CN101587927B - Light-emitting element and method for manufacturing same - Google Patents
Light-emitting element and method for manufacturing same Download PDFInfo
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- CN101587927B CN101587927B CN2008101005079A CN200810100507A CN101587927B CN 101587927 B CN101587927 B CN 101587927B CN 2008101005079 A CN2008101005079 A CN 2008101005079A CN 200810100507 A CN200810100507 A CN 200810100507A CN 101587927 B CN101587927 B CN 101587927B
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Abstract
The invention discloses a light-emitting element and a method for manufacturing the same. The light-emitting element is a semiconductor element comprising a growth substrate. An n-shaped semiconductor layer, a quantum well active layer, a p-shaped semiconductor layer and other epitaxial structures are formed on the growth substrate in sequence, and the quantum well active layer is made to have a photonic crystal with two-dimensional periodical dielectric constant change or material constitution change on the basis of the holography exposure technology and the internal diffusion effect of a quantum well without adopting the etching technology. The structure of the photonic crystal is formed from the internal diffusion effect caused by combining with two incident lights on the basis of the holography exposure technology to interfere in the quantum well active layer. The light-emitting element having the photonic crystal not only can increase the internal diffusion effect, but also can increase the light emitting efficiency.
Description
Technical field
The present invention relates to structure of a kind of light-emitting component and preparation method thereof.
Background technology
The application of semiconductor light-emitting elements is rather extensive, for example can be applicable to traffic signals sign, Blue-DVD high density storage, HD-DVD, green glow RCLED (applicable to the internal communication and the control system of automobile-used fiber optic fibers, plastic) and medical treatment device (UV LEDs) etc.The lifting of light-emitting component usefulness, the aspect that light-emitting component is used is more extensive, for example can be applicable to optical display (RGB edge-lit back light units) or back projection TV (Rear-projection TV).Therefore, lift elements usefulness is present main research topic.
Because of light-emitting diode luminous do not have directivity, in the application of optical module, because the influence of light exhibition amount (Etendue), the light service efficiency also is restricted.Therefore making lumination of light emitting diode have directivity, and then reduce the angle of divergence, also is one of lifting mode of light-emitting diode usefulness.It is the medium of periodic arrangement that E.Yablonovitch and S.John proposed to have with electromagnetic wavelength yardstick 1/2 in 1987, just far infrared is to wavelength of visible light size (300～700nm), can make that electromagnetic wave can be by the space structure of medium just like as electronics is in crystal in this behavior that has in the material of highly arranging order, the arrangement cycle, version and dielectric constant are controlled, therefore do not need to change the chemical constitution of medium itself, only need to design just and can produce element with different light characteristics at the wavelength dimension of medium and photonic bandgap, the new-type artificial lens of this kind be called photonic crystal (Photonic Crystal, PC).If be applied in light-emitting diode, go out the hole shape structure of 2 D photon crystal in its surface etching, can make the light that is limited in the light-emitting diode no longer launch, significantly increase photoconduction launching opportunity upward, and then reduce the light-emitting diode angle of divergence and promote its efficient to any direction.
Its composition of photonic crystal can present periodic variation on the x-y plane, and this structure with two-dimentional equivalent refractive index viewed in plan, as shown in Figure 1, is presented the equivalent refractive index of this structure, wherein n with two-dimensional approach
1Be the refractive index after the quantum well diffusion inside effect, n
2Be the refractive index before the quantum well diffusion inside effect.We are with equivalent refractive index difference (n
1-n
2) be defined as Δ n,
Δn＝n
r+j*n
i (1-1)
N wherein
rBe the real part of equivalent refractive index difference, n
iImaginary part for the equivalent refractive index difference.Active layer material is formed and is presented periodic variation, its n
rWith n
iTwo parameters can exist simultaneously.n
rWhat influence is that light emitting diode light takes out efficient (light extraction efficiency), n
iValue then can influence light-emitting diode internal quantum efficiency (internal efficiency).The known practice is to etch 2 D photon crystal at LED surface to form similar two-dimentional equivalent refractive index plane, but only there is n in its Δ n
r(n
iBe zero), so can only influencing the light of light-emitting diode, this structure takes out the efficient and the angle of divergence.
