101015307 A CN B2003101015307A CN 200310101530 A CN200310101530 A CN 200310101530A CN 1319183 C CN1319183 C CN 1319183C
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Abstract
A light emitting layer 4 composed of a single or a plurality of semiconductor layers is laminated on a nondope type, weak p-type, or n-type first semiconductor substrate. On the light emitting layer 4, n-type semiconductor layers 5-7 composed of a single layer or a plurality of layers are laminated. On the surface of the n-type semiconductor layer 7, a second semiconductor substrate 8 transparent to the wavelength of emitted light from the light emitting layer 4 is formed. Then, the first semiconductor substrate is removed. On the plane exposed by removal of the first semiconductor substrate, a translucent electrode layer 9 transparent to the wavelength of emitted light from the light emitting layer is formed.
Description
Background of invention
The method that the present invention relates to light emitting semiconductor device and be used for making this light emitting semiconductor device.
In recent years, in the light emitting semiconductor device field, light-emitting diode (LEDs) is widely used in optical communication, LED information display screen or the like.It is important having high brightness for these light-emitting diodes, the brightness of light-emitting diode, and just external quantum efficiency determines that by internal quantum and light extraction efficiency wherein, it is bigger that light extraction efficiency is influenced by component structure.
In light-emitting diode, using increases light extraction efficiency for the transparent substrate of light emitted wavelength.This is because use only can make a branch of light that is emitted to upper surface go out for the opaque substrate of light wavelength, can make multi-beam not only from upper surface and use for the transparent substrate of light emitted wavelength, and go out from four sides.In addition, a branch of light that reflects on lower surface can be gone out from upper surface and side equally.The infrarede emitting diode that this method is applied to be made up of the InGaAsP base semiconductor material, the ruddiness of forming by the AlGaAs base semiconductor material and infrarede emitting diode, the Yellow light emitting diode of forming by the GaAsP base semiconductor material, green light LED of forming by the GaP base semiconductor material or the like.
Has manufacture method as manufacturing for the AlGaInP based light-emitting diode of the transparent substrate of light emitted wavelength, as everyone knows, by a kind of method of forming by the following step, comprise, shown in Figure 10 A, epitaxial growth n type semiconductor layer 112 on to the opaque n type of light emitted wavelength GaAs substrate 110, luminescent layer 114, and p-type semiconductor layer 116, to being placed on the p-type semiconductor layer 116, heat-treat to set up direct joint the between p type GaP substrate 120 and the p type semiconductor layer 116 for the transparent p type GaP substrate 120 of light emitted wavelength, and then, shown in Figure 10 B, remove n type GaAs substrate 110 (seeing the specification of Japan Patent No.3230638).
Equally, as everyone knows, the manufacture method of forming by the following step by another kind, comprise: shown in Figure 11 A, epitaxial growth n type semiconductor layer 212, luminescent layer 214, p type semiconductor layer 216 and p type GaP current-diffusion layer 218 on to the opaque n type of light emitted wavelength GaAs substrate 210 with about 50 μ m～100 μ m thickness; Shown in Figure 11 B, remove n type GaAs substrate 210; And then shown in Figure 11 C, heat-treat to set up direct joint the between n type semiconductor layer 212 and the n type GaP substrate 220 (see Japan speciallys permit disclose flat 6-302857) being placed on by removing n type GaP substrate 220 on the plane that step exposes.What notice is, if the thickness of p type GaP current-diffusion layer 218 is 50 μ m or littler, it is easy to cause breakage when wafer is operated, and if its thickness is 100 μ m or bigger, the growth duration elongated, make the manufacturing expense of light-emitting diode higher thus.Therefore, consider the growth duration and remove the GaAs substrate mechanical strength of wafer afterwards that the thickness of p type GaP current-diffusion layer 218 is set to about 50 μ m to 100 μ m.
As everyone knows, also has the another kind of manufacture method of forming by the following step, comprise: shown in Figure 12 A, epitaxial growth p type GaAs resilient coating 311, p type AlGaAs current-diffusion layer 312, p type cover layer 3 13, active layer 314, n type cover layer, n type intermediate layer 316 on to the opaque n type of light emitted wavelength GaAs substrate 310, and n type GaP layer 317, shown in Figure 12 B, form n type GaP substrate 318 in the above, and then, remove n type GaAs substrate 310 (seeing the open 2000-196139 of Japan's special permission).
Yet, said method has caused a problem, be included near p type substrate 120,220 of luminescent layer (or active layer) and the p type dopant in the p type current-diffusion layer 218,312, for example Zn and Mg, total amount big, so that the thermal process that is subjected in crystal growth and the direct bonding operation makes p type diffuse dopants enter luminescent layer (or active layer), causes the brightness of internal quantum reduction and device to reduce.Especially, with GaAs substrate lattice coupling and can realize in the AlGaInP based light-emitting diode of low-resistivity, unique a kind of known to having used for the transparent Al of light emitted wavelength
xGa
1-xAs (0.5≤x≤1).At A1
xGa
1-xAmong the As (0.5≤x≤1), the diffusion coefficient of Zn, Mg or the like is big, makes that like this this problem is more thorny.
