CN103812004A - Laser diode with GaN substrate - Google Patents
Laser diode with GaN substrate Download PDFInfo
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- CN103812004A CN103812004A CN201210440780.2A CN201210440780A CN103812004A CN 103812004 A CN103812004 A CN 103812004A CN 201210440780 A CN201210440780 A CN 201210440780A CN 103812004 A CN103812004 A CN 103812004A
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- layer
- impurity
- laser diode
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Abstract
A laser diode with a GaN substrate comprises a buffer layer (11), a co-doping layer (12), an n-type coating layer, an active layer and a P-type coating layer, wherein the buffer layer (11) is arranged on the GaN substrate, the co-doping layer (12) is arranged on the buffer layer (11), the n-type coating layer is arranged on the co-doping layer (12), the active layer is arranged on the n-type coating layer and is composed of a nitride III-V group compound semiconductor, and the P-type coating layer is arranged on the active layer. The co-doping layer (12) is composed of a III-V group compound semiconductor which at least comprises gallium in 3B group elements and nitrogen in 5B group elements. The co-doping layer (12) is jointly doped with one of silicon and germanium serving as impurities of donors and one of magnesium and zinc serving as impurities of acceptors. The carrier concentration of the co-doping layer (12) is from 2.0*1018cm<-3> to 8.0*1018cm<-3>, the forbidden band of the co-doping layer is narrower than that of the n-type coating layer, and the conductive type of the co-doping layer is n-type. The laser provided by the invention is stable in light output wavelength and has higher luminous efficiency.
Description
Technical field
The present invention relates to a kind of semiconductor laser diode, relate in particular to a kind of laser tube of GaN substrate.
Background technology
In the fields such as optical fiber communication, Fibre Optical Sensor, medical detection, environmental monitoring, scientific research, semiconductor laser is widely used.In recent years, the nitride laser diode device of GaN substrate has been widely used as the technical fields such as high-capacity CD-ROM, Fibre Optical Sensor, environmental monitoring, optical communication, has the device of higher output and higher reliability in positive research and development.In such nitride laser diode device, realize by use photoconductive layer and coating with respect to the optics constraint in the vertical direction (vertical direction) of active layer.
Existing laser diode device exists many deficiencies and defect at aspects such as light output stability, luminous efficiencies.
Summary of the invention
For overcoming the shortcomings and deficiencies of prior art, the object of the present invention is to provide one to there is better light output stability, the GaN substrate laser diode that luminous efficiency is higher.For solving the problems of the technologies described above, the invention provides following technical scheme:
A kind of GaN substrate laser diode device, comprising:
Be arranged on the resilient coating (11) on GaN substrate;
Be arranged on the codoped layers (12) on resilient coating;
Be arranged at codoped layers 12 N-shaped coating layer above;
On N-shaped coating layer, be provided with active layer, formed by nitride III-V compound semiconductor;
On active layer, be provided with P type coating layer;
Described codoped layers, is made up of the III-V compound semiconductor that comprises gallium and nitrogen, and by codope as the silicon of the impurity of alms giver work with as the magnesium of the impurity of acceptor's work,
The carrier concentration of wherein said codoped layers is from 2.0 × 10
18cm
-3to 8.0 × 10
18cm
-3, and
Wherein said codoped layers has the forbidden band narrower than the forbidden band of described N-shaped coating, and the conduction type of described codoped layers is N-shaped.
Described N-shaped coating layer comprises the first N-shaped coating layer and the second N-shaped coating layer.
Wherein said N-shaped coating is by Al
xga
1-xn mixed crystal forms, wherein 0.01 < x≤0.86, research shows that the probability that semiconductor chip cracks increases greatly if the content of aluminium exceedes 0.86, and has for given aluminium composition ratio x the thickness that is no more than crackle generation critical film thickness degree.
In wherein said codoped layers, the concentration of Mg impurity is 2.6 × 10
18cm
-3to 5.3 × 10
18cm
-3, the concentration of Si impurity is 3.0 × 10
18cm
-3to 6.0 × 10
18cm
-3.
Be wherein 50-200nm as the thickness of described codoped layers.
From following description, of the present invention other and further target, feature and advantage will be obvious more fully.
Accompanying drawing explanation
Fig. 1 is the sectional view illustrating according to the structure of the laser diode device of the embodiment of the present invention;
Embodiment
Below with reference to accompanying drawing, embodiments of the invention are described.
Fig. 1 shows according to the cross section structure of the laser diode device of the embodiment of the present invention, this laser diode has wherein codoped layers 13, the first N-shaped coating 14, the second N-shaped coating 15, N-shaped photoconductive layer 16, n side interlayer 17, active layer 18, p side interlayer 19, electronic barrier layer 20, p-type coating 21 and p side contact layer 22 and is laminated in successively in a face side of the substrate 11 being made up of GaN, has resilient coating 12 and is positioned at middle.
For example 1.00-5.00 μ m is thick for resilient coating 12, and is made up of as the N-shaped GaN of the silicon Si of N-shaped impurity doping.
Codoped layers 13 is for absorbing the light that oozes out into substrate 11 sides by the second N-shaped coating 15 and the first N-shaped coating 14.Codoped layers 13 is set to adjacent to the first N-shaped coating 14, and has the narrow forbidden band, forbidden band than the first N-shaped coating 14 and the second N-shaped coating 15.Codoped layers 13 by for example comprise gallium Ga in 3B family element at least and at least the nitride III-V compound semiconductor of the nitrogen N in 5B family element form, and be doped as the silicon Si of the impurity of alms giver's work with as the magnesium Mg of the impurity of acceptor's work.Thus, in this laser diode device, can suppress to ooze out into the light of substrate 11 sides and the Mode Coupling through the light of the waveguide of active layer 18.
The example of the component materials of codoped layers 13 comprises GaN and InGaN mixed crystal.Particularly, preferred GaN.Using in the situation of InGaN mixed crystal, although can increase absorption coefficient, restive optimal composition, and existence affects the possibility of the crystallization of the first N-shaped coating 14.
Research shows, the not Doped GaN layer of impurity is not no more than 10 at the absorption coefficient (cm-1) at 400nm place, the GaN layer of doped silicon Si can not exceed 30 at the absorption coefficient (cm-1) at 400nm place,, magnesium-doped Mg GaN layer can not exceed 100 at the absorption coefficient (cm-1) at 400nm place, and and the GaN layer absorption coefficient of codope silicon Si and magnesium Mg apparently higher than single other sample of planting impurity of doping.Research is simultaneously 2.6 × 10 containing the concentration of finding Mg impurity
18cm
-3to 5.3 × 10
18cm
-3, the concentration of Si impurity is 3.0 × 10
18cm
-3to 6.0 × 10
18cm
-3there is peak value in Shi Shangshu absorption coefficient, can reach 1000, and this numerical value is applicable to the stable laser of laser output wavelength the most, and is outward that luminous efficiency obviously declines in above-mentioned concentration range.
Find to be arranged in the situation between substrate 11/ resilient coating 12 and the first N-shaped coating 14 at codoped layers 13, the light that oozes