Another known practice is to use conventional laser holography exposure device (Laser holography apparatus), and utilize semiconductor technology exposure, development and etching method on the ohmic contact layer of light-emitting component, to form nanoscale island structure (nano-sized islands), take out efficient with the light that increases light-emitting component.
Summary of the invention
The invention provides a kind of light-emitting component, comprise: substrate with photon crystal structure; And the semiconductor epitaxial structure is positioned on this substrate, wherein this semiconductor epitaxial structure has mqw active layer, and this mqw active layer is included in one dimension or two-dimensional space has the periodically photon crystal structure of change in dielectric constant, and this photon crystal structure only is formed in this mqw active layer.With the light-emitting diode is example, and the composition of its active layer material can present periodic variation at X-Y plane, and the internal quantum efficiency and the light that can increase light-emitting diode simultaneously take out efficient.In addition, the cyclic variation of its refractive index occurs in active layer, rather than LED surface, according to the distribution scenario of photon, this photonic crystal light-emitting diode only needs the refractive index variable quantity of trace can effectively promote its internal quantum efficiency and light takes out efficient.
Description of drawings
Fig. 1 is that the composition that shows its gain region material of light-emitting diodes can present periodic variation diagram at X-Y plane;
Fig. 2 is the novel holography exposure system structure chart that shows the present invention's design;
Fig. 3 shows that incident light of the present invention causes local quantum melange effect figure;
Fig. 4 a can be with distribution map before showing quantum well diffusion inside effect;
Fig. 4 b can be with distribution map after showing quantum well diffusion inside effect;
Fig. 5 shows distribution of light intensity distribution map of the present invention;
Fig. 6 a is the light emitting diode epitaxial structure figure that shows the embodiment of the invention;
Fig. 6 b is the photonic crystal light-emitting diode that shows the embodiment of the invention;
Fig. 7 shows that active layer is formed with the X-direction distribution map in the embodiment of the invention light-emitting diode;
Fig. 8 is the photonic crystal light-emitting diode texture edge figure that shows the embodiment of the invention.
Description of reference numerals
1 growth substrate, 2 n type semiconductor layer
3 multi-quantum pit structures, 4 p type semiconductor layer
Composition after the composition 6 quantum well diffusion inside effects before the 5 quantum well diffusion inside effects
7 current spreading layer, 8 n type electrodes
9 p type electrodes, 201 LASER Light Source (laser source)
202 1 to 10 spectroscopes (splitter), 203 1 to 1 spectroscopes (splitter)
204 100% ultraviolet light microscopics (UV mirror), 205 power supply monitors (power monitor)
206 automatic gates (automatic shutter)
207 twin shaft electric controllers (X-Y motion controller)
208 wafer holder swivel mounts (rotation stage)
209 circulator A (rotator), 210 circulator B (rotator)
211 wafer test piece a incident lights 1
B incident light 2 c highlight strength zones
D low light intensity area d
1The distance of 1 to 1 spectroscope and 100% ultraviolet light microscopic
E
cThe conduction band ENERGY E
vValency electricity band energy
E
g, E
g' can be with difference n
1Refractive index after the quantum well diffusion inside effect
n
2Refractive index before the quantum well diffusion inside effect
The angle of the cycle Ψ secondary quantum well diffusion inside effect of Λ light intensity distributions
Embodiment
For fear of etching process active layer zone in the epitaxial structure is damaged, existing with as shown in Figure 2 a novel holography exposure system explanation embodiment of the invention.Replace light extensor (Beam Expander) in the legacy systems with 1 to 1 spectroscope (Splitter) 203, and wafer holder swivel mount 208 is located on the accurate twin shaft electric controller (X-Y Motion Controller) 207.Twice incident light a and b with optical path difference can form the periodic light intensity distributions of one dimension on LED wafer 211 surfaces, as shown in Figure 3.The periods lambda of light intensity distributions can be determined by the 1-2 formula.Wherein, λ
LaserBe Wavelength of Laser, d
1Be the distance of 1 to 1 spectroscope and 100% ultraviolet light microscopic, n is the optical path difference factor that beam split caused, and m is the exponent number of the twice interference of light, and n and m are integer.
λ
Laser＝2m[(d
1/λ
Laser)-n-Λcosθ] (1-2)
Before the making, twice incident Light Interference Streaks must be embedded in (fixedly θ and m=1) on the photoresist, and measure interference periods Λ, the anti-optical path difference factor of n that pushes away by AFM, change angle θ decision periods lambda by circulator A (Rotator) 209 again, wherein θ can be between the 20-80 degree.