In addition, as mentioned above, n type current-diffusion layer 218,312 grows into a few μ m or bigger thickness usually, and other coating growth becomes a few μ m or littler thickness, causes the problem that frequency of maintenance increases and productivity descends of growth apparatus like this.Because attended operation includes the generation of poisonous gas, equally from safety point of view, less frequency of maintenance is more suitable.
Summary of the invention
Primary goal of the present invention provides and can suppress p type diffuse dopants and enter luminescent layer (or active layer) realizing high brightness and can reduce the light emitting semiconductor device of growth apparatus frequency of maintenance, and the method for making this light emitting semiconductor device is provided.
In order to realize above-mentioned target, a kind of method that is used for making light emitting semiconductor device of the present invention is provided, comprising:
Luminescent layer is layered in not doping type, weak p type, and perhaps on n type first Semiconductor substrate, this luminescent layer is made up of the single or multiple lift semiconductor layer;
The n type semiconductor layer is layered on the luminescent layer, and this n type semiconductor layer is made up of single or multiple lift;
Form second Semiconductor substrate at n N-type semiconductor N laminar surface, this second Semiconductor substrate is transparent for the light emitted wavelength of luminescent layer;
Remove first Semiconductor substrate then; And
Form transparent electrode layer on the plane that first Semiconductor substrate exposed removing, this transparent electrode layer is transparent for the light emitted wavelength of luminescent layer.
What notice is that the what is called of first Semiconductor substrate " weak p type " is meant that p type diffuse dopants enters the negligible basically p type of level of luminescent layer (or active layer).
According to the method for making light emitting semiconductor device of the present invention, made light emitting semiconductor device, comprise being separately positioned on above the luminescent layer and the following transparent electrode layer and second Semiconductor substrate that both are all transparent for the light emitted wavelength of luminescent layer.Making light send from the upper surface of device and side like this becomes possibility, has increased light extraction efficiency with using to compare for the situation of the light emitted opaque substrate of wavelength.In addition,, do not provide p type current-diffusion layer near luminescent layer yet, in high-temperature process, suppressed p type diffuse dopants and entered luminescent layer because p type substrate is not provided.And transparent electrode layer forms removing on the plane that first Semiconductor substrate exposed, and makes and spreads by transparent electrode layer in the course of the work by electric current, and inject luminescent layer equably.Thereby, increased internal quantum.As a result, the performance of light emitting semiconductor device is improved, and has realized high brightness.In the method for making light emitting semiconductor device of the present invention, do not provide current-diffusion layer equally, can reduce the thickness of epitaxially grown layer like this.Therefore, the frequency of maintenance that reduces growth apparatus becomes possibility, makes productivity ratio improve and the fail safe enhancing.
In one embodiment, before the method for making light emitting semiconductor device further is included in and is laminated to luminescent layer on first Semiconductor substrate, form the p type semiconductor layer on first Semiconductor substrate, wherein the p type semiconductor layer is formed the single or multiple lift that is different from first Semiconductor substrate by it and is formed.
More particularly, in this embodiment, the method for making light emitting semiconductor device may further comprise the steps:
In not doping type, weak p type, perhaps form the p type semiconductor layer on n type first Semiconductor substrate, this p type semiconductor layer is formed the single or multiple lift that is different from first Semiconductor substrate by it and is formed;
Luminescent layer is layered on the p type semiconductor layer, and this luminescent layer is made up of the single or multiple lift semiconductor layer;
The n type semiconductor layer is layered on the luminescent layer, and this n type semiconductor layer is made up of single or multiple lift;
Form second Semiconductor substrate at n N-type semiconductor N laminar surface, this second Semiconductor substrate is transparent for the light emitted wavelength of luminescent layer;
Remove first Semiconductor substrate then; And
Form transparent electrode layer on the plane that first Semiconductor substrate exposed removing, this transparent electrode layer is transparent for the light emitted wavelength of luminescent layer.
According to the method for making light emitting semiconductor device among this embodiment, make a kind of light emitting semiconductor device, this light emitting semiconductor device comprises and being separately positioned on above the luminescent layer and the following transparent electrode layer and second Semiconductor substrate that both are all transparent for the light emitted wavelength of luminescent layer.Making light send from the upper surface of device and side like this becomes possibility, has increased light extraction efficiency with using to compare for the situation of the light emitted opaque substrate of wavelength like this.In addition, because p type substrate is not provided near luminescent layer, in high-temperature process, has suppressed p type diffuse dopants and entered luminescent layer.And transparent electrode layer forms removing on the plane that first Semiconductor substrate exposed, and makes and spreads by transparent electrode layer in the course of the work by electric current, and inject luminescent layer equably.The result has increased internal quantum.In addition, the plane that forms transparency electrode is for by removing the plane that first Semiconductor substrate is exposed, just the plane of the p type semiconductor layer of being made up of single or multiple lift.Therefore, make the voltage drop on the interface between electrode and the semiconductor than directly forming voltage drop under the transparency electrode situation possibility that becomes more for a short time on the luminescent layer.As a result, the performance of light emitting semiconductor device is improved, and has realized high brightness.In the method for making light emitting semiconductor device of the present invention, do not provide current-diffusion layer equally, can reduce the thickness of epitaxially grown layer like this.Therefore, the frequency of maintenance that reduces growth apparatus becomes possibility, makes productivity increase and the fail safe enhancing.
