CN101506937A

CN101506937A - Optical devices featuring textured semiconductor layers

Info

Publication number: CN101506937A
Application number: CNA2006800496104A
Authority: CN
Inventors: T·D·穆斯塔克斯; J·S·卡布鲁
Original assignee: BOSCHTON UNIV BOARDOF DIRECTORS
Current assignee: BOSCHTON UNIV BOARDOF DIRECTORS
Priority date: 2005-10-31
Filing date: 2006-10-31
Publication date: 2009-08-12
Also published as: CA2627880A1; JP2009515340A; WO2007053624A2; WO2007053624A3; EP1952449A4; EP1952449A2

Abstract

A semiconductor sensor, solar cell or emitter, or a precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate. The textured layers enhance light extraction or absorption. Texturing in the region of multiple quantum wells greatly enhances internal quantum efficiency if the semiconductor is polar and the quantum wells are grown along the polar direction. Electroluminescence of LEDs of the invention is dichromatic, and results in variable color LEDs, including white LEDs, without the use of phosphor.

Description

Be characterized as the optics of textured semiconductor layers

The cross reference of related application

This application requires the name of on October 31st, 2005 application to be called the priority of No. 60/732034, the U.S. Provisional Application of " OPTICAL DEVICESFEATURING TEXTURED SEMMICONDUCTOR LAYERS ". the part that this application or the name of on April 15th, 2005 application are called No. 11/107150, the U. S. application co-pending of " OPTICAL DEVICES FEATURING TEXTURED SEMMICONDUCTORLAYERS " continues; Should after an application require the priority of following patent: the name of application on April 15th, 2004 is called No. 60/562489, the U.S. Provisional Application of " FORMATION OFTEXTURED III-NITRIDE TEMPLATES FOR THE FABRICATION OFEFFICIENT OPTICAL DEVICES "; The name of on October 1st, 2004 application is called No. 60/615047, the U.S. Provisional Application of " FORMATION OF TEXTURED III-NITRIDETEMPLATES FOR THE FABRICATION OF EFFICIENT OPTICALDEVICES ", and the name of application on January 21st, 2005 is called No. 60/645704, the U.S. Provisional Application of " NITRIDE LEDS BASED ON FLAT AND WRINKLED QUANTUMWELLS ". In addition, this application is that PCT/US/2005/012849 number the part that the name of on April 15th, 2005 application is called " OPTICAL DEVICES FEATURING TEXTUREDSEMMICONDUCTOR LAYERS " continues.Incorporated each application early listed above by reference in this.

About the research of federal government's subsidy or the statement of exploitation

The part work that causes this invention is to utilize contract DAAD19-00-2-0004 number of being authorized by Unite States Army Research Office and finish from the American National government-funded that provides under appropriation DE-FC26-04NT42275 number of United States Department of Energy.Therefore U.S. government has some right in this invention.

Background technology

Light-emitting diode (LED) is the optics that can produce light in infrared, visible or ultraviolet (UV) district.Make at the LED use gallium nitride (GaN) of visual field and ultra-violet (UV) band emission with its alloy of indium nitride (InN) and aluminium nitride (AlN).These devices generally include p and the n type semiconductor layer that is arranged in the p-n junction.In standard LED device, semiconductor layer grow into equably polishing such as in GaAs or the sapphire substrate.Typical semiconductor layer comprises gallium nitride (GaN), and it has been doped to p or n type layer.

Important numeral at the quality of LED is its internal quantum efficiency (IQE) and light extraction efficiency.For typical LED, IQE depends on many factors, such as the concentration of point defect, and Auger process and designs.The utmost point is under the situation of the nitride LED of growth on edge (0001) with (000-1), and owing to the n that is caused by internal electric field and the distortion of the quantum well between the p doped layer, internal efficiency has also reduced.Light extraction efficiency based on the standard LED of GaN is defined as every surperficial 4% by the Snell law.LED generally includes several by the little quantum well of can gap semiconductor (trap) and making than wide band gap semiconducter (base).As seen LED use indium gallium nitrogen (InGaN) as trap and GaN as the base.Ultraviolet LED uses the AlGaN of different component as trap and base.Based on reducing to the electric field that the IQE of the LED device of the nitride-based semiconductor of growth is striden across its quantum well along the utmost point.This phenomenon is called quantum limit Stark effect (QCSE).By the red shift emission wavelength with reduce photoluminescence intensity, QCSE influence LED light and launches.Quite little light extraction efficiency value is to export the result of the high refractive index of semiconductor layer at the interface among the standard LED.

Having proposed a plurality of approach strengthens the extraction from the light of LED.For example, in GaAsLED, the extraction of light is subjected to the influence of the absorption of the light launched in the GaAs substrate.In order to alleviate this problem, can use extension to peel off and shift GaAs LED structure on transparent substrates with method of wafer bonding.Another comprises LED surface geometry (such as the reverse pyramid of tack) and optimizes, will extract to limit with the approach of the use combination of substrate speculum and raise 30%.Other approach comprises and uses the transparent material of variable refractive index continuously to reduce back reflection at the interface.Some of these approach have some manufacturing restrictions and last is subjected to the influence of coefficient-material degeneration fast in time.

The attractive day by day approach that becomes recently is that the film surface from little texture irregularly extracts photon.It has significantly the extraction efficiency of improving, and has write down 44% the external quantum efficiency (Windish etc., 2000) that GaAS base LED is showed in room temperature.In this reference, after using lithographic process growth LED, form the surface of texture.The result shows, even under the sort of situation, has still extracted most of photons in boring corresponding to the emission inside the critical angle on flat surface.Therefore, still exist wide space to extract far above currency to improve.

Based on the visible and UV LED of GaN and other III-nitride material be widely used in that full-color display, automotive lighting, consumer electronics are backlight, traffic lights and the White LED that is used for solid-state illumination.A plurality of approach are used to form White LED.An approach is to utilize three-color LED (RGB), and optional approach is to use the mixed method such as the combination of UV LED and tri-color phosphor or blue and blue/red LED and two kinds or a kind of fluorophor.Current White LED performance has reached 30lm/W, and for the semiconductor lighting of commercially attractive, the efficient that needs is higher than 200lm/W.

The current I QE that is converted to photon for the electron-hole pair of nitride LED is～21% (Tsao, 2002).Therefore, for the application that relates to solid-state illumination, IQE need bring up to 60%-70%.In order to realize this, need be to a plurality of improvement of this area current state.For example, must comprise band gap engineering (quantum well, quantum dot) with optimization charge carrier-photon conversion.Also have, thereby need improve a plurality of layers in the LED structure to reduce defect concentration and to be improved to the transportation of the charge carrier of active area.This improvement reduced parasitic heating and cause the color stability of the long-life of device, enhancing and the whole term of validity in consumer's cost of reducing.

Summary of the invention

The invention provides a kind of device, to be used as optical transmitting set or transducer or solar cell.For based on reflector of the present invention,, IQE and light extraction efficiency have been improved with respect to traditional devices such as the polar semiconductor of III-nitride.For transducer or solar cell, the efficient that couples light in the device has also been improved.In one embodiment, the stratified sedimentation semi-conducting material, the initial semiconductor layer that deposits to suprabasil texture during with growth begins.In one embodiment, layer when growth irregularly texture in substrate, make configuration of surface with texture.Substrate and texture the layer can with act on the growth a plurality of semiconductor layers model.For example, device can comprise the second layer on the layer that is deposited on first texture.Can utilize these layers of p and n dopant deposit, to form p-n joint LED.The emission layer of texture strengthens light and escapes.Initial semiconductor layer preferably is used as the base layer of grown quantum trap layer thereon.Each semiconductor layer defer to the texture of first grown layer and therefore light have and the initial approximately uniform texture of semiconductor layer from the outer surface of the LED of its extraction.

Preferably, it is over each other to comprise that a plurality of Multiple Quantum Well of building layer and quantum well layer are deposited on as the semiconductor layer that replaces, every layer of replicating original texture.By building and the position of the texture change quantum well that the trap layer duplicates, the utmost point that makes that their surface is not orthogonal to [0001] to.Thereby quantum well keeps almost their square trap shape, because they are not by the internal field distortion owing to polarization.Hole and electron wave function overlap as a result, thereby cause effectively compound and greatly improved IQE.

Device of the present invention can comprise substrate, such as silicon (Si), GaAs (GaAs), gallium nitride (GaN), aluminium nitride (AlN), indium nitride (InN), aluminum gallium nitride (AlGaN), indium gallium nitrogen, indium aluminium nitrogen, indium-gallium-aluminum-nitrogen (InAlGaN), carborundum, zinc oxide, sapphire, and glass.Can also before sedimentary deposit on the sapphire substrates, carry out nitrogenize to it.

Can in whole growth technology, be grown in semiconductor layer on GaN model or other layer by any suitable process deposits.The example of this depositing operation comprises hydride gas-phase epitaxy (HVPE), molecular beam epitaxy (MBE), metal-organic chemical vapor deposition equipment (MOCVD), liquid phase epitaxy and laser ablation.Semiconductor device layer can comprise any combination such as III-nitride or these materials of GaN, AlN, InN.Can be before layer growth or by selecting suitable growing condition come textured substrate, make the surface that has texture at suprabasil first semiconductor layer.

Semiconductor layer can comprise dopant, makes that layer is p or n type.The example dopant comprises the combination of beryllium, selenium, germanium, magnesium, zinc, calcium, Si, sulphur, oxygen or these dopants.Layer also can be list or polycrystal layer.Device of the present invention can also comprise several p and n type layer and one or more resilient coating, and resilient coating helps layer growth usually.The example resilient coating is the GaN semiconductor layer.Resilient coating can deposit in the substrate or between semiconductor layer.

Be used for device of the present invention semiconductor layer deposit thickness can from about 10 dusts to (

) 100 microns (μ m).The texture of the layer of GaN model and deposition has the average peak-paddy distance of about 100 nanometers (nm) to 5 μ m.

The present invention also provides the method for making semiconductor device of the present invention.This method comprises provides substrate and growth regulation semi-conductor layer on the surface of substrate.Ground floor can be in when growth texture or the substrate surface by texture texture irregularly spontaneously irregularly.Substrate or ground floor can be used as model has the texture identical with model with deposition other semiconductor layer then.In a preferred embodiment, manufacture method comprises several quantum well of growth.Make up the texture Multiple Quantum Well by ground floor, substrate or its.

Description of drawings

Other features and advantages of the present invention will become obvious from the detailed description of the present invention below in conjunction with accompanying drawing.