The present invention uses the twice incident light to interfere, and the cycle of reaching is the intensity variation of 200nm～1000nm, again by control luminous intensity and the length of incident light time, with control energy gap variable quantity and change of refractive amount in various degree.When incident light penetrates the limiting layer of photoelectric cell and absorbed by quantum well, make the quantum well part heat up rapidly, cause each inner composition atom to become unstable because of heat absorption, when the heat energy of atom hyperabsorption, can shake off the covalent bond of constraint originally, beginning is toward concentration lower diffusion, this effect be called quantum well diffusion inside effect (Quantum Well Interdiffusion, QWI).Generally speaking, the energy band diagram of quantum well is that (as Fig. 4 a), after through the diffusion inside effect, the distribution of being with of quantum well is more level and smooth circular shape (as Fig. 4 b) to rectangle trap shape, and can be with difference E in the active layer
g' also become bigger.Emission wavelength moves toward short wavelength's direction, and refractive index also can diminish thereupon.The twice incident light is interfered can produce one dimension and equal light intensity distributions of cycle, if will make 2 D photon crystal, can carry out twice and interfere step, and the circulator B (Rotator) 210 that utilizes Fig. 2 determines the angle Ψ (can between the 20-90 degree) of twice quantum well diffusion inside effect, simultaneously by the control luminous intensity, the zone (staggered place) of repetition quantum well diffusion inside effect is had than macro-energy poor (as the c point zone of Fig. 5), and then produce the change of refractive amount.This variable quantity has two-dimensional space periodically, and this two-dimentional cycle does not need unanimity.When legal system was made the 2 D photon crystal light-emitting diode according to this, the time difference that needs to be separated by between twice interference of control influenced quantum well diffusion inside effect to avoid the time difference after causing cooling for a long time.In addition, also can on the carrier of LED wafer, heat, promote the effect of quantum well diffusion inside effect.The size of general laser beam is about the 1mm grade, can cause the area of quantum well diffusion inside effect limited, therefore in another embodiment, be that LED wafer bearing swivel mount is located on the accurate twin shaft electric controller, make large-area photonic crystal light-emitting diode in step-type mode, shown in Fig. 6 b.To be light-emitting component form (y) with the X-axis distribution scenario through the active layer after quantum well diffusion inside effect to Fig. 7.Because light energy distribution can present the variation situation of cycle and gradual change with space (X-Y), so form the variation situation that (y) also can present cycle and gradual change with space (X-Y) through the active layer after the secondary quantum well diffusion inside effect, and then increase the some optical confinement (optical confinement) and electric current restriction (current confinement) of light-emitting diode.
(embodiment one)
Shown in Fig. 6 a, at growth substrate 1, its material can be GaAs, silicon, carborundum, aluminium oxide, indium phosphide, gallium phosphide, aluminium nitride or gallium nitride etc., and the limiting growth substrate is not transparent substrates or extinction substrate; With the organometallic chemistry vapour phase epitaxy method in regular turn growing n-type semiconductor layer 2 (as n-GaN, n-AlGaInP), multiple quantum well active layer 3 is (as InGaN, AlGaInP), p type semiconductor layer 4 is (as p-GaN, layer such as p-AlGaInP), to form light emitting diode epitaxial structure, wherein n type semiconductor layer, p type semiconductor layer can be used as limiting layer.Utilize the novel holography exposure system structure of Fig. 2 again, the twice incident light is directly beaten in light-emitting diode total surface formation interference fringe, as selected laser source wavelength (λ between limiting layer 4 (p type semiconductor layer) and 3 corresponding wavelength of multiple quantum well active layer structure
Cladding＜λ
Laser＜λ
QW), incident light can penetrate limiting layer (p type semiconductor layer) and be absorbed by multiple quantum well active layer, make local quantum well heat up rapidly, cause each composition atom of chip internal to become unstable because of heat absorption, when the heat energy of atom hyperabsorption, can shake off the covalent bond of constraint originally, beginning produces quantum well diffusion inside effect toward the diffusion of concentration lower.This twice incident light is interfered can reach the intensity variation that the cycle is 200nm-1000nm, and again by control luminous intensity and the length of incident light time, may command energy gap in various degree changes and the change of refractive amount.Utilize circulator (Rotator) B to determine the angle Ψ (can between the 20-90 degree) of twice quantum well diffusion inside effect more on demand, same by the control luminous intensity, it is poor than macro-energy that the zone (staggered place) of repetition quantum well diffusion inside effect is had, and then produce the change of refractive amount.This variable quantity has two-dimensional space periodically, and this two-dimentional cycle do not need unanimity, promptly form photonic crystal light-emitting element (as Fig. 6 b).On the p type semiconductor layer, form current spreading layer 7 again, by current spreading layer after be etched down to the n type semiconductor layer, on current spreading layer and n type semiconductor layer, form p type electrode 9 and n type electrode 8 respectively, promptly form the photonic crystal light-emitting diode element, as shown in Figure 8.