First Semiconductor substrate is preferably the GaAs substrate.If first Semiconductor substrate is the GaAs substrate, just can make the high brightness semiconductor light emitters part of forming by the semiconductor layer made from GaAs substrate lattice matching materials.
Equally, luminescent layer is preferably by (Al
yGa
1-y)
zIn
1-zP (wherein 0≤y≤1,0≤z≤1) forms.If luminescent layer is by (Al
yGa
1-y)
zIn
1-zP forms, and just can make the high brightness semiconductor light emitters part of the light of emission 550nm～670nm wavelength.
Equally, second Semiconductor substrate is preferably the GaP substrate.Because GaP is transparent to the light beam that wavelength surpasses 550nm, second Semiconductor substrate increases light extraction efficiency for the GaP substrate makes and becomes possibility.
Equally, transparent electrode layer is preferably by indium oxide, tin oxide, indium tin oxide, zinc oxide, and magnesian at least a composition.If transparent electrode layer is by indium oxide, tin oxide, indium tin oxide, zinc oxide, and magnesian at least a composition, obtain 90% or higher visible light transmissivity become possibility.Therefore, it has further guaranteed the realization of high brightness.
In an embodiment who makes the light emitting semiconductor device method, second Semiconductor substrate forms by directly engaging.
Make in this embodiment in the method for light emitting semiconductor device, second Semiconductor substrate forms by directly engaging, and makes the thickness of second Semiconductor substrate can easily be set to level enough with regard to mechanical strength like this.
In an embodiment who makes the light emitting semiconductor device method, second Semiconductor substrate forms by epitaxial growth.
Make in this embodiment in the method for light emitting semiconductor device, second Semiconductor substrate forms by epitaxial growth, make second Semiconductor substrate can easily grow into target thickness like this, having eliminated thus provides additional step, for example polishes the necessity of second Semiconductor substrate.Therefore, and provide the situation of second Semiconductor substrate to compare, can simplify the manufacturing process of light emitting semiconductor device by direct joint.
In an embodiment who makes the light emitting semiconductor device method, the p type semiconductor layer has 1 * 10
18Cm
-3Or bigger and 1 * 10
19Cm
-3Or the carrier density between littler, and comprise for the transparent Al of the light emitted wavelength of luminescent layer
xGa
1-xAs layer (wherein 0.5≤x≤0.7).
According to the method for making light emitting semiconductor device among this embodiment, the p type semiconductor layer has 1 * 10
18Cm
-3Or bigger carrier density, make to be reduced in that the voltage drop on the interface becomes possibility between the transparent electrode layer that takes place in the device course of work and the p type semiconductor layer, cause the reduction of device operating voltage.What notice is that the p type semiconductor layer is for the transparent Al of the light emitted wavelength of luminescent layer
xGa
1-xAs layer (wherein 0.5≤x≤0.7) helps like this to prevent that light extraction efficiency from reducing.In addition, the upper limit of a carrier density that the p type semiconductor layer is given, just 1 * 10
19Cm
-3Or it is littler.At last, the thickness of restriction p type semiconductor layer has caused the qualification of p type dopant total amount within particular value, and making inhibition p type dopant diffuse into luminescent layer like this in high-temperature process becomes possibility.Therefore, the reduction of internal quantum can be inhibited.As a result, can prevent the reduction of light emitting semiconductor device brightness.
In an embodiment who makes the light emitting semiconductor device method, the p type semiconductor layer has 1 * 10
18Cm
-3Or bigger and 1 * 10
19Cm
-3Or the carrier density between littler, and comprise for the transparent (Al of the light emitted wavelength of luminescent layer
yGa
1-y)
zIn
1-zP layer (wherein 0≤y≤1,0≤z≤1).
According to the method for making light emitting semiconductor device among this embodiment, the p type semiconductor layer has 1 * 10
18Cm
-3Or bigger carrier density, the voltage drop on the interface (causing the reduction of device operating voltage) becomes possibility between transparent electrode layer and the p type semiconductor layer so that feasible minimizing occurs in the device course of work.What notice is that the p type semiconductor layer is for the transparent (Al of the light emitted wavelength of luminescent layer
yGa
1-y)
zIn
1-zP layer (wherein 0≤y≤1,0≤z≤1) helps like this to prevent that light extraction efficiency from reducing.In addition, the upper limit of a carrier density that the p type semiconductor layer is given, just 1 * 10
19Cm
-3Or it is littler.At last, the thickness of restriction p type semiconductor layer has caused the qualification of p type dopant total amount within particular value, and making inhibition p type dopant diffuse into luminescent layer like this in high-temperature process becomes possibility.Suppressed the reduction of internal quantum like this.As a result, the reduction of light emitting semiconductor device brightness can be prevented.In addition, the proportion of composing x of Al can be set at less than using Al
xGa
1-xAs (wherein 0.5≤x≤0.7) is as the proportion of composing x of the Al under the p N-type semiconductor N layer material situation.Therefore, under the less situation of the proportion of composing x of Al, the surface becomes and has oxidation resistance, makes that like this voltage drop on the interface becomes possibility between reduction transparent electrode layer and the p type semiconductor layer, reaches the increase of device benefit thus.