Fig. 1 is that the part of the model of texture of the present invention is described;

Fig. 2 a and 2b are deposited on the model of texture of Fig. 1 with the part of the semiconductor layer that forms p-n junction to describe;

Fig. 3 a and 3b are deposited on Multiple Quantum Well on the model of texture of Fig. 1 and the part of semiconductor layer is described;

Fig. 4 a and 4b are that the part of substrate with surface of texture is described, and this surface texture comprises the semiconductor layer of the Multiple Quantum Well of deposition on it;

Fig. 5 a and 5b are that the part of substrate with surface of texture is described, and deposit the textured semiconductor layers that comprises Multiple Quantum Well on the surface of texture; Fig. 5 c is based on the diagram of the UV LED structure of nitride-based semiconductor;

Fig. 6 is transmission electron microscope (TEM) view that is grown in the GaN/AlGaN Multiple Quantum Well of the texture on the GaN model of texture;

Fig. 7 is the GaN wafer scale LED with radiation electric pumping of InGaN MQW;

Fig. 8 a is scanning electron microscopy (SEM) image of the model of gallium nitride of the present invention (GaN) texture;

Fig. 8 b is the SEM image of traditional, level and smooth GaN semiconductor layer;

Fig. 8 c shows the configuration of surface of the level and smooth GaN model of Fig. 8 b by AFM;

Fig. 9 is the contrast of the luminescence generated by light between the model of texture of traditional GaN layer and Fig. 8 a;

Figure 10 a is atomic force microscope (AFM) image of model of the texture of Fig. 8 a; Figure 10 b shows the depth analysis figure in the zone of imaging;

Figure 11 and 12 shows traditional, level and smooth quantum well (Figure 11) and is grown in the photoluminescence spectrum of the quantum well (Figure 12) of the texture on the model of texture of Fig. 8 a;

Figure 13 is the electroluminescence spectrum of p-n junction LED device of model that comprises the texture of Fig. 8 a;

Figure 14 a shows commercial available White LED (Lumileds LXHL-BW02; The single DS25 of technical data) emission spectrum; Figure 14 b shows the electroluminescence spectrum (being grown in the InGaN/GaN of the texture on the GaN model of the texture of being produced by HVPE) of LED of the present invention, records under the DC of 30mA injection current; The radiation white GaN LED of DC injection current figure below 14b that Figure 14 c shows at 25mA;

Figure 15 a-15c shows the electroluminescence spectrum with the similar LED of LED of the data that are used to obtain Figure 14 b, uses the value of the indication of DC injection current;

Figure 16 is the photo of the LED under the condition of describing among Figure 15 b, shows most of wafer transmitting green lights, and some part emission blue light;

Figure 17 shows the electroluminescence spectrum of the LED structure that obtains from the part of the wafer with different texture; The DC injection current is listed in the right side of each curve chart with the order identical with corresponding curve;

Figure 18 is atomic force microscope (AFM) image by the level and smooth GaN model of the atom level of 50 micron thickness of HVPE growth; Visual striation is corresponding to about 2

The step of varied in thickness;

Figure 19 is the schematic diagram of the cross section of certain LED embodiment;

Figure 20 is the schematic diagram of hvpe reactor device;

Figure 21 is the reflectance spectrum via the GaN model of the irregularly texture of HVPE growth;

Figure 22 a shows the photoluminescence efficiency of several GaN models on the surface with level and smooth and texture in various degree; Figure 22 b show have level and smooth or texture the surface and have the photoluminescence efficiency of two GaN models of identical carrier concentration;

Figure 23 shows the surperficial texture that obtains in the GaN film be grown in sapphire R plane (1-102) by HVPE on;

Figure 24 shows the reflectivity on the surface of the texture of describing among Figure 23;

Figure 25 a shows the configuration of surface of the GaN model (VH81) of the texture that obtains by AFM; Figure 25 b is the roughness analysis of the model of the texture among Figure 25 a;

Figure 26 a shows the depth analysis of the model of the texture among Figure 25 a; Figure 26 b shows the spectrum density analysis of the model of the texture among Figure 25 a;

Figure 27 a shows the configuration of surface of the GaN model (VH129) of the texture that obtains by AFM; Figure 27 b is the roughness analysis of the model of the texture among Figure 27 a;

Figure 28 a shows the depth analysis of the model of the texture among Figure 27 a; Figure 28 b shows the spectrum density analysis of the model of the texture among Figure 27 a;

Figure 29 a shows the configuration of surface of the GaN model (VH63) of the texture that obtains by AFM; Figure 29 b is the roughness analysis of the model of the texture among Figure 29 a;

Figure 30 a shows the depth analysis of the model of the texture among Figure 29 a; Figure 30 b shows the spectrum density analysis of the model of the texture among Figure 29 a;

Figure 31 a shows the configuration of surface of the GaN model (VH119) of the texture that obtains by AFM; Figure 31 b is the roughness analysis of the model of the texture among Figure 31 a;

Figure 32 a shows the depth analysis of the model of the texture among Figure 32 a; Figure 32 b shows the spectrum density analysis of the model of the texture among Figure 31 a;

Figure 33 a, 33b, 33c, and 33d show at having respectively as Figure 25 a, 27a, 29a, reaching the photoluminescence spectrum of the GaN model of the different r.m.s. roughness of describing among the 31a;

Figure 34 show at Figure 25 a, 27a, 29a, and 31a in the peak density of model of texture and the relation curve of r.m.s. roughness;

Figure 35 shows AFM configuration of surface and the roughness analysis of the GaN/AlGaN MQW on the model (VH129) that is grown in GaN texture;

Figure 36 shows at the grow photoluminescence spectrum of model (VH129 is with reference to Figure 28) of GaN texture of MQW structure of GaN (7nm) Al0.2Ga0.8N (8nm) MQW structure and being used to;

Figure 37 show texture with level and smooth atomically GaN model on the photoluminescence spectrum of identical GaN/AlGaN MQW by the MBE growth;

Figure 38 schematically shows the type of the surface location of the cathodoluminescence analysis that is used for shown in Figure 39;

Figure 39 shows the cathodoluminescence spectrum that some A to the C place that indicates obtains in Figure 38;

Figure 40 a shows the effect of quantum well distortion; Figure 40 b shows along non-to (M plane) and the utmost point photoluminescence peak position to the AlGaN/GaN MQW of (C plane) growth;

Figure 41 a shows the AFM scanning on the model surface of texture; Figure 41 b shows the depth analysis from the AFM data of Figure 41 a;

Figure 42 shows the figure at the relation curve of the electron mobility of the GaN model of texture and electron concentration;

(Figure 43 a) and the analysis of the photon escape possibility on (Figure 43 b) of texture surface at level and smooth for Figure 43 a and 43b example;

Figure 44 shows near the x ray diffraction pattern (0002) Bragg peak value of ten cycle GaN (7nm) on the model that is grown in GaN texture/Al0.2Ga0.8N (8nm) MQW;

Figure 45 a and 45b are by level and smooth (45a) of MBE preparation and (45b) GaN model of random texture; The random surperficial texture of Figure 45 b produces by GaN film grown under rich nitrogen condition;

Figure 46 a and 46b show at the luminescence generated by light emission peak (46a) of the quantum well layer of different-thickness and luminous intensity (46b);

Figure 47 a shows polarization and the internal electric field effect in the quantum well layer of tool wrinkle; Figure 47 b shows the electron accumulation in the bottom of the sloping portion of the quantum well layer of tool wrinkle;

Figure 48 is the diagram of variable color indicating device embodiment;

Figure 49 is the diagram of variable color illuminating device embodiment;

Figure 50 is the diagram of color monitor embodiment; And

Figure 51 is the diagram of color projecting apparatus embodiment.

Embodiment

All be improved aspect the one side or two of LED of the present invention or photodetector extraction efficiency and IQE outside light.Utilize the emitting surface of texture to improve light extraction efficiency, typically pass through from the emitting surface of the technology reflex weaving structure of initial semiconductor base layer applied layer.In addition, LED of the present invention has two look electroluminescence spectrums, and its color is by the bias current control by LED.

Control growing speed also uses suitable deposition program will form the superficial layer of texture in initial substrate.Apply when layer subsequently, the layer by subsequently duplicates this texture, the emission layer of the light extraction efficiency that has been greatly enhanced.Substrate that can also be below texture respectively or use to decorate and have the unpolished substrate of dark groove to reach final surperficial texture, dark groove is because wafer uses saw to cut from blank usually.

Raising among the IQE of LED was reached by incorporating into of the Multiple Quantum Well in the p-n junction (MQW).Thereby this causes respectively from the restriction preferably in n and p side injected electrons and hole and more effective compound.

When the semiconductor device that comprises quantum well was grown in the utmost point and makes progress, the quantum well that obtains was twisted, but cause the hole electronics separately.This with electronics-void area place away from, reduced to be used for the efficient of the hole-electron recombination of photogenerated.By grown quantum trap on the surface of texture, LED of the present invention has overcome this defective.Like this, quantum well is distortion not, thereby and the electronics in the trap and hole more effectively compound.

In an embodiment according to LED of the present invention, LED is formed in the substrate 2, and textured semiconductor layers 4 is deposited in the substrate as shown in Fig. 1 and Fig. 2 a and 2b, discusses more fully below.In substrate during grown layer with layer texture, make surface topology (or form) 10 with texture.The layer of substrate and texture can be used to form the model of growth of a plurality of semiconductor layers of LED.The AlN model of this texture also can be used to produce UV LED.For example, device can comprise the second layer on the layer that is deposited on first texture.These layers can be doped to be formed for the p-n junction of LED.Suitable dopant can comprise selenium, germanium, zinc, magnesium, beryllium, calcium, Si, sulphur, oxygen or its any combination.By copying surface from first grown layer and its texture, can each semiconductor layer of texture, obtain having the emitting surface of texture of the extraction efficiency of raising.

In another embodiment, as Fig. 3 a, b, Fig. 4 a, b, and shown in Fig. 5 a, the b, discuss more fully below, the Multiple Quantum Well that comprises a plurality of bases and quantum well layer is deposited on each other as the n of device and the alternately semiconductor layer between the p doped layer and goes up.As used in this, term " quantum well " refers to quantum well layer and adjacent base layer together.By the copying surface from the texture of ground floor during Multiple Quantum Well of growth on ground floor, with Multiple Quantum Well texture.

As a rule, the AlGaN covering of the n of variable thickness doping is grown between the layer and quantum well layer of texture.

The suitable substrate that can be used in the growth of ground floor is known in this area.The example substrate comprises sapphire, GaAs (GaAs), gallium nitride (GaN), aluminium nitride (AlN), carborundum, zinc oxide silicon (Si) and glass.For example, preferred substrate can comprise (0001) zinc oxide, (111) Si, (111) GaAs, (0001) GaN, (0001) AlN.(0001) sapphire, (11-20) sapphire and (0001) carborundum.

Can prepare the substrate that is used for device of the present invention by chemically cleaning growing surface, be used for semiconductor growth layer.Alternatively, can polish the growing surface of substrate.Before layer growth, can also carry out hot degasification to substrate.Substrate surface can be exposed to nitrogenize alternatively, such as disclosed in No. 6953703, the United States Patent (USP), by reference it is incorporated in this.On the suprabasil growth of unpolished, unprocessed, the cutting like this surface of growth texture thereon.

Semiconductor layer can be by the technology growth such as the distortion of hydride gas-phase epitaxy (HVPE) (its alternative name is the halide vapour phase epitaxy), MOCVD or MBE, liquid phase epitaxy (LPE), laser ablation and these methods.In United States Patent (USP) No. 5725674, No. 6123768, No. 5847397 and No. 5385862, disclose typical growth technique, by reference they have been incorporated in this.Can also exist under the situation of nitrogen grown semiconductor layer to produce nitride layer.The example of nitride layer is GaN, InN, AlN and their alloy.

Fig. 1 shows the part of semiconductor device of the present invention and describes.In a preferred embodiment, device by texture and comprise substrate 2 and when growing thereon by the ground floor 4 of texture.Substrate 2 can be initially level and smooth by texture or polishing.When growing, ground floor 4, has the surface topology 10 of texture by texture in substrate 2.Preferably, the HVPE depositing operation growth regulation one deck by change is to produce the surface 10 of texture.The HVPE process portion of change comes the defect area of etch layer to produce texture when growth regulation one deck by hydrochloric acid (HCl) concentration of utilizing increase.The HCl concentration of the HVPE technology of change is basically such as the concentration height of the HCl of following illustrational typical depositing operation.