(embodiment two)
Shown in Fig. 6 a, at growth substrate 1, its material can be GaAs, silicon, carborundum, aluminium oxide, indium phosphide, gallium phosphide, aluminium nitride or gallium nitride etc., and the limiting growth substrate is not transparent substrates or extinction substrate; With the organometallic chemistry vapour phase epitaxy method in regular turn growing n-type semiconductor layer 2 (as n-GaN, n-AlGaInP), multiple quantum well active layer 3 is (as InGaN, AlGaInP), p type semiconductor layer 4 is (as p-GaN, layer such as p-AlGaInP), to form light emitting diode epitaxial structure, wherein n type semiconductor layer, p type semiconductor layer can be used as limiting layer.Utilize the novel holography exposure system structure of Fig. 2 again, the twice incident light directly beaten formed interference fringe on light-emitting diode total surface, when selected laser source wavelength less than limiting layer 4 (p type semiconductor layer) corresponding wavelength (λ of institute
Laser＜λ
Cladding), incident light then can be limited layer (p type semiconductor layer) surface and absorb generation localized hyperthermia, produces quantum well diffusion inside effect by thermal diffusion.This twice incident light is interfered can reach the intensity variation that the cycle is 200nm-1000nm, and again by control luminous intensity and the length of incident light time, may command energy gap in various degree changes and the change of refractive amount.Utilize circulator (Rotator) B to determine the angle Ψ (can between the 20-90 degree) of twice quantum well diffusion inside effect more on demand, same by the control luminous intensity, it is poor than macro-energy that the zone (staggered place) of repetition quantum well diffusion inside effect is had, and then produce the change of refractive amount.This variable quantity has two-dimensional space periodically, and this two-dimentional cycle do not need unanimity, promptly form photonic crystal light-emitting element (as Fig. 6 b).On the p type semiconductor layer, form current spreading layer 7 again, by current spreading layer after be etched down to the n type semiconductor layer, on current spreading layer and n type semiconductor layer, form p type electrode 9 and n type electrode 8 respectively, promptly form the photonic crystal light-emitting diode element, as shown in Figure 8.
(embodiment three)
Shown in Fig. 6 a, at growth substrate 1, its material can be GaAs, silicon, carborundum, aluminium oxide, indium phosphide, gallium phosphide, aluminium nitride or gallium nitride etc., and the limiting growth substrate is not transparent substrates or extinction substrate; With the organometallic chemistry vapour phase epitaxy method in regular turn growing n-type semiconductor layer 2 (as n-GaN, n-AlGaInP), multiple quantum well active layer 3 is (as InGaN, AlGaInP), p type semiconductor layer 4 is (as p-GaN, layer such as p-AlGaInP), to form light emitting diode epitaxial structure, wherein n type semiconductor layer, p type semiconductor layer can be used as limiting layer.Utilize the novel holography exposure system structure of Fig. 2 again, the twice incident light directly beaten formed interference fringe on light-emitting diode total surface, when selected laser source wavelength less than 3 corresponding wavelength (λ of multiple quantum well active layer structure
Laser＜λ
QW), this twice incident light is interfered can reach the intensity variation that the cycle is 200nm-1000nm, and again by control luminous intensity and the length of incident light time, may command energy gap in various degree changes and the change of refractive amount.Utilize circulator (Rotator) B to determine the angle Ψ (can between the 20-90 degree) of twice quantum well diffusion inside effect more on demand, same by the control luminous intensity, it is poor than macro-energy that the zone (staggered place) of repetition quantum well diffusion inside effect is had, and then produce the change of refractive amount.This variable quantity has two-dimensional space periodically, and this two-dimentional cycle do not need unanimity, promptly form photonic crystal light-emitting element (as Fig. 6 b).On the p type semiconductor layer, form current spreading layer 7 again, by current spreading layer after be etched down to the n type semiconductor layer, on current spreading layer and n type semiconductor layer, form p type electrode 9 and n type electrode 8 respectively, promptly form the photonic crystal light-emitting diode element, as shown in Figure 8.