In an embodiment who makes the light emitting semiconductor device method, the p type semiconductor layer has 3 μ m or littler thickness.
Make in this embodiment in the method for light emitting semiconductor device, the p type dopant in the p type semiconductor layer for example total amount of Zn and Mg limits, and diffuses into luminescent layer so that suppress p type dopant in high-temperature process.Suppressed the reduction of internal quantum like this.As a result, the reduction of light emitting semiconductor device brightness can be prevented.
Light emitting semiconductor device of the present invention is provided, has comprised:
Luminescent layer of being made up of single or multiple lift and transparent electrode layer also carry out stackedly on a surface of GaP substrate with this order, this GaP substrate and transparent electrode layer are transparent for the light emitted wavelength of luminescent layer;
Wherein, the luminescent layer of being made up of single or multiple lift forms by directly being bonded on the GaP substrate;
On another surface of GaP substrate, provide first electrode; And
Provide second electrode so that be connected to transparent electrode layer.
Light emitting semiconductor device of the present invention comprises and being separately positioned on above the luminescent layer and following transparent electrode layer and GaP substrate that both are all transparent for the light emitted wavelength of luminescent layer.Making light send from the upper surface of device and side like this becomes possibility, and making has increased light extraction efficiency with using to compare for the situation of the light emitted opaque substrate of wavelength.In addition, when electric current passes through between first electrode and second electrode in the device course of work, spread through transparent electrode layer by electric current, and inject luminescent layer equably.Thereby, increased internal quantum.As a result, the performance of light emitting semiconductor device is improved, and has realized high brightness.In light emitting semiconductor device of the present invention, the transparent electrode layer dissufion current, so, the current-diffusion layer of the tens μ m thickness that comprise p type dopant needn't be provided near luminescent layer as in the conventional example, therefore having suppressed p type diffuse dopants enters luminescent layer.Equally, there has not been current-diffusion layer can reduce the thickness of epitaxially grown layer.Therefore, the frequency of maintenance that reduces growth apparatus becomes possibility, makes productivity increase and the fail safe enhancing.
Equally in one embodiment, light emitting semiconductor device further comprises the GaP layer between the luminescent layer that is arranged on the GaP substrate and is made up of single or multiple lift, and this GaP layer contacts with the GaP substrate.
Light emitting semiconductor device among this embodiment comprises the GaP layer between the luminescent layer that is arranged on the GaP substrate and is made up of single or multiple lift, this GaP layer contacts with the GaP substrate, has prevented like this because the generation that the VF (forward voltage) that the heterojunction between GaP layer and the GaP substrate causes raises.
Luminescent layer is preferably by (Al
yGa
1-y)
zIn
1-zP layer (wherein 0≤y≤1,0≤z≤1) is formed.If luminescent layer is by (Al
yGa
1-y)
zIn
1-zThe P layer is formed, and obtaining wavelength is the emission light of 550nm～670nm.
Transparent electrode layer is preferably by indium oxide, tin oxide, indium tin oxide, zinc oxide, and magnesian at least a composition.If transparent electrode layer is by indium oxide, tin oxide, indium tin oxide, zinc oxide, and magnesian at least a composition, can access 90% or higher visible light transmissivity.Therefore, it has further guaranteed the realization of high brightness.
According to light emitting semiconductor device among the present invention shown in the top description and the method for making this light emitting semiconductor device, suppress p type diffuse dopants and enter luminescent layer (or active layer) possibility that becomes, realized high brightness like this and reduced the frequency of maintenance of growth apparatus.
Description of drawings
Figure 1A, 1B and 1C are respectively end view, top view and the bottom view that shows light emitting semiconductor device in the first embodiment of the invention;
Fig. 2 is the end view of the light emitting semiconductor device manufacturing step of displayed map 1;
Fig. 3 is the end view of the light emitting semiconductor device manufacturing step of displayed map 1;
Fig. 4 is the end view of the light emitting semiconductor device manufacturing step of displayed map 1;
Fig. 5 is for showing the curve chart of external quantum efficiency and contact layer thickness dependence;
Fig. 6 A, 6B and 6C are respectively end view, top view and the bottom view that shows light emitting semiconductor device in the second embodiment of the invention;
Fig. 7 is the end view of the light emitting semiconductor device manufacturing step of displayed map 6;
Fig. 8 is the end view of the light emitting semiconductor device manufacturing step of displayed map 6;
Fig. 9 is the end view of the light emitting semiconductor device manufacturing step of displayed map 6;
Figure 10 A and 10B are for showing the cross-sectional view of the first conventional light emitting semiconductor device manufacturing step;
Figure 11 A, 11B and 11C are for showing the cross-sectional view of the second conventional light emitting semiconductor device manufacturing step; And
Figure 12 A, 12B and 12C are for showing the cross-sectional view of the 3rd conventional light emitting semiconductor device manufacturing step.
Embodiment
Embodiments of the invention will be in conjunction with the accompanying drawings now.
First embodiment
Figure 1A is for showing the end view of light emitting semiconductor device among first embodiment, and Figure 1B is the top view of light emitting semiconductor device, and Fig. 1 C is the bottom view of light emitting semiconductor device.