In one embodiment, ground floor 4 can be the semiconductor layer that comprises the III group iii nitride layer.Layer 4 is p or the n type semiconductor layer by suitable doping formation in when deposition preferably, perhaps its can be as the insulating barrier of for example AlN or the both be, as follows.Layer 4 can be grown in alternatively and is deposited on the suprabasil resilient coating, such as what describe in No. 5686738, United States Patent (USP), by reference it is incorporated in this.

The thickness of substrate 2 and layer 4 can be contained wide scope, though the thickness of layer 4 can influence the degree of the texture of duplicating in its surface.For example, the layer that 100 μ m are thick can have peak-paddy texture distance of about 100nm to 5 μ m.The grow light extraction efficiency of semiconductor layer of the LED layer that duplicates this texture on it of the texture influence of semiconductor layer.Typically at when growth texture semiconductor layer 4 irregularly.Layer 4 can be monocrystalline or polycrystalline material.

Fig. 2 a shows the second layer 8 on the device that is grown in Fig. 1.Layer 8 can be by any suitable depositing operation growth.The second layer is grown on the surface of texture of ground floor 4.The second layer 8 does not preferably have thick in the surface topology 10 of burying the texture of ground floor 4 as shown in Fig. 2 b.Preferably, the second layer 8 can have upper surface 9, by duplicating this surface texture according to layer 4 as shown in Fig. 2 a.

Preferably, layer 8 is the semiconductor layers that comprise the III group-III nitride.P that the second layer 8 is opposite with the doping of layer 4 typically or n type semiconductor layer.The second layer 8 can be monocrystalline or polycrystal semiconductor layer.In one embodiment, first and

second layer

4 and 8 formation p-n junction 3 that mixes is as optical sensor or reflector.These devices can be used in electronic console, solid state lamp, computer or solar panel,

electrode

11 and 13 is connected to

layer

4 and 8, use for this, and it is known in this area.

Fig. 3 a and 3b are that the part with LED of the Multiple Quantum Well 6 on the device that is grown in Fig. 1 is described.Surface topology texture quantum well 6 by ground floor 4.As above-mentioned, texture ground floor 4 in the time of can be on growing into substrate 2.In one embodiment, Multiple Quantum Well 6 can comprise one or more quantum well layers 7 of building layer 5 and replacing.

Several build layer 5 and quantum well layer 7 can be as the semiconductor growth layer that replaces, every layer of ground floor 4 that duplicates texture.For example, can form quantum well by the base layer 5 that is grown on the ground floor 2.Quantum well layer 7 can grow into then to be built on the layer 5.Second builds layer 5 is grown on the quantum well layer 7 second quantum well layer of then growing then.In one embodiment, the component of quantum well layer 7 and ground floor 4 is components do match.The component of building layer 5 can be different from ground floor 4 and quantum well layer 7.

Build layer 5 and can comprise one or more III-V group-III nitride compounds.In one embodiment, one or more base layer 5 is AlGaN.Similarly, one or more quantum well layers 7 are III group-III nitrides, such as GaN, or other III-V compound.Also can pass through any suitable depositing operation grown layer.Layer can be single crystalline layer or polycrystal layer.

For the texture of following layer, every layer thickness is typically enough thin, can copy to top surface.Degree to layer texture can influence IQE and light extraction efficiency.Preferably, device of the present invention comprises from one to 20 quantum well, and it comprises a plurality of bases layer 5 and quantum well layer 7.

Fig. 3 a and 3b also show on the quantum well 6 that is grown in multiple texture than upper semiconductor layer 8.Layer 8 can and can be that (Fig. 3 a) or thick feasiblely bury the surface topology (Fig. 3 b) of the texture of ground floor 4 or it is wiped (polish off) for the layer 9 of texture by the growth of known depositing operation.

Preferably, layer 8 is the semiconductor layers that comprise the III group-III nitride.Can also be p or n type semiconductor layer than upper strata 8, opposite with layer 4, so that form p-n junction.P-n junction is allowed as the semiconductor device such as LED or photo-detector.Than upper strata 8 can be monocrystalline or polycrystal semiconductor layer.The base layer 5 and the quantum well layer 7 of texture when Multiple Quantum Well 6 also can comprise growth.For example,

layer

5 and 7 can be by the depositing operation growth such as HVPE, MBE or MOCVD.

Device architecture shown in Fig. 3 a can show the internal quantum efficiency and the outer light extraction efficiency of the efficient that is significantly higher than traditional devices.The device of Fig. 3 b has overall IQE and increases.

Device of the present invention can have the light extraction efficiency near a hundred per cent (100).Similarly, the IQE of this device can be in 50 to 60 percent scope or higher.

Fig. 4 a and 4b show substrate and have the device on the surface of texture initially.Can be deposited in the substrate 2 of texture from the layer subsequently of ground floor 4, make than the upper surface quilt by duplicating texture.

The device of Fig. 4 a is included in the surface 9 of the texture of layer on 8, or the layer of the not texture among this embodiment among Fig. 4 b.

In optional embodiment, the

surface

9 and 15 of that substrate can comprise and texture down, as for example in use among Fig. 5 a shown in above-mentioned essentially identical program.In Fig. 5 b, only the surface 15 of bottom 2 be texture and can be used as emitting surface.

For example, Fig. 5 c is the LED that uses level and smooth AlN model 4a on sapphire substrates 2.Between AlN model and quantum well and

base layer

7 and 5, there be the thick AlGaN layer 4b that is called covering or contact layer.This layer can use with other form of the present invention in this description.On those

layer

8a and 8b that is respectively the p doping of AlGaN and

GaN.Layer

4b and 8b receive and are electrically connected 11 and 13, and light extraction passes through sapphire substrates downwards.Layer 8a can be with use and be used as the electronic barrier layer that prevents loss of electrons in other form of the present invention of this description.Though

layer

5 and 7 is shown level and smooth for clear, should be appreciated that they should wrinkling for tool as expectation.

The present invention also is provided for making the method for semiconductor device of the present invention.This method comprises provides substrate and growth regulation semi-conductor layer on the surface of substrate.Ground floor can be in when growth irregularly texture, growth back slabstone printing ground texture or the texture irregularly of the substrate surface by texture as described below.Substrate or ground floor then can be as model with deposition and other semiconductor layers of texture.This model can be sold in this stage of producing, and allowed that other people finish layering and duplicate texture to emission layer.

In a preferred embodiment, manufacture method comprises several quantum well of growth, and wherein, trap comprises can be as the base and the quantum well layer of the semiconductor layer deposition that replaces.Multiple Quantum Well is by ground floor, substrate or its combination texture.

A kind of method that forms thick GaN He other III-nitride film (model) with specific texture in substrate is described in this invention.The nitride model usefulness of the texture of this spontaneous formation acts on the substrate such as the growth of the efficient device of III-nitride light emitting diode (LED), solar cell and photodetector.This device efficiently owing to two kinds of effects: (a) for LED for effective light extraction for the situation of solar cell and photodetector be in the material effective optical coupling and (b) owing to the inhibition of polarity effect based on the raising among the IQE of the LED of the III-nitride MQW of texture.

This invention relates to the method for preparing the III group-III nitride model of texture by HVPE, MOCVD and MBE growing nitride film the time.In addition, the nitride model of this texture is with the growth of the LED structure that acts on IQE with raising and more effective extraction efficiency and the substrate of manufacturing.Except that LED, be manufactured on and also will have the efficient of raising such as other device of solar cell and photodetector on this texture model.Reference is by reference in this public own United States Patent (USP) of incorporating into: 5385862,5633192,5686738,6123768,5725674.

Though the internal efficiency of LED is intrinsic material and designs character, the outer efficient of this device is the tolerance from semi-conductive light extraction efficiency.GaN refractive index and the big difference that centers between the material (being generally air) cause total internal reflection to the most of light that produce in the active material the inside.For the refractive index (n=2.5) of GaN, the escape cone of interior lights is limited in the critical angle of sin θ=1/n or θ=23.5 ° by the Snell law.The radiation of the total extraction of that restriction is in solid angle:

Ω＝2π(1—cosθ)

Thereby can calculate total mark of the light that can escape from semiconductor by remove previous expression formula with 4 π:

Ω/4π＝1/2(1—cosθ)

According to this expression formula, in GaN base LED, only extract 4% incident radiation.Thereby in LED, great majority internally radiation reflected are heavily absorbed, because among the LED below operating in lasing threshold, that passes through excites gain less than the absorption loss of passing through at every turn at every turn.

Can develop and form III-nitride model and the epitaxial growth nitride device on this model, for example, use three different epitaxy methods, below will describe them.

The HVPE method is used to develop GaN or the accurate substrate of AlN (model).This deposition process uses HCl to arrive substrate with the form transportation Ga of GaCl.The growth of GaN when having HCl also has a plurality of attendant advantages.HCl is from the unnecessary Ga of the surface etch of growing film, and this makes it possible to realize high growth rates (100-200～μ/hr).It is the defective GaN of etching also, and it mainly occurs in the boundary of hexagon farmland (hexagonal domain), not exclusively coalescent owing to this farmland (domain).At last, another advantage is the filtering of metal impurities, and it often contributes the complex centre in most of semiconductors.Thereby the method causes very high quality GaN films.

HVPE technology by change is grown according to the GaN model of texture of the present invention.The GaN model can be via the hvpe reactor device growth of change.In reactor, III family precursor can be a GaCl gas, its by contain from the quartz boat of the Ga of about 500 ℃ to the 1000 ℃ temperature HCl that flows synthetic in the upstream.GaCl gas then in the downstream at base wafer near surface and ammonia (NH ₃) mix with the formation of the temperature between about 900 ℃ to 1200 ℃ GaN.GaN of the present invention or AlN or AlGaN model can along the utmost point to or the non-utmost point to growth.Such as for example substrate with cubic symmetry of (100) Si, (001) GaAs, model can also be with their cubic structure growth by selection.In the case, growth nitride layer subsequently thereon will also have cubic symmetry.

The reactor of change is divided into four districts usually, and wherein the temperature in each district can be controlled individually.Reactor also has three transfer tubes that separate and is used for reactant gas and diluent.Nitrogen or hydrogen are as diluent and the vector gas of NH3 and HCl.Nitrogen is carried by intermediate conduit, wherein it as the gas downstream sheath to prevent the premixed of GaCl and NH3 before gas contact substrate surface.The texture of GaN layer can ascribe the etching effect of HCl to.For example, as HCl during from the surface etch Ga of grown layer, texture takes place.HCl also is etched in the defective GaN on the farmland, edge of ground floor.The HCl concentration of the HVPE technology of change is basically than the HCl concentration height of the typical sedimentary technology of avoiding texture.

Can be at the GaN model of growth texture under the high growth rates condition of the scope of about 30 to 200 μ m per hour, this growth rate is by the flow rate ratio control of NH3 and III family precursor.Flow rate ratio typically is about 300 to 10.By ammonia (nitrogenize) reaches the short time, then the thin GaN resilient coating of growth is carried out the growth of model from 550 ℃ to 650 ℃ with the preliminary treatment substrate of GaCl gas or by 1000 ℃ temperature sapphire surface being exposed to.Growth district can be risen to about 1070 ℃ of high temperature epitaxy growths that are used for GaN by oblique line then.Can also before growth, utilize the zinc oxide preliminary treatment substrate of sputter.The common thickness of zinc oxide is from about 500

To 1500

Carry out the growth of model by heated chamber to begin to grow to growth temperature and flowing reactive thing gas then.

MOCVD is the method for the growth that is used for GaN base LED of industrial current use.The method is by the reaction generation nitride of III family alkyl (for example (CH3) 3Ga or (C2H5) 3Ga) with NH3.A problem of the method is the cost relevant with the consumption of high NH3.NH3 with 1 μ/hr GaN film grown needs 5 to 10lpm.