Though the present invention discloses as above with preferred embodiment; right its is not in order to limit the present invention; those skilled in the art without departing from the spirit and scope of the present invention, when can being used for a variety of modifications and variations, so protection scope of the present invention is when looking being as the criterion that accompanying Claim defines.
Claims (9)
1. light-emitting component comprises:
Substrate; And
The semiconductor epitaxial structure is positioned on this substrate, wherein this semiconductor epitaxial structure has mqw active layer, and this mqw active layer is included in one dimension or two-dimensional space has the periodically photon crystal structure of change in dielectric constant, and wherein this photon crystal structure is to interfere in this mqw active layer in conjunction with the twice incident light by the basis with the holography exposure technique to cause the diffusion inside effect to be formed.
2. light-emitting component as claimed in claim 1, wherein this semiconductor epitaxial structure also comprises:
The first electrical semiconductor layer is formed between this substrate and this mqw active layer; And
The second electrical semiconductor layer is formed on this mqw active layer, and this first electrical semiconductor layer and/or this second electrical semiconductor layer can be used as limiting layer.
3. light-emitting component as claimed in claim 1, wherein this change in dielectric constant has the one-dimensional space periodically, and its scope is 200nm-1000nm.
4. light-emitting component as claimed in claim 1, wherein this change in dielectric constant has two-dimensional space periodically, and its scope is 200nm-1000nm, and cycle that should two dimension does not need unanimity.
5. light-emitting component as claimed in claim 1, wherein the optical maser wavelength of this holography exposure technique needs less than light wavelength that this mqw active layer produces.
6. light-emitting component as claimed in claim 2, wherein this lambda1-wavelength is less than this first semiconductor layer and/or the pairing wavelength of this second semiconductor layer.
7. light-emitting component as claimed in claim 6, wherein this lambda1-wavelength is between this first semiconductor layer and/or this second semiconductor layer and the pairing wavelength of this quantum well.
8. light-emitting component as claimed in claim 1, wherein this photon crystal structure is interfered the secondary quantum well diffusion inside effect that causes through secondary twice incident light, and the angle of this secondary quantum well diffusion inside effect can form two-dimensional photon crystal structure between the 20-90 degree.
9. light-emitting component as claimed in claim 1, wherein this photon crystal structure has one dimension or the variation of the periodic material composition of two-dimensional space.
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| CN101916805A (en) * | 2010-07-13 | 2010-12-15 | 东南大学 | Concentric photonic crystal structure for improving outer luminous efficiency of light-emitting diode |
| TWI543386B (en) | 2011-03-28 | 2016-07-21 | 財團法人工業技術研究院 | Circular photonic crystal structure, light emitting diode device and photoelectric conversion device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1320972A (en) * | 2001-05-24 | 2001-11-07 | 北京大学 | Semiconductor LED and its preparing process |
| CN1874012A (en) * | 2005-06-03 | 2006-12-06 | 北京大学 | High-luminance chip of luminescent tube in GaN base, and preparation method |
| CN1877872A (en) * | 2005-06-09 | 2006-12-13 | 中国科学院半导体研究所 | Photonic crystal-structural GaN-base blue LED structure and method for fabricating same |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1320972A (en) * | 2001-05-24 | 2001-11-07 | 北京大学 | Semiconductor LED and its preparing process |
| CN1874012A (en) * | 2005-06-03 | 2006-12-06 | 北京大学 | High-luminance chip of luminescent tube in GaN base, and preparation method |
| CN1877872A (en) * | 2005-06-09 | 2006-12-13 | 中国科学院半导体研究所 | Photonic crystal-structural GaN-base blue LED structure and method for fabricating same |
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