Shown in Figure 1A, light emitting semiconductor device is made up of n type GaP substrate 8, on the surface (end face among Figure 1A) of this n type GaP substrate 8 with bottom-up n type GaP protective layer (thickness 1 μ m) 7, the n type (Al of being sequentially set with
0.2Ga
0.8)
0.77In
0.23P intermediate layer (thickness 0.15 μ m) 6, n type (Al
0.7Ga
0.3)
0.5In
0.5P cover layer (thickness 1 μ m) 5, as p type quantum well active layer (quantum well active layer) 4, the p type (Al of luminescent layer
0.7Ga
0.3)
0.5In
0.5P cover layer (thickness 1 μ m) 3, and the transparent electrode layer of making by zinc oxide 9.In addition, another surface (bottom surface among Figure 1A) that the n type electrode of being made by AuSi 11 is arranged on GaP substrate 8 is as first electrode, and the bonding pad of making by Au (bonding pad) 10 on the surface of transparent electrode layer 9 (end face among Figure 1A) as second electrode.
Shown in Fig. 1 C, each all is processed to have the relatively little roundel of 30 μ m diameters n type electrode 11, and numerous roundels (in this example, 9 roundels are arranged to 3 row, 3 row altogether) are configured to matrix form in the bottom surface.Shown in Figure 1B, bonding pad 10 is processed to have the big relatively roundel of 120 μ m diameters, and this roundel is set at the centre of end face.
Though do not show in detail, quantum well active layer 4 has a kind of like this structure to make numerous in (Al
0.7Ga
0.3)
0.5In
0.5Barrier layer that P makes (barrier layer) and the trap layer of being made by GaInP (well layer) hocket stacked.By (Al
yGa
1-y)
zIn
1-zIt is the emission light of 550nm～670nm that P (wherein 0≤y≤1,0≤z≤1) formation quantum well active layer 4 provides wavelength as luminescent layer.
Light emitting semiconductor device is made with the following step.
I) at first, as shown in Figure 2, on 1 one surfaces of n type GaAs substrate (end face among Fig. 2), grow successively and stacked p type GaAs resilient coating (thickness 1 μ m) 2, p type (Al by metal organic chemical vapor deposition (MOCVD) as first Semiconductor substrate
0.7Ga
0.3)
0.5In
0.5P cover layer (thickness 1 μ m) 3, p type quantum well active layer 4, n type (Al
0.7Ga
0.3)
0.5In
0.5P cover layer (thickness 1 μ m) 5, n type (Al
0.2Ga
0.8)
0.77In
0.23P intermediate layer (thickness 0.15 μ m) 6, and n type GaP protective layer (thickness 1 μ m) 7.What notice is that except that the MOCVD method, growing method can comprise the whole bag of tricks for example MBE (molecular beam epitaxy) method and MOMBE (metal organic molecular beam epitaxy) method.
As p type (Al
0.7Ga
0.3)
0.5In
0.5When P cover layer 3 was grown, the thick part of 0.1 μ m of the cover layer 3 that contacts with GaAs resilient coating 2 is set to had 2 * 10
18Cm
-3Carrier density, and the thick part of 0.9 μ m of the cover layer 3 that contacts with p type quantum well active layer 4 is set to and has 5 * 10
17Cm
-3Carrier density.Equally, Zn is used as p type dopant, and Si is used as n type dopant.
Ii) secondly, the substrate under this state (wafer) surface is undertaken by polishing after the mirror finish, and the surface is carried out slight etching in order to thiosulfonic acid and hydrogen peroxide for basic etchant.Also preparation have high polishing surface n type GaP substrate 8 as second substrate, and the surface of this GaP substrate 8 is also carried out slight etching in order to thiosulfonic acid and hydrogen peroxide for the etchant on basis.Then, fully wash with pure water and drying after, as shown in Figure 3, make the mutually closely contact of these two substrates (wafer), and heating one hour under 800 ℃ temperature in hydrogen atmosphere.Like this, the surface (end face among Fig. 3) of the n type GaP protective layer 7 on the GaAs substrate 1 and a surface of n type GaP substrate 8, just two n type GaP layers have carried out direct joint.
Direct joint like this makes the thickness of easily setting n type GaP substrate 8 become possibility for level enough with regard to mechanical strength.
Iii) then, as shown in Figure 4, n type GaAs substrate 1 and p type GaAs resilient coating 2 are etched based on the etchant of ammonium and hydrogen peroxide by using.Then, the another side of n type GaP substrate 8 (bottom surface among Fig. 4) polishes to obtain target thickness.
Iv) then, shown in Figure 1A, the transparency electrode of being made by zinc oxide 9 is at p type (Al
0.7Ga
0.3)
0.5In
0.5The surface of P cover layer 3 forms, and further forms the bonding pad of being made by Au 10 in the above.At last, on the bottom surface of n type GaP substrate 8, form 9 circular n type electrodes of making by AuSi 11.