The MBE method forms the III-nitride by the reaction of III family element and the dinitrogen that is activated by the various ways of RF or microwave plasma.Optionally approach is the suprabasil reaction that III family element and ammonia are heating.III family element can provide from effusion cell (effusion cell) evaporation or with the form of III family alkyl.It has been generally acknowledged that because the output problem, the product of producing by the MBE method is more expensive.Yet in the growth of nitride, the signal portion of cost is by the consumption decision of nitrogen precursor.When the MBE of nitride device growth, people use approximate 1 to 50sccm nitrogen or ammonia, and this is than an amplitude decimal magnitude of using when MOCVD grows.This uses the fact of polycrystalline sheet depositing system to make the MBE method attractive to the exploitation of not expensive nitride device with the MBE production equipment.Produced the laser diode [Hooper etc., Electronics Letters, Vol.40,8 Jan.2004] of InGaN base recently by the MBE method.

In one aspect of the invention, the surface of GaN model is by texture irregularly.Can produce suitable random surperficial texture by any suitable machinery or chemical technology (HVPE that comprises change).In the HVPE of change, can control the surperficial texture of GaN model by the ratio that changes III family and V family.For example, use the NH of 5:1 to 10:1 ₃Produce the irregularly GaN model of texture with the mol ratio of HCl by the HVPE that changes, and traditional HVPE uses such as 20:1 to 50:1 or the higher level and smooth model of more height ratio production.Other method of the GaN model of texture irregularly of producing comprises the incomplete nitrogenize such as the substrate of sapphire wafer, or uses GaN buffering as thin as a wafer.By the MBE method, under rich nitrogen condition, also can produce the irregularly GaN model of texture at high growth temperature GaN.For example, use molar ratio to produce the irregularly GaN model of texture less than 1 Ga/N.The molar ratio that use to surpass 1 Ga/N obtains level and smooth GaN model.

Can use such as the available technology of atomic force microscope (AFM) and scanning electron microscopy (SEM) and study surperficial texture.Distribution by the evaluation and test case depth can be determined random degree; Irregularly the surface of texture demonstrates the approximate Gaussian Profile of case depth.In order to obtain from the light extraction of the best of reflector, the average surface degree of depth is preferably in the wavelength of light emitted scope.For example, for visible light LED, the average surface degree of depth in the scope of 200nm to 1.5 μ m is preferred.

Can along the utmost point to or the non-utmost point to the III-nitride model that forms texture.

The group of reporting in the document about the work of III-nitride will partly comprise by multiple deposition process these materials of heteroepitaxial growth in (0001) sapphire or 6H-SiC substrate.Material of growing in these substrates and device comprise highdensity line defect (dislocation and counter-rotating border, farmland).In addition, [0001] orientation be in the non-centrosymmetrical wurtzite structure the utmost point to because spontaneous and polarization piezoelectricity, it causes the internal electric field in the heterostructure.Though some polarity effects are expectation (for example the piezoelectricity among the FET mixes) in the device of some types, because QCSE, they are not to can expecting based on the reflector of Multiple Quantum Well (MQW).Because the distortion of quantum well, this effect causes red shift in the QW emission, and because electronics and hole wave function separate in the space, also causes the quantum efficiency that reduces.

Recently, the growth of the verified GaN/AlGaN MQW on R plane sapphire (10-12) causes the film (Iyer etc., 2003) along (11-20) direction.(11-20) direction has the polarization vector in the plane of MQW, and this eliminates the internal field perpendicular to quantum well.Therefore, not red shift of emission and the luminous efficiency from this quantum well do not reduce.

Along the utmost point to the nitride model of texture can be grown in (0001) sapphire, (11-20) sapphire and, on 6H-SiC, (0001) ZnO, (111) Si and (111) GaAs.Along the non-utmost point to the nitride sample of texture can be grown on the plane of correspondence of R plane (10-12) and M plane (10-10) sapphire substrates and 6H-SiC and ZnO.Can be by the grow model of this texture of three kinds of deposition processs as previously discussed.

The nitride model of texture can be with the substrate of the growth that acts on efficient LED.Because when growth, spontaneously texture was to a certain degree on the surface, the gradually changing of the refractive index from semi-conductive block to air increased the light escape cone effectively and reduced optical loss via internal reflection.Thereby, more effectively extract light from semiconductor emission, improve the external quantum efficiency of device thus.In identical theme, more effectively absorbing light and they will not need the antireflecting coating of adding to be grown in photo-detector on this model and solar cell.

In addition, because the part of polarity effect suppresses, the nitride surface of texture can also improve the IQE of LED-based III-nitride-based semiconductor MQW.

The GaN model can grow into by the HVPE method has variable surperficial texture.Configuration of surface, reflectivity by studying these models, transport with photoluminescent property can be with they characterizations.Luminous extraction efficiency can be approximate 100%.GaN/AlGaN MQW can be grown on the GaN model level and smooth and texture.Compare with the situation of level and smooth QW, the measurement of the luminescence generated by light on " the tool wrinkle " QW shows that IQE increases significantly, and it ascribes the result that quantum limit Stark effect (QCSE) reduces to because QW be not orthogonal to [0001] utmost point to.The nitride LED structure of incorporating and have " the tool wrinkle " QW into has significantly higher external quantum efficiency than those that use level and smooth quantum well structure.

By reducing the amount of the total internal reflection in the top layer, the extraction efficiency about the photon trajectories of crossing the border is improved on the border of the texture between GaN layer (" top layer ") and the air (or other material).The surface characteristics on the surface of texture can have little characteristic dimension to an about wavelength; Yet bigger texture characteristic is acceptable.Top layer can conformally be grown on the lower level, such as the model of texture.Top layer can, but not necessary, for thousands of

Thick.

By directly on model such as the texture of n type GaN layer, or such as conformally growing or be deposited on growth or deposition GaN layer on the intermediate layer of quantum well (QW) on the model of texture or MQW, can texture GaN layer and air (or other material) between the border.Alternatively, the GaN layer that can grow level and smooth and subsequently can its surface of alligatoring is such as by lithography, even the GaN layer is not to be grown on the surface of texture.This growth back alligatoring can damage the surface of GaN layer.For example, can produce " point defect ".Yet these breaking-ups can be corrected, such as passing through annealing.

MQW can be grown on the n-GaN layer, and the p-GaN layer growth is on MQW then.For example, can be by MBE or MOCVD growth mqw layer.In one embodiment, grown ten pairs of GaN traps and AlGaN build, and it is about 78 that each trap and each are built layer

Thick.In another embodiment, every layer is 50

Thick.Yet the wide scope of the thickness of trap and base layer (comprises less than 50

With greater than 78

) be acceptable.Total thickness of MQW can reach or be higher than 1000

In addition, trap and base layer needn't equate by thickness.For example, 70

The trap layer of (each) can be with 80

The base layer combination of (each).

As point out that the MQW of the texture between n type and the p type GaN layer improves the IQE of P-N knot, improve the amount (or under the situation of photo-detector, the amount of the exterior light of in knot, surveying) of the light that produces by the P-N knot thus.Embodiment can comprise the knot of texture only, the only combination of the top layer of the knot of the top layer of texture or texture and texture.In addition, any of these embodiment can comprise or omit alternatively the QW or the MQW of texture.

The constant diameter of given LED or other semiconductor device or other outside dimension, the P-N knot (being with or without QW or MQW) of texture has bigger surface (contact) area than level and smooth P-N knot in knot.The surface area of this increase can increase the efficient of device.

For lithographic hardmask etc. is aimed at (register) with integrated circuit (IC) wafer, such as the processing step subsequently that is used to relate to wafer, the operator typically light source during by the microscope illumination wafer by the microscopic examination wafer.The optical illumination wafer top surface, make on the wafer alignment mark to the operator as seen.Yet a spot of light is from comprising the device reflection of one or more above-mentioned features.Therefore, using observation by light microscope may be difficult according to the lip-deep alignment mark of the wafer of one or more aspects according to the present invention formation.The difficulty of this observation can cause being difficult to be aligned in the lithographic hardmask of using in subsequently the processing step.In order to overcome this difficulty, according to another embodiment of the present invention, to the operator as seen the edge of light illumination wafer (side) make alignment mark on the wafer etc. thus.Light is from the surperficial transmission of wafer, by microscope, to the operator, rather than as in the prior art from surface reflection.Light source can, it is necessary to take a blame, in the microscope outside.

The present invention also provides novel White LED.LED based on the InGaN/GaN MQW of the texture on the GaN model that is grown in the texture of being produced by HVPE produces two look electroluminescence, obtains white light.For example, can be in the scope of about 2500 ° of K to 7500 ° of K according to the colour temperature of White LED of the present invention, and can change it by change DC injection current.Electroluminescent first peak value is typically in the scope of about 390-450nm, and second peak value is in the scope of about 500-600nm.The color of the two looks emission of combination depends on and is used to drive electroluminescent biasing or injection current.With the increase of injection current, whole color blue shift is owing to the increase from the whole contribution of the peak value in the 390-450nm scope.Believe that the two looks emission according to LED of the present invention derives from the irregularly light emission in two or more difference districts of the MQW of texture.Irregularly the quantum well layer among the MQW of texture has the thickness of at least two differences, because depositing operation causes thick slightly trap floor in flat district and the thin slightly trap floor in the district that tilts.Compare with thicker trap layer, thin trap layer launches and therefore produces the emission peak of blue shift with higher energy.

In one embodiment, will be according to LED of the present invention and change with generation or the full spectrum combination LED device of one or more traditional LED combinations.In another embodiment, can make up two or more and make up the LED device to produce spectrum that change or complete according to LED of the present invention (each has the electroluminescence character such as the difference of colour temperature).

Except that bias current influence, can change the whole electroluminescence spectrum of LED of the present invention by the content that changes In to led color.The amount of the In that exists in any given III-nitride layer of device can change in from least 10% to 100% scope.Increase the red shift that In content causes electroluminescence spectrum.

Variable color feature according to LED of the present invention has several application, comprises being used to make the color image display of variable color indicating device and display, demonstration static images or photo and video image and be used for rest image and the projection device of video.Being used to arrange and control technology and the device that LED according to the present invention produces color image display is being known in the art.For example, in No. 7109957, United States Patent (USP), disclose traditional and driver numeral that is used for the LED image display, by reference it has been incorporated in this.Can change bias current that this control device controls this LED with the color that changes them to produce coloured image.Similarly, the technology that comprises control circuit, software and optics that is used to use led array to produce projecting apparatus is known, and is suitable for using with LED according to the present invention.For example, United States Patent (USP) has been described this LED projecting apparatus for No. 6224216, and by reference it is incorporated in full.

Provide example with example advantage of the present invention in this.Example can comprise or in conjunction with any distortion or the embodiment of the invention described above.Each of the foregoing description also can comprise or in conjunction with the distortion of any or all other embodiment of the present invention.Following example is not to be intended to limit the scope of the invention by any way.

Example I

GaN model by the HVPE growth texture

Make the GaN model of texture by the HVPE technology of above-mentioned change.Fig. 7 shows the electrically excited wafer scale LED that contacts the radiation of 20 places at p.This blue led structure fabrication is on unpolished (0001) sapphire substrates.Grown in this substrate 3 microns heavily doped n type GaN, 10 MQW that then grow, MQW comprise as the InGaN with indium of 13% of trap with as the GaN that builds.The then electronic barrier layer of thin (the about 10nm) of growth behind the growth MQW, electronic barrier layer comprise the AlGaN that contains 30% Al that mixes with magnesium p type, and the GaN of 200nm with the heavy p type doping of magnesium that grow then.Light duplicates the form of unpolished sapphire substrates from its Free Surface that sends.

Fig. 8 a show via HVPE technology when growth of change by scanning electron microscopy (SEM) image of the GaN model of texture irregularly.At sample with respect to electron beam about 30 photographic images when spending that tilt.The growth of GaN layer occurs on (0001) sapphire substrates.Technology via the HCl that uses 25 standard cubic centimeter per minutes (sccm) when 1000 ℃ of preliminary treatment is carried out growth.When about 590 ℃ temperature grown buffer layer, the ammonia that this technology is used and the ratio of III family precursor are 150.1070 ℃ high growth temperature stage, the ratio of the ammonia of use and III family is 60 then.The degree of texture of model or the amount that degree depends on the GaCl that arrives growth front (growth front) have been determined.The amount of this GaCl can also control growing speed.

Compare with Fig. 8 a, Fig. 8 b shows the SEM image of the level and smooth standard GaN layer of atom level.As shown, although some blemish are arranged, the surface topology of traditional GaN layer is a texture not.At sample with respect to electron beam about 30 photographic images when spending that tilt.The luminescence generated by light that will have traditional GaN layer on the level and smooth surface of atom level is compared with the luminescence generated by light of the gallium nitride model of irregularly texture of the present invention.Use the helium cadmium laser of 10 milliwatts (mW) under identical condition, to measure two-layer sample as excitaton source.

Show the result of comparison by Fig. 9, wherein the photoluminescence intensity of the model of texture is bigger 50 times than the intensity of level and smooth GaN layer.The light extraction that strengthens has taken place in the surface of the high index of refraction that especially has this semiconductor layer by texture.Compare with the escape cone of restriction, change by the high index of refraction between GaN layer and the air, the surface of texture has increased the escape cone of single photon.

Among Figure 10 a and the 10b example texture random of III of the present invention family layer model.Figure 10 a is the atomic force microscope images of GaN model of the present invention, is the depth analysis curve in the zone of imaging among Figure 10 b.This curve shows the Gaussian Profile at the surface topology that is characterized as random model.Average peak-paddy surface topology is about 1.3 microns.

Example II

The quantum well of the multiple tool wrinkle of growth on the model of texture

Fig. 6 is the transmission electron microscope image of the lip-deep Multiple Quantum Well that is illustrated in texture (quantum well of tool wrinkle).Quantum well comprises ten couples of AlGaN and GaN layer.Indivedual GaN layers can comprise the quantum well that has as the texture of the AlGaN layer of building layer.The component of AlGaN layer for example is Al _0.2Ga _0.8N.Normally, it is Al _xGa _1-xN.Multiple Quantum Well can also constitute by any combination of little gap III-V nitride film (trap) and big gap III-V nitride film (base).The component of MQW is determined the emitted energy of light, the 6eV from about 0.7eV of pure InN to pure AlN.By any suitable depositing operation a plurality of quantum well layers of growing.MBE technology comprises III family material and passes through radio frequency or the reaction of the nitrogen that microwave plasma activates.Optionally approach is to make III family material and ammonia react in the substrate of heating.

Be used for from the effusion cell evaporation or can provide with the form of III family alkyl by the III family material of growth technique growing semiconductor.When semiconductor growing, in MBE or plasma auxiliary MBE technology, typically use about 1 to 100sccm nitrogen or ammonia.During quantum trap growth, quantum well layer duplicates the texture of model.This MBE technology is known in this area.The present invention also expects other the typical approach that is used for semiconductor growth layer, and it can be used by those skilled in the art.

The quantum well of the texture of the ten couples of AlGaN and GaN has the barrier layer thickness of the correspondence of the thick and about 8nm of the trap of about 7 nanometers (nm).A plurality of quantum well of when substrate is in about 750 ℃ temperature, growing.AlGaN builds on the model that layer at first is grown in III-V of the present invention family texture.Building layer is the surface that is used to deposit quantum well GaN layer then.The GaN layer is then with acting on the growing surface that next builds layer.Can continue this growth pattern, up to forming multiple quantum well layer.Trap duplicates the surface topology of the model of following texture.The thickness of trap and base layer also can be for example from 10

To surpassing 500

Figure 11 and 12 shows traditional quantum well respectively and is grown in the photoluminescence spectrum of the quantum well of the texture on the model of texture of the present invention.The photoluminescence spectrum that is grown in the quantum well on traditional level and smooth GaN layer shows high intensity peak at the 364nm place, and it is mainly owing to the level and smooth block GaN layer below the MQW.Extremely low and wide glow peak at about 396nm is assumed to be owing to level and smooth trap.The cathodoluminescence spectrum of level and smooth trap sample is used to verify this hypothesis.Use the low accelerating voltage of about 4kV to carry out this spectrum, to detect quantum well.The result is illustrated by the illustration of Figure 11.The result has proved that the wide peak value that occurs in the 396nm place is corresponding to traditional quantum well.

As a result, show that the luminous amplitude of observing from level and smooth quantum well reduces greatly and with respect to the block red shift.These results are consistent with QCSE.

Compare with typical quantum well, the photoluminescence spectrum of those traps of the model texture by texture of the present invention is with respect to the luminous spectrum blue shift of block GaN layer.Compare with the model that trap is grown thereon, the trap of a plurality of texture also shows the luminous of basic increase.

These results show that the trap of the tool wrinkle on the III group-III nitride model that is formed on texture is not by the internal field distortion relevant with polarization.Figure 12 also illustrates, and the peak light photoluminescence of the quantum well of texture is bigger about 700 times than the peak light photoluminescence that is grown in those quantum well on traditional level and smooth GaN layer.Difference is owing to the light extraction of the enhancing on the surface by texture with owing to the spontaneous emission of the enhancing of the quantum well of the elimination of QCSE.

Example III

Read aloud the surface of texture of the sample making of over etching mask

In this example, produce the substrate of the texture on surface with texture, extra play is grown on the surface of texture, duplicates the feature of texture simultaneously.Can grow extra play to form model, p-n junction or the optics of the present invention of texture.Extra play can comprise by a plurality of traps and build the Multiple Quantum Well that layer forms.To can be level and smooth or previous texture by the surface of the substrate of texture.The surface of substrate can also be that do not change or opposite natural.

The mask structure that will comprise the gluey particle of the monodispersed sphere of individual layer is coated on the surface of substrate.Substrate can comprise silicon, carborundum, sapphire, GaAs, gallium nitride, aluminium nitride, zinc oxide or glass.Can commercial acquisition magnitude range from 0.02 to 10 micron spherical single disperse gluey particle.The surface that particle is packaged into substrate can be periodic or random, depends on the technology that is used to apply.The coating of the mask structure on one to the five inch diameter part of substrate needs several minutes.This regions coated can limit in the substrate 10 ⁸To 10 ¹²The feature of sub-micron.

Can come the surface of etch mask by for example ion beam etching then.Etching is formed into each other particle in the pillar on the substrate surface.The aspect ratio of pillar is determined by relative mask etching speed and following base material with shape.In order to minimize the aspect ratio of pillar, can use physics and the auxiliary ion beam etching of chemistry.Can pass through then such as the liquid of hydrogen fluoride, chlorine, boron chloride or argon or the surface of gas etching substrate.Owing to the substrate of liquid or gas be etched in some zones not as other zones significantly because pillar often postpones or stop the part of substrate surface to be etched.

After the etching, can be by the pillar on the removal of solvents substrate surface.The dissolution with solvents pillar, generation has the substrate on the surface of texture.Substrate surface can be used in the extra play that the feature of texture is duplicated in growth then.Be used for etching and textured substrate the surface this technology by Deckman etc. at " Molecular-scale microporous superlattices ", describe in detail among the MRS Bulletin, pp.24-26 (1987).

Example IV

Manufacturing and the characteristic of LED on the GaN of texture model

The LED structure is manufactured on the model of the HVPE growth with different texture.Schematically show device architecture among Figure 19.Form the table top of 800 μ * 800 μ by the ICP etching.Transmitted beam hydatogenesis metal contact layer is to n-GaN:Ti (10nm)/Al (120nm)/Ni (20nm)/Au (80nm) with to p-GaN:Ni (5nm)/Au (20nm).The very thick and light of the fraction that in the LED structure, generates of transmission only of Au metal on the mesa top.Show the spectral dependency of two devices among Figure 17 with different surfaces texture as the function of injection current.These data show that by the raising injection current, thereby the light of emission is filled the whole zone of visible spectrum and produced white light.By the visual inspection of emission, observe the different piece that blueness and green emitted are derived from table top.This is that wide green spectral and defective are irrelevant, but with from approx perpendicular to the relevant evidence of emission of the plane QW of polarised direction.Because QCSE, this launches red shift.This explanation is consistent with the 2nd LED with more flat surface.

Example V

Read aloud the HVPE method and in the substrate of C plane sapphire, made thick n-GaN model

Adjust the growth conditions in the method, to obtain having the n type GaN model of configuration of surface that smooths to the multipass degree of complete random texture from atom level.By study these GaN models at the UV and the reflectivity in the visible part of spectrum and their luminescence generated by light (PL) that utilizes that the He-Cd laser excites the characteristic of these models is described.In whole spectral regions, reflectivity is suppressed, to smooth surface approximate 20% to approximate 1% to 2% of the surface of texture irregularly.Compare with the photoluminescence intensity of the GaN model of producing in the same manner and mix similarly with the level and smooth surface of atom level, the photoluminescence intensity of the GaN model of discovery texture is high significantly.The model of the GaN texture that records under the same terms particularly, is to be about 55 with the ratio of the comprehensive luminescence generated by light of the GaN model with smooth surface.Strengthen the light extraction that part ascribes the enhancing on the surface by texture to from the luminescence generated by light of the GaN model of texture irregularly remarkable, it only is 4% that level and smooth surface light is extracted expection, and partly ascribes to owing to the enhancing in the spontaneous emission rate of the localization of the exciton of texture surface.

By the plasma auxiliary MBE on GaN model texture and level and smooth growth phase with GaN/AlGaN MQW (have the trap of 7nm and build wide), and evaluate and test their optical property by luminescence generated by light (PL) and cathodoluminescence (CL).Photoluminescence spectrum level and smooth and " the tool wrinkle " QW has significant difference.The luminescence generated by light of level and smooth quantum well has single peak value at the 396nm place, and because the red shift of the expection of the photoluminescence spectrum of the block GaN film of QCSE is consistent.The luminescence generated by light peak of the QW of tool wrinkle occurs in the 358nm place, and it is with respect to the photoluminescence spectrum blue shift of block GaN film, and this result is consistent with the QW with square configuration.In addition, the comprehensive photoluminescence intensity of many " tool wrinkle " quantum well is than high about 700 times of the comprehensive photoluminescence intensity of smooth M QW.

Strengthen enhancing in the light extraction that part ascribes the surface by texture to from the luminescence generated by light of " tool wrinkle " QW remarkable, and part ascribes the enhancing of spontaneous emission rate to.Increase among the IQE believes owing to the reducing of QCSE because quantum well be not orthogonal to [0001] utmost point to.Further enhancing among the IQE is believed owing to the quantum carrier confinement from " wedge " electronics intrinsic film.The latter originates from the transition in the charge carrier behavior from 2D to 1D, and owing to the crossing plane of the V-arrangement of quantum well, and therefore " wedge " turns round as quantum wire, and this causes the localization and the imprison of exciton.