The external quantum efficiency of the light emitting semiconductor device of Zhi Zaoing is estimated under the condition that by the electric current between weld zone 10 and the n type electrode 11 is 20mA like this, and this external quantum efficiency is 11%.Under identical condition, the thickness that comprises of conventional configurations is that the external quantum efficiency of light emitting semiconductor device of the p type AlGaAs current-diffusion layer of 5 μ m is about 7.8%.This result confirms that the external quantum efficiency that the light emitting semiconductor device among this embodiment has than conventional light emitting semiconductor device improves about 1.5 times external quantum efficiency.
The improvement of device performance is owing to replacing p type substrate to use n type GaAs substrate 1 and n type GaP substrate 8 in the light emitting semiconductor device of this embodiment, and do not exist and contain Zn doped p type AlGaAs current-diffusion layer.Especially, in epitaxial growth operation that relates to high temperature and direct bonding operation process, the luminescent layer 4 that diffuses into of p type dopant Zn is reduced to minimum, similarly the consequential deterioration of internal quantum is reduced to minimum.In addition, because transparent electrode layer 9 helps the diffusion by electric current, electric current is injected luminescent layer equably, makes internal quantum increase.
In addition, light emitting semiconductor device comprises and is separately positioned on above the luminescent layer 4 and following transparent electrode layer 9 and GaP substrates 8, and both are all transparent for the light emitted wavelength of luminescent layer 4.This makes light send from the upper surface of device and side becomes possibility, has increased light extraction efficiency with using to compare for the situation of the light emitted opaque substrate of wavelength like this.Equally, GaP protective layer 7 contacts with GaP substrate 8, has prevented like this because the generation that the VF (forward voltage) that the heterojunction between GaP layer and the GaP substrate causes raises.
As a result, the performance of light emitting semiconductor device is improved and has reached high brightness.
In addition, the operating voltage of light emitting semiconductor device is 2.3V among this embodiment, is 20mA by electric current.At transparent electrode layer 9 and p type (Al
0.7Ga
0.3)
0.5In
0.5Be provided with in the middle of the P cover layer 3 and have 5 * 10
18Cm
-3The p type Al of carrier density and 0.2 μ m thickness
0.5Ga
0.5As layer (p type contact layer) makes becomes possibility at the situation decline low-work voltage that keeps light emitting semiconductor device brightness to 2.1V.
This is because have 5 * 10
18Cm
-3The p type contact layer of perhaps bigger carrier density makes in the device course of work and to reduce that the voltage drop on the interface becomes possibility between transparent electrode layer and the p type contact layer.
Above-mentioned p type contact layer is for the transparent Al of the light emitted wavelength of luminescent layer
xGa
1-xAs (wherein 0.5≤x≤0.7) layer is not so light extraction efficiency reduces.
In addition, by setting carrier density to 1 * 10 of p type contact layer
19Cm
-3Or littler, be 5 * 10
18Cm
-3More suitable, and the thickness that limits p type contact layer is within particular value, the total amount of p type dopant is limited, and making inhibition p type dopant diffuse into luminescent layer like this in high-temperature process becomes possibility.Therefore, the reduction of internal quantum can be inhibited.Thereby the reduction of internal quantum can be inhibited.Consequently, can prevent the reduction of light emitting semiconductor device external quantum efficiency (brightness).
More specifically, as shown in Figure 5, be 3 μ m with the thickness setting of p type contact layer or make being reduced in of external quantum efficiency (brightness) that limits light emitting semiconductor device become possibility within 10% forr a short time.
What notice is that being provided with of p type contact layer can be passed through in the initial growth step of MOCVD method at p type GaAs resilient coating 2 and p type (Al
0.7Ga
0.3)
0.5In
0.5Forming p type contact layer between the P cover layer (thickness 1 μ m) 3 realizes.
In this embodiment, do not provide p type current-diffusion layer, the thickness that can reduce epitaxially grown layer like this is to half of the thickness of the conventional configurations light emitting semiconductor device of the p type AlGaAs current-diffusion layer that contains 5 μ m thickness.Therefore, can make the frequency of maintenance of growth apparatus reduce half, make productivity increase and the fail safe enhancing.
Second embodiment
Fig. 6 A is for showing the end view of light emitting semiconductor device among second embodiment, and Fig. 6 B is the top view of light emitting semiconductor device, and Fig. 6 C is the bottom view of light emitting semiconductor device.
As shown in Figure 6A, light emitting semiconductor device comprises n type GaP substrate 29, on the surface (end face among Fig. 6 A) of this n type GaP substrate 29 with bottom-up n type GaP protective layer (thickness 1 μ m) 28, the n type (Al of being sequentially set with
0.2Ga
0.8)
0.77In
0.23P intermediate layer (thickness 0.15 μ m) 27, n type Al
0.5In
0.5P cover layer (thickness 1 μ m) 26, as p type quantum well active layer 25, the p type Al of luminescent layer
0.5In
0.5P cover layer (thickness 1 μ m) 24, p type (Al
0.5Ga
0.5)
0.5In
0.5P contact layer (thickness 0.2 μ m) 23, and the transparent electrode layer of making by zinc oxide 30.In addition, another surface (bottom surface among Fig. 6 A) that the n type electrode of being made by AuSi 32 is located at GaP substrate 29 is as first electrode, and by the bonding pad that Au makes establish 31 on the surface of transparent electrode layer 30 (end face among Fig. 6 A) as second electrode.