Example VI

Along the surface of [0001] utmost point to formation III-nitride texture

The model for preparing GaN texture by the HVPE method.The model of GaN texture is grown on the conventional hvpe reactor device of setting up (with reference to Figure 20).In this reactor, synthesize the precursor GaCl of III family (g) in the upstream by the hydrogen chloride (HCl) that on the quartz boat of the Ga that contains the temperature between 500 ℃ to 1000 ℃ of having an appointment, flows.GaCl (g) then in the downstream at sapphire wafer near surface and ammonia (NH ₃) mix with the formation of the temperature between about 900 ℃ to 1200 ℃ GaN, as shown in Figure 20.Reactor is divided into four districts, wherein controls the temperature in each district severally.Reactor also has three transmission pipelines that separate and is used for reactant gas and diluent.Nitrogen and/or hydrogen are as NH ₃Diluent and vector gas with HCl.Nitrogen is also carried by intermediate conduit, wherein it as the gas curtain in downstream or sheath to prevent their premixeds before GaCl and NH3 impact basement surface.

Growing GaN model under the high growth rates condition of the scope of 30-200 μ m/hr (all have level and smooth with surface random texture), growth rate is by 10 to 300 NH ₃The flow rate ratio control of/III family precursor.Use a plurality of technology growth models.One in those is three one-step growth methods, with GaCl (g) preliminary treatment substrate surface or 1000 ℃ temperature nitrogenize sapphire substrates, then at 590 ℃ of GaN resilient coatings that growth is thin.Growth district can be risen to about 1070 ℃ by oblique line then and be used for high temperature GaN growth.Other method is utilized preliminary treatment sapphire surface outside the zinc oxide of sputter before growth.The common thickness of zinc oxide is from about 500

To 1500

Carry out the growth of model by direct heated chamber to begin to grow to growth temperature and flowing reactive thing gas then.

Fig. 8 a shows the SEM image via the GaN model with random texture of HVPE method growth.Utilize three one-step growth technology to carry out this growth, use the HCl of 25sccm when 1000 ℃ of preliminary treatment, the ratio of the NH3/III family that uses when 590 ℃ of grown buffer layers is 150, and the ratio of the NH3/III family that uses when 1070 ℃ of high growth temperatures is 60.Find that the texture degree depends on the amount of the GaCl that arrives growth front, it is control growing speed also.

The reflectivity on the surface of the texture of describing among Fig. 8 a has been shown among Figure 21.As from then on seeing that reflectivity is lower than 1% between 325nm and 700nm among the figure.The reflectivity of this and level and smooth film forms contrast, and it is about 18%.

Fig. 9 shows the light at room temperature photoluminescence (PL) from two GaN films of growing by the HVPE method, and one has the level and smooth surface of atom level, and another has the surface of random texture.Use the HeCd laser of 10mW under identical condition, to measure two films.We can see from these data, and the photoluminescence intensity of sample on surface with texture is bigger 55 times than the photoluminescence intensity of level and smooth film.

Example VII

Luminescence generated by light with GaN model of different surface roughness

Grown GaN model with a plurality of surperficial texture and use the photoluminescence spectrum of measuring them in 244nm emission and power output as the argon ion laser of 20mW.The characteristic of these models has at first been described by atomic force microscope (AFM).Figure 25 to 32 shows the AFM configuration of surface of model VH092403-81 (VH81), VH082504-129 (VH129), VH061603-63 (VH63) and VH080604-119 (VH119) at GaN texture.The r.m.s. roughness of these models changes from 627nm to 238nm.Out of Memory from these data is listed in the comment of figure.

Figure 33 illustrates luminous spectrum at the model of the GaN texture of describing among Figure 25 to 32.What list in the illustration is the r.m.s. roughness and the halfwidth (FWHM) of a plurality of models.

The relation curve of peak strength and r.m.s. roughness has been shown among Figure 34.From these data, significantly, luminous intensity increases with r.m.s. roughness.

For the efficient of the model of GaN texture in the further test light extraction, carried out the relevant photoluminescence measurement of excitation intensity.Figure 22 (a) shows the contrast of the efficient between several models with different texture degree, several models comprise the GaN with level and smooth surface, and Figure 22 (b) shows the measurement of carrying out on the model of the texture with identical carrier concentration and level and smooth film.From then on scheme, high photoluminescence intensity is not tangible owing to high n doping content.

Example VIII

Along the surface of the non-utmost point to formation III-nitride texture

Figure 23 shows the type of the surperficial texture that obtains in the GaN film be grown in R plane sapphire (1-102) by HVPE on.Also can be by this model of growing as the three step process of describing among the example VI.

The reflectivity on the surface of the texture of describing among Figure 23 has been shown among Figure 24.Can see that as figure from then between 325nm and 700nm, reflectivity is lower than 1%.

Example IX

On the GaN model of the texture of growth, forming GaN/AlGaN Multiple Quantum Well (MQW) along the utmost point

In order further to test the ability that on the GaN of texture model, forms the LED structure, 10 couples of GaN/Al0.2Ga0.8N MQW (with reference to Figure 28) on the model VH129 of GaN texture, have been deposited by MBE.Use the RF plasma source of activating molecules nitrogen and the Knudsen effusion cell of evaporation Ga and Al to form MQW.Form a plurality of MQW and Si introduced and carry out the n type in quantum well or base or the two and mix.Alternatively, can use NH3 as the nitrogenous source MQW that grows.Can also be by the MOCVD method similar MQW structure of growing.Similar approach also can be used in the InGaN/AlGaN MQW with various ingredients that grows and is used for launching at the nearly UV and the visible part of electromagnetic spectrum.Figure 35 shows the AFM configuration of surface of the GaN/AlGaN MQW on the model VH129 that is grown in GaN texture.Behind deposition MQW, configuration of surface and texture do not change.In other words, MQW conformally applies the surface of model.

Example X

Along the GaN/Algan Multiple Quantum Well (MQW) of the utmost point on the GaN model of texture of growth Luminescence generated by light

Illustrated among Figure 36 at the photoluminescence spectrum that is grown in a GaN (7nm) Al0.2Ga0.8N (8nm) the MQW structure on the GaN texture model VH082504-129 (Figure 28).As seeing, be higher than the luminous intensity of the model of GaN texture significantly from the luminous intensity of MQW from data.Particularly, the ratio of peak strength is 14.In addition, compare with emission, from the emission blue shift of MQW from the model of GaN texture.

Figure 37 show at texture with the level and smooth GaN model of atom level on the photoluminescence spectrum of identical GaN/AlGaN MQW by MBE growth.Illustration (a) illustrates the photoluminescence spectrum that is grown in the MQW on the level and smooth GaN model with big engineer's scale.From the main peak in the photoluminescence spectrum of level and smooth model owing to luminescence generated by light from model self.Owing to being present in, be suppressed from the luminescence generated by light of MQW along the QCSE of [0001] utmost point in the MQW of growth.Luminous spectrum from the MQW on the level and smooth GaN model has been shown in the illustration (b), and wherein, the surface is detected in use low pressure (4kV) cathodoluminescence (CL) near-earth as far as possible.From illustration, the glow peak of MQW is the center with 396nm.Thereby,, and be 3.50 * 10 from the peak strength of the luminescence generated by light of the MQW on the model of texture if be estimated as approximately 5000 from the number of the counting of the MQW on the level and smooth model ⁶, then ratio is about 700.

In order to understand growth, this sample is carried out the luminous measurement of point cathode from this highly significant in the photoluminescence intensity of the GaN on the model that is grown in GaN texture (5nm) Al0.2Ga0.8N (8nm) MQW.Particularly, the cathodoluminescence spectrum is measured in the flat zone that electron beam is focused on sample ([0001] orientation) approx by as shown in Figure 38 and the zone of inclination.This figure describes along the cross section on the surface of a certain direction.The cathodoluminescence spectrum that obtains at the some A to C shown in Figure 38 has been shown among Figure 39.Figure 39 (a) shows the cathodoluminescence spectrum in arrogant illuminated zone (60 μ m * 40 μ m).Ascribe at two peaks of 356nm and 375nm from be not orthogonal to [0001] utmost point to quantum well (356nm) and almost perpendicular to [0001] utmost point to quantum well (375nm) luminous.With respect to block GaN cathodoluminescence peak (364nm), 356nm peak blue shift, and 375nm red shift.The red shift at 375 peaks and its weak intensity can be by explaining owing to the internal electric field of the polarity effect of twisting MQW.This phenomenon is QCSE.Figure 39 (b) shows the spectrum from the zone of the some illumination on the half flat zone of as shown in Figure 38 MQW.As expection, luminous at 382nm from quantum well owing to the distortion of QCSE.The less peak value at the 359nm place ascribes roughness in the flat surface of miniaturization to and thereby the quantum well surface of fraction is not orthogonal to [0001].Figure 39 (c) shows the cathodoluminescence spectrum that the some B from Figure 38 obtains.In the case, spectrum can be deconvoluted into two peaks, a quantum well emission from the 356nm place, and another is at 364nm, ascribes the emission from the GaN model to.Once more, the data support surface be not orthogonal to [0001] direction the emission of MQW with respect to the block blue shift and have strong luminous (owing to significantly reducing of QCSE).Figure 39 (d) shows the cathodoluminescence spectrum from the some C of Figure 38.Once more, the luminous 356nm place that occurs in, consistent with the QW emission that not influenced by QCSE.

Example XI

On the GaN model of the texture of growth, forming GaN P-N knot LED structure along the utmost point

By MBE is Mg doped p-GaN (hole concentration～10 of～0.5 micron highly conductive with thickness ¹⁸Cm ^-3) be deposited on n type (electron concentration～10 of mixing automatically ¹⁹Cm ^-3Be typical) the GaN model of texture on.The Knudsen effusion cell that the RF plasma source and being used to that use is used for activating molecules nitrogen evaporates Ga and Mg forms p type GaN film.Be grown under the condition that is rich in Ga and take place, it helps the combination at high relatively base reservoir temperature (700 ℃-800 ℃) Mg.Alternatively, can use NH3 as nitrogenous source growing p-type layer.Similarly p type layer can also be by MOCVD or the growth of HVPE method.The wafer scale electroluminescence spectrum of the GaN p-n junction structure of making on the GaN model that Figure 13 shows in texture.This spectrum obtains in room temperature under the electric current of 80mA injects.

Example XII

Growth and the characteristic of GaN/AlGaN MQW LED

The major part of reporting in the document about the work of III-nitride relates to by multiple deposition process these materials of heteroepitaxial growth in (0001) sapphire or 6H-SiC substrate.Be grown in these suprabasil materials and device and contain highdensity line defect (not wrong and counter-rotating border, farmland).In addition, [0001] orientation be in the non-centrosymmetrical wurtzite structure the utmost point to because spontaneous and polarization piezoelectricity, it causes the internal electric field in the heterostructure.Though some polarity effects are expectation (for example the piezoelectricity among the FET mixes) in the device of some types, because QCSE, they are not to can expecting based on the reflector of Multiple Quantum Well (MQW).Because the distortion of quantum well, this effect causes red shift in the QW emission, and because electronics and hole wave function separate in the space, also causes the quantum efficiency that reduces (with reference to Figure 40 a).

Confirmed in self-supporting (10-10) the GaN substrate at GaN/AlGaN MQW with at being grown in the isoepitaxial growth that causes the similar MQW on the sapphire (10-12) (R plane) of [11-20] direction.[10-10] and [10-12] direction all has polarization vector in the plane of MQW.As showing among Figure 40 b, for along the non-utmost point to those of growth, the side of following, the luminescence generated by light peak position trap behavior of AlGaN/GaN MQW, and to along the utmost point to similar MQW, shown significant red shift.To along the QW of the non-utmost point to growth, for surpassing the thick quantum well of 5nm, luminescence emissions efficient is big approximately 20 times.

The growth and the characteristic of the GaN model by HVPE

Cabalu and partner have reported by growth and the characteristic of the GaN of HVPE method, by reference it have been incorporated in full in this.In addition, exercise question with Jasper Sicat Cabalu is " Development Of GaN-Based Ultraviolet And Visible Lightemitting DiodesUsing Hydride Vapor-Phase Epitaxy And Molecular Beam Epitaxy " by reference, and the paper of BostonUniversity (2006) is incorporated in full.

Growing GaN model under the high growth rates condition of the scope of 30-200 μ m/hr (all have level and smooth with surface random texture), it is by the flow rate ratio control of 10 to 300 NH3/III family precursor.At the model growing period, use three one-step growth methods.This is included in 1000 ℃ of GaCl pre-treatment step of carrying out, the then buffering of the temperature low-temperature epitaxy GaN between 550 ℃ to 650 ℃, and the high temperature GaN epitaxial loayer of finally growing.

The characteristic of model is described by scanning electron microscopy (SEM), luminescence generated by light, reflection and Hall effect measurement.Use the He-Cd laser to carry out photoluminescence measurement, and use the xenon lamp of 150W to carry out albedo measurement as wideband light source as excitaton source.

Fig. 8 show level and smooth (Fig. 8 b) and texture (Fig. 8 is the SEM image of GaN model a).At sample with respect to electron beam about 30 photographic images when spending that tilt.Find that the degree of the surperficial texture on the model depends on the amount of the GaCl that arrives growth front, the amount of this GaCl can also control growing speed.The micro-configuration of surface of atomic force of level and smooth GaN model has been shown among Fig. 8 c.Can see from these results, film be atom level level and smooth and its under stepping flow growth pattern, grow.

Figure 41 (a) shows the 100 μ m on the model surface of texture ²AFM scanning.The depth analysis of AFM data (Figure 41 (b)) shows the Gaussian Profile (random distribution) of surface roughness.Produced from the GaN model with kinds of surface texture degree of the mean depth scope of 800nm to 3 μ m.

The reflectivity of the model of the texture of describing among Fig. 8 a that records is lower than 1% between 325nm and 700nm.That is to say that almost all incident lights from wideband light source are coupled in the model of GaN texture.With the reflectivity contrast of itself and level and smooth film, the latter is about 18%.

Illustrated among Figure 42 the electron mobility of model of the texture of research and the relation curve of electron concentration.Can see that from data these GaN models all are doped to the n type automatically and therefore are suitable for end contact layer among the GaN LED by heavy.

Show light at room temperature photoluminescence (PL) by Fig. 9 from two the GaN models (has the level and smooth surface of atom level, and another has the irregularly surface of texture) by HVPE method growth.Use the He-Cd laser of 10mW to measure two samples under the same conditions.The peak photoluminescence intensity of sample on surface with texture is than approximate 55 times greatly of the photoluminescence intensities of the sample with smooth surface.

Partly ascribe the enhancing of the light extraction on the surface by texture to from the remarkable enhancing of the photoluminescence intensity on the GaN surface of texture irregularly.Because the random texture on surface, the escape possibility of single photon has increased, because escape cone is not limited to the refractive index by semiconductor and air limits that.This is because the refractive index in the model of texture gradually changes to 1 (corresponding to air) from being worth 2.5 (corresponding to GaN) along optical axis.In other words, owing to,, have available additional escape angle to the photon of each emission at the interface random texture.This is similar to the transmission by diffraction grating, wherein, grating make incident wave produce phase shift and the wavelength that depends on incident light [9] at specific angular bend wavefront.In the case, change (or cycle " surperficial texture ") control phase shift by cycle at the thickness of grating/air interface place grating material.Under the situation of the GaN of texture model, surperficial texture is not the cycle, but random, and this crosses the interface and produces random phase shift.This angle randomization that causes escaping has improved photon escape possibility effectively.Thereby surperficial texture is allowed more escape angle, its not as use as Figure 43 b in the critical angle of level and smooth interface definition of example.

If the extraction efficiency from the luminescence generated by light of the emission of the GaN model of texture is 100%, then when the model of level and smooth model of supposition and texture has equal IQE, should be 25 from the ratio of the photoluminescence intensity of the model of texture and level and smooth model.Yet the data that illustrate here show that this ratio equals 55.The IQE of the GaN model of this hint texture should be at least than the high twice of IQE of level and smooth GaN model.From the IQE of the model of texture in fact should be than the IQE of level and smooth model the big factor more than two because just in time be 100% to be impossible from the extraction efficiency of the model of texture.In theory, with the surface-associated of texture unordered cause to a certain degree potential fluctuation and therefore exciton be trapped in the local gesture minimum value.This causes the spontaneous emission possibility that strengthens, owing to the exciton localization.

By MBE in growth and characteristic with the GaN/AlGaN MQW on the GaN model of variable surperficial texture

Cabalu etc. have described in growth and characteristic with the GaN/AlGaNMQW on the GaN model of variable surperficial texture, in view of the above it are incorporated in full.

On GaN model texture and level and smooth, deposited ten couples of GaN/Al0.2Ga0.8N MQW 750 ℃ base reservoir temperature by MBE, wherein the thick 7nm of trap, build thick 8nm.The AFM of MQW on the model of texture studies show that MQW conformally applies the GaN model of texture.

Illustrated among Figure 44 near the x ray diffraction pattern (0002) Bragg peak value of ten cycle GaN (7nm) on the model that is grown in GaN texture/Al0.2Ga0.8N (8nm) MQW.This illustrates the further evidence that can form MQW on such as the model by the shown irregularly texture of profile at elementary and higher superlattice peak.In addition, the observed result at these peaks shows unexpected interface between AlGaN base and GaN trap.Figure 44 also shows the analog result of using the kinematics scattering model.Suppose that AlGaN builds and the GaN trap has equal growth rate, analog result is determined the cycle of 15.4nm, and is wide corresponding to the base of 8.2nm wide with trap 7.2nm.From the position at zero level superlattice peak and supposition Vegard law this material system effectively, the Al component during AlGaN builds is defined as～20%.Target thickness when these values meet growth (8nm builds wide and the 7nm trap is wide) and alloy compositions (20%Al).

Show the photoluminescence spectrum of the MQW that grows on the comfortable GaN model level and smooth and texture among Figure 11 and 12 respectively.From the photoluminescence spectrum that is grown in the MQW on the level and smooth GaN model (Figure 11) mainly illustrate from the GaN model at the luminescence generated by light at 364nm place with at the minimum and wide glow peak at about 396nm place.In addition, by using cathodoluminescence spectrum that low accelerating voltage (4kV) measures same sample to verify luminous owing to from QW of this small peak to detect QW.These data have been shown in the illustration of Figure 11.In fact, except at the 364nm place from GaN model luminous, wide peak appears at 396nm, it is corresponding to the cathodoluminescence from QW.Thereby,, significantly reduce from luminous red shift and the amplitude of QW with respect to block.These results meet quantum limit Stark effect (QCSE) because these QW perpendicular to [0001] utmost point to.

Figure 12 shows the photoluminescence spectrum from the MQW on the GaN model that is grown in texture.Be relatively, at the identical photoluminescence spectrum that there is shown from the GaN model of texture.Importantly, note also being significantly higher than luminous intensity with respect to block GaN photoluminescence spectrum blue shift and luminous intensity from the GaN model of texture from the photoluminescence spectrum of MQW.These results are consistent with square quantum well.In other words, because the quantum well on the GaN of texture model is not vertical with [0001] direction, they are not by the internal field distortion relevant with polarization.

Directly comparison shows that from the photoluminescence intensity of " the tool wrinkle " MQW of the peak light photoluminescence of MQW among Figure 11 and Figure 12 is recently high 700 times from the photoluminescence intensity of level and smooth MQW.Significantly strengthen part from this of the luminescence generated by light of " tool wrinkle " QW and ascribe the enhancing of light extraction on the surface by texture and the enhancing that part ascribes spontaneous emission rate to.If supposition owing to from the enhancing of the light extraction on the surface of texture recently from the factor of the enhancing on level and smooth surface high 25, then have approximate 30 additional factor, its inevitable enhancing owing to spontaneous emission rate.Growth among the evidence hint IQE that early discusses reduces owing to QCSE's because quantum well be not orthogonal to [0001] utmost point to.Further enhancing among the IQE is also expected owing to the quantum carrier confinement from " wedge shape " electronics eigen mode.The latter originates from the transition in the charge carrier behavior from 2D to 1D, and owing to the crossing plane of the V-arrangement of quantum well, and therefore " wedge " turns round as quantum wire, and this causes the localization and the imprison of exciton.

Example XIII

The forming fluorescence-free White LED

This example is described and is not used the method for making GaN base White LED or multiple color LED such as the reflector of fluorophor.

Figure 14 a shows the spectrum from the commercial White LED of the single DS25 of technical data of LumiLeds.This White LED is based on the nitride LED structure, its at the emission of approximate 430nm place and excitation-emission peak at the YAG of the broadband spectral at 550nm place fluorophor.Make based on the LED structure growth of the InGaN/GaN MQW of texture on the GaN model of the texture of producing by HVPE.The sort of shown in these LED and Figure 14 a has similar spectrum, do not use fluorophor.

Figure 14 b shows the electroluminescence spectrum of this LED.Under the DC of 30mA injection current, record this spectrum.Though do not use fluorophor to be used to be created on the broadband emission at 537nm place, the commercial White LED shown in these spectrum and Figure 14 a has significant similitude.Figure 14 c shows LED, and its spectrum is shown among Figure 14 b, uses the DC injection current of 25mA.

These two peak-to-peak relative intensities depend on electric current injection level.The high energy wave band increases with bias current.Identical LED can produce different colors, because color depends on the relative ratios of two wave bands.In Figure 15 a-15c, presented the spectrum of other LED device that shows similar behavior.

Figure 16 shows the photo of the LED structure that obtains under the DC injection of describing in as Figure 15 b.As expected, LED has absinthe-green color, because green wave band more is dominant.Yet, some part emission blue light of wafer.

In Figure 17, two different LED have been demonstrated the dependence of electroluminescence spectrum to the DC injection current.The LED on the right has the major part on flat surface.

Example XIV

Use MBE to make the model of texture

Make the GaN model by the plasma auxiliary MBE, wherein gallium and Nitrogen Atom reaction by dinitrogen is obtained by plasma source.Two samples are all 825 ℃ of growths.Nucleation is identical, and (Figure 45 a) and the surface (Figure 45 b) that causes random texture of the growth under rich nitrogen condition (flow of the flow-rate ratio gallium of the nitrogen of activation is much bigger) except the growth under rich gallium condition (flow of the nitrogen that the flow-rate ratio of gallium activates is much bigger) causes level and smooth surface.

Example XV

QCSE is to the dependence of quantum well layer thickness

Because expection QCSE depends on the width of quantum well layer, so research thickness is 5.5 and the PL spectrum of the quantum well layer of 7.0nm.Figure 46 a and 46b show the wide relation curve of emission peak and luminous intensity and trap at level and smooth respectively with GaN/Al0.2Ga0.8N texture.As seeing among Figure 46 a, with respect to block GaN emission, from the PL spectral red shift of smooth M QW, and from those blue shifts a little of the MQW of texture.Accordingly, narrow down, increase, and have only a little growth, as shown in Figure 46 b from the PL intensity of the MQW of texture from the PL intensity of smooth M QW with trap is wide.These results are consistent qualitatively with QCSE.