Shown in Fig. 6 C, each all is processed to have the relatively little roundel of 30 μ m diameters n type electrode 32, and numerous roundels (in this example, 9 roundels are arranged to 3 row, 3 row altogether) are configured to matrix form in the bottom surface.Shown in Fig. 6 B, bonding pad 31 is processed to have the big relatively roundel of 120 μ m diameters, and this roundel is set at the centre of end face.
Though do not show its details, quantum well active layer 25 has a kind of like this structure to make a plurality of by (Al
0.7Ga
0.3)
0.5In
0.5The barrier layer that P makes and by (Al
0.3Ga
0.7)
0.5In
0.5The trap layer that P makes hockets stacked.By (Al
yGa
1-y)
zIn
1-zIt is the emission light of 550nm～670nm that P (wherein 0≤y≤1,0≤z≤1) formation quantum well active layer 25 provides wavelength as luminescent layer.
Light emitting semiconductor device is made with the following step.
I) at first, as shown in Figure 7, on a surface (end face among Fig. 7), grow successively and stacked p type GaAs resilient coating (thickness 1 μ m) 22, p type (Al by MOCVD (metal organic chemical vapor deposition) method as the n type GaAs substrate 21 of first Semiconductor substrate
0.5Ga
0.5)
0.5In
0.5P contact layer (thickness 0.2 μ m) 23, p type Al
0.5In
0.5P cover layer (thickness 1 μ m) 24, p type quantum well active layer 25, n type Al
0.5In
0.5P cover layer (thickness 1 μ m) 26, n type (Al
0.2Ga
0.8)
0.77In
0.23P intermediate layer (thickness 0.15 μ m) 27, and n type GaP protective layer (thickness 1 μ m) 28.
Ii) secondly, top at above-mentioned layer, as shown in Figure 8, n type GaP layer (hereinafter being called " GaP substrate ") 29, carried out epitaxial growth to reach target thickness enough with regard to mechanical strength, just about in this example 100 μ m as second Semiconductor substrate with the VPE method.
Iii) then, as shown in Figure 9, n type GaAs substrate 21 and p type GaAs resilient coating 22 are etched based on the etchant of ammonium and hydrogen peroxide by using.
What notice is that n type GaP substrate 29 usefulness VPE methods grow to target thickness, have eliminated polishing or the like to adjust the necessity of n type GaP substrate 29 thickness in this stage like this.Therefore, compare with the situation that forms GaP substrate 29 by direct joint, this manufacturing step can obtain simplifying.
Iv) then, as shown in Figure 6A, the transparency electrode of being made by zinc oxide 30 is at p type (Al
0.5Ga
0.5)
0.5In
0.5The surface of P contact layer 23 forms, and further forms the bonding pad of being made by Au 31 in the above.At last, on the bottom surface of n type GaP substrate 29, form 9 circular n type electrodes of making by AuSi 32.
The external quantum efficiency of the light emitting semiconductor device of Zhi Zaoing is assessed under the condition that by the electric current between bonding pad 31 and the n type electrode 32 is 20mA like this, and this external quantum efficiency is 4.2%.Under identical condition, the thickness that comprises of conventional configurations is that the external quantum efficiency of light emitting semiconductor device of the p type AlGaAs current-diffusion layer of 5 μ m is about 3.0%.This result confirms that the external quantum efficiency that the light emitting semiconductor device among this embodiment has than conventional light emitting semiconductor device improves about 1.4 times external quantum efficiency.
Though p type (Al in this embodiment
0.5Ga
0.5)
0.5In
0.5P is used as contact layer, and still, those materials of being made up of littler Al mixed crystal ratio are Ga for example
0.5In
0.5If P enough little in the light absorption at radiative wavelength place, also can be used as contact layer.Under the less situation of the mixed crystal ratio of Al, the surface becomes and has oxidation resistance, and higher doping content is provided thus.In this case, the voltage drop between reduction transparent electrode layer and the p type semiconductor layer on the interface becomes possibility, reaches the increase of device efficiency thus.In addition, the same with first embodiment, GaP protective layer 28 contacts with GaP substrate 29, has prevented like this because the generation that the VF (forward voltage) that the heterojunction between GaP layer and the GaP substrate causes raises.
Though Si doped n type GaAs substrate is used as first Semiconductor substrate in the above-described embodiments, the invention is not restricted to this.The GaAs substrate that diffuse dopants enters negligible basically not doping type of luminescent layer or weak p type can bring identical effect.Diffuse into luminescent layer negligible basically " weak p type GaAs substrate " for the GaAs substrate being included into make, the p type carrier concentration in the GaAs substrate is set to, and for example 1 * 10
18Cm
-3Or littler just enough, be 5 * 10
17Cm
-3Or littler better, be 1 * 10
17Cm
-3Or littler especially suitable, although it may depend on thermal history on the horizon.Under the thermal history situation described in each embodiment, if the p type carrier concentration in the GaAs substrate is about 5 * 10
17Cm
-3Or littler, then determine to diffuse into luminescent layer for enough little.If first Semiconductor substrate is the GaAs substrate, make the high brightness semiconductor light emitters part comprise by the semiconductor layer made from the GaAs substrate lattice matched materials possibility that becomes.