Example XVI

The internal electric field in the quantum well layer and the influence of polarization

By the transition from the charge carrier behavior of 2D to 1D (and 0D) potentially, can explain the enhancing in the spontaneous emission at the part place of the inclination of quantum well layer owing to the crossing plane of the V-arrangement of quantum well.Thereby the part of inclination can operate as quantum wire (or quantum dot), causes the localization and the imprison of exciton.In addition, owing to the polarization components that is parallel to quantum well layer, as shown in Figure 47 a, can be expected at the electron accumulation at place, intersection quantum well plane, as shown in Figure 47 b.Depend on the balancing charge density in these crosspoints, the enhancing in the spontaneous emission can be derived from plasma effect.

Though described the present invention in conjunction with the preferred embodiments in this, reading the above stated specification postscript, those skilled in the art can implement to change, be equal to alternative and other change for the Apparatus and method for of this proposition.Above-mentioned each embodiment also can comprise or in conjunction with as about disclosed this variation of any or all other embodiment.Therefore the protection of authorizing of expectation the patent certificate here is only by being included in any range that is equal to the definition in substituting of claims and its.

Reference

Cabalu?et?al.，“Enhanced?Light?Extraction?and?Spontaneous?EmissionFrom?Textured?GaN?Templates?Formed?During?Growth?by?the?HVPE?Method”，State?of?the?Art?Program?on?Compound?Semiconductors?XLI?and?Nitride?andWide?Bandgap?Semiconductors，Sensors?and?Electronics?V，ElectrochemicalSociety?Proceedings，Vol.2004-06，pp.351.

Cabalu?et?al.，“Enhanced?Light?Extraction?and?Spontaneous?EmissionFrom“Wrinkled”Quantum?Well?Grown?By?Plasma-Assisted?MolecularBeam?Epitaxy(PAMBE)”，Presented?at?the?22nd?North?America-MolecularBeam?Epitaxy?Conference，Banff，Alberta，Canada，October?10-13，2004，p.110.

Iyer?et?al.，“Growth?and?Characterization?of?Non-polar(11-20)GaN?andAlGaN/GaN?MQWs?on?R-plane(10012?Sapphire”，Mater.Res.Soc.Symp.Proc.，Vol.743，pp.L3.20(2003).

Ryu?et?al.，“”，IEEE?Journal?of?Selected?Topics?in?Quantum?Electronics，Vol.8，NO.231(2002).

Tsao，J.，“Light?Emitting?Diodes(LEDs)for?General?Illumination”，AnOIDA?Technology?Roadmap?Update(2002).

Windish?et.al.，“40％?efficient?thin?film?surface?textured?LEDs?byoptimization?of?natural?lithography”，IEEE?Trans.Electron?Devices，Vol.47，NO.1492(2000).

Claims

1, a kind of semiconductor device as reflector, this device comprises:

Substrate comprises the material that is selected from the group that comprises sapphire, carborundum, zinc oxide, silicon, GaAs, gallium nitride, aluminium nitride and aluminum gallium nitride;

At described suprabasil ground floor, comprise the III-nitride-based semiconductor, wherein, the surface of this ground floor has the irregularly topology of texture, and this ground floor is that the n type mixes, and this ground floor is electrically connected to first make contact;

With build layer alternately and by one or more quantum well layers of this surface texture of this ground floor, this bases layer comprises that III-nitride-based semiconductor and this quantum well layer comprise the III-nitride-based semiconductor; And

Comprise the III-nitride-based semiconductor than the upper strata, wherein, should be than the surperficial texture of upper strata by adjacent quantum well layer, should be that the p type mixes than the upper strata, and should be electrically connected to second contact point than the upper strata; Wherein, by between described first and second contact points, control the electroluminescence spectrum of this device via this device by electric current.

2, semiconductor device as claimed in claim 1, wherein, described substrate be irregularly surperficial texture and described ground floor and layer copy substrates texture subsequently.

3, semiconductor device as claimed in claim 1, wherein, this substrate comprises the material that is selected from the group that comprises (0001) sapphire, (10-12) sapphire, (10-10) sapphire, (11-20) sapphire, (0001) carborundum, (0001) zinc oxide, (111) silicon, (111) GaAs, (0001) gallium nitride and (0001) aluminium nitride and (0001) AlGaN.

4, semiconductor device as claimed in claim 1, wherein, this substrate is included in the surface of the texture on the side of described ground floor.

5, semiconductor device as claimed in claim 1, wherein, this substrate is included in the surface away from the texture on the side of described ground floor.

6, semiconductor device as claimed in claim 1, wherein, this substrate is included in the polished surface on the side of described ground floor.

7, semiconductor device as claimed in claim 1, wherein, by this surface of lithography or this substrate of etching texture.

8, semiconductor device as claimed in claim 1, wherein, this ground floor is at this suprabasil deposit, and its combination by a kind of or these methods in hydride gas-phase epitaxy, metal-organic chemical vapor deposition equipment, molecular beam epitaxy, liquid phase epitaxy, the laser ablation obtains.

9, semiconductor device as claimed in claim 8, wherein, this ground floor is the result of the hydride gas-phase epitaxy of the III-nitride semi-conductor material when having excessive HCl thereon.

10, semiconductor device as claimed in claim 9, wherein, NH in this hydride gas-phase epitaxy technology ₃With the molar ratio of HCl from 5:1 to 10:1.

11, semiconductor device as claimed in claim 9, wherein, this quantum well layer and base layer are the results of molecular beam epitaxy.

12, semiconductor device as claimed in claim 8, wherein, this ground floor is the result of N molecular beam epitaxy when having molar excess with respect to Ga.

13, semiconductor device as claimed in claim 1, wherein, one or more quantum well layers are by a kind of growth in the combination of hydride gas-phase epitaxy, metal-organic chemical vapor deposition equipment, molecular beam epitaxy, liquid phase epitaxy, laser ablation or these methods.

14, semiconductor device as claimed in claim 1, wherein, this electroluminescence spectrum of this device comprises two or more peaks.

15, semiconductor device as claimed in claim 14, wherein, Multiple Quantum Well comprises the dispersion zone of the quantum well layer with different-thickness.

16, semiconductor device as claimed in claim 15, wherein, the quantum well bed thickness of quantum well layer ratio in the district of the inclination of this Multiple Quantum Well in the flat district of this Multiple Quantum Well.

17, semiconductor device as claimed in claim 14, wherein, in the described peak one in the scope of 390-450nm and another peak in the scope of 500-600nm.

18, semiconductor device as claimed in claim 14 wherein, increases via the electric current of this device between described first and second contact points and is increased in a place in the described peak with respect to the electroluminescence at another place.

19, semiconductor device as claimed in claim 18, wherein, the peak of increase is in the scope of 390-450nm.

20, semiconductor device as claimed in claim 18, wherein, by increasing via the electric current of this device between described first and second contact points this electroluminescent colour temperature of blue shift.

21, semiconductor device as claimed in claim 1, its electroluminescence is white.

22, semiconductor device as claimed in claim 1, its electroluminescent characteristic are that colour temperature is in the scope of 2500 ° of K-7500 ° of K.

23, semiconductor device as claimed in claim 1 also comprises fluorophor.

24, semiconductor device as claimed in claim 23, wherein, the emission peak of this fluorophor is in the scope of 500-700nm.

25, a kind of method of controlling the emission spectrum of light-emitting diode may further comprise the steps:

Light-emitting diode is provided, comprises:

Comprise the III-nitride-based semiconductor than the upper strata, wherein, should be than the upper strata by surperficial texture apart from this ground floor quantum well layer farthest, should be that the p type mixes than the upper strata, and should be electrically connected to second contact point than the upper strata; And

Between described first and second contact points, pass through electric current via this device; Wherein, control the electroluminescence spectrum of this diode by described electric current.

26, method as claimed in claim 25, wherein, this electroluminescence spectrum of this diode comprises two or more peaks, and increases via the electric current of this device between described first and second contact points and be increased in a place in the described peak with respect to the electroluminescence at another place.

27, method as claimed in claim 26, wherein, this electroluminescence at the place, peak in the 390-450nm scope increases with respect to one or more other peaks.

28, method as claimed in claim 26, wherein, by increasing via the electric current of this device between described first and second contact points this electroluminescent colour temperature of blue shift.

29, a kind of indicating device of variable color comprises:

Semiconductor device as claimed in claim 1; And

Controller is used to respond the input signal setting via the electric current of this device between described first and second contact points, and wherein, the variation in this input signal causes by the variation in the color of the light of this device emission.

30, a kind of illuminating device of variable color comprises:

One or more semiconductor device as claimed in claim 1; And

Controller is used to respond one or more input signal settings via the electric current of each this device between described first and second contact points, and wherein, the variation in this input signal causes by the light intensity of this semiconductor device emission and the variation in the color.

31, illuminating device as claimed in claim 30, wherein, a plurality of described semiconductor device are arranged in the array.

32, illuminating device as claimed in claim 30 comprises a plurality of described semiconductor device, and wherein each semiconductor device is controlled independently.

33, illuminating device as claimed in claim 30 comprises a plurality of described semiconductor device, and wherein this semiconductor device is as one man controlled.

34, a kind of two-dimentional color monitor comprises:

Two-dimensional array comprises a plurality of semiconductor device as claimed in claim 1; And

Controller is used to respond the input signal setting via the electric current of each semiconductor device between described first and second contact points, and wherein, this input signal causes forming by the multicolour pattern of the light of this semiconductor device emission.

35, color monitor as claimed in claim 34, wherein, this multicolour pattern forms the image that can see by watching this array.

36, display as claimed in claim 35, it forms rest image.

37, display as claimed in claim 35, it forms moving image.

38, a kind of projecting apparatus comprises:

Controller is used to respond the input signal setting via the electric current of each semiconductor device between described first and second contact points, and wherein, this input signal causes forming by this semiconductor device multicolour pattern emission and that be projected onto the light on the view screen.

39, projecting apparatus as claimed in claim 38, wherein, this multicolour pattern forms image on this view screen.

40, projecting apparatus as claimed in claim 38, it is the rest image projecting apparatus.

41, projecting apparatus as claimed in claim 38, it is the moving image projecting apparatus.

42, a kind of multilayer semiconductor device of integral body, can be energized with the wavelength of launching a plurality of differences and have at least one quantum well layer, each trap layer has the variable thickness of growing thickly about the one-tenth-value thickness 1/10 of at least two differences, and the thickness of each difference is relevant with the wavelength of difference.

43, a kind of variable color indicating device comprises:

Semiconductor device as claimed in claim 42; And

Controller is used to respond the electric current of input signal setting via this device, and wherein, the variation in this input signal causes by the variation in the color of the light of this device emission.

44, a kind of variable color illuminating device comprises:

One or more semiconductor device as claimed in claim 42; And

Controller is used to respond the electric current of one or more input signal settings via each this device, and wherein, the variation in this input signal causes by the light intensity of this semiconductor device emission and the variation in the color.

45, a kind of two-dimentional color monitor comprises:

Two-dimensional array comprises a plurality of semiconductor device as claimed in claim 42; And

Controller is used to respond the electric current of input signal setting via each semiconductor device, and wherein, this input signal causes forming by the multicolour pattern of the light of this semiconductor device emission.

46, a kind of projecting apparatus comprises:

Controller is used to respond the electric current of input signal setting via each semiconductor device, and wherein, this input signal causes forming by this semiconductor device multicolour pattern emission and that be projected onto the light on the view screen.