Be not limited to zinc oxide, the material of transparent electrode layer can comprise indium oxide, tin oxide, indium tin oxide, and magnesium oxide.If transparent electrode layer is by indium oxide, tin oxide, indium tin oxide, zinc oxide, and magnesian at least a composition, obtain 90% or the higher visible light transmissivity possibility that becomes.Therefore, it has further guaranteed the realization of high brightness.
The present invention describes like this, and is apparent, can change in many aspects.Such variation is not regarded as a departure from the spirit and scope of the present invention, and all conspicuous to those skilled in the art these changes all comprise within the scope of the appended claims.
Claims (11)
1. a method of making light emitting semiconductor device is characterized in that, comprising: luminescent layer is layered in not doping type, weak p type, and perhaps on n type first Semiconductor substrate, this luminescent layer is made up of the single or multiple lift semiconductor layer;
The n type semiconductor layer is layered on the luminescent layer, and this n type semiconductor layer is made up of single or multiple lift;
Form second Semiconductor substrate at n N-type semiconductor N laminar surface, this second Semiconductor substrate is transparent for the light emitted wavelength of luminescent layer;
Remove first Semiconductor substrate then; And
Form transparent electrode layer on the plane that first Semiconductor substrate exposed removing, this transparent electrode layer is transparent for the light emitted wavelength of luminescent layer.
2. the method for manufacturing light emitting semiconductor device as claimed in claim 1 is characterized in that, further comprises:
Before described luminescent layer being laminated on described first Semiconductor substrate, on described first Semiconductor substrate, form the p type semiconductor layer, wherein, described p type semiconductor layer is formed the single or multiple lift that is different from first Semiconductor substrate by it and is formed.
3. the method for manufacturing light emitting semiconductor device as claimed in claim 1 is characterized in that, described second Semiconductor substrate forms by directly engaging.
4. the method for manufacturing light emitting semiconductor device as claimed in claim 1,
It is characterized in that second Semiconductor substrate forms by epitaxial growth.
5. the method for manufacturing light emitting semiconductor device as claimed in claim 2 is characterized in that, described second Semiconductor substrate forms by directly engaging.
6. the method for manufacturing light emitting semiconductor device as claimed in claim 2 is characterized in that, described second Semiconductor substrate forms by epitaxial growth.
7. the method for manufacturing light emitting semiconductor device as claimed in claim 2,
It is characterized in that the p type semiconductor layer has 1 * 10
18Cm
-3To 1 * 10
19Cm
-3Carrier density in the scope, and comprise for the transparent Al of the light emitted wavelength of luminescent layer
xGa
1-xAs layer, wherein 0.5≤x≤0.7.
8. the method for manufacturing light emitting semiconductor device as claimed in claim 2,
It is characterized in that the p type semiconductor layer has 1 * 10
18Cm
-3To 1 * 10
19Cm
-3Carrier density in the scope, and comprise for the transparent (Al of the light emitted wavelength of luminescent layer
yGa
1-y)
zIn
1-zP layer, wherein 0≤y≤1,0≤z≤1.
9. the method for manufacturing light emitting semiconductor device as claimed in claim 2,
It is characterized in that the p type semiconductor layer has 3 μ m or littler thickness.
10. a light emitting semiconductor device is characterized in that, comprising:
Stacked on a surface of GaP substrate with this sequential cascade by luminescent layer and transparent electrode layer that single or multiple lift is formed, this GaP substrate and transparent electrode layer are transparent for the light emitted wavelength of luminescent layer;
Wherein, the luminescent layer of being made up of single or multiple lift forms by directly being bonded on the GaP substrate;
On another surface of GaP substrate, provide first electrode; And
Provide second electrode so that be connected to transparent electrode layer.
11. light emitting semiconductor device as claimed in claim 10 is characterized in that, further comprises the GaP layer between the luminescent layer that is arranged on the GaP substrate and is made up of single or multiple lift, this GaP layer contacts with the GaP substrate.
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| JP5227613B2 (en) * | 2008-02-27 | 2013-07-03 | スタンレー電気株式会社 | Semiconductor light emitting device |
| CN103199437B (en) * | 2009-07-06 | 2015-07-22 | 古河电气工业株式会社 | Method for manufacturing semiconductor optical device, method for manufacturing semiconductor optical laser element, and semiconductor optical device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5571321A (en) * | 1993-11-22 | 1996-11-05 | Shin-Etsu Handotai Co., Ltd. | Method for producing a gallium phosphide epitaxial wafer |
| JP2000196139A (en) * | 1998-12-25 | 2000-07-14 | Sharp Corp | Fabrication of semiconductor light emitting element |
| US6265732B1 (en) * | 1998-11-30 | 2001-07-24 | Sharp Kabushiki Kaisha | Light emitting diode |
-
2003
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5571321A (en) * | 1993-11-22 | 1996-11-05 | Shin-Etsu Handotai Co., Ltd. | Method for producing a gallium phosphide epitaxial wafer |
| US6265732B1 (en) * | 1998-11-30 | 2001-07-24 | Sharp Kabushiki Kaisha | Light emitting diode |
| JP2000196139A (en) * | 1998-12-25 | 2000-07-14 | Sharp Corp | Fabrication of semiconductor light emitting element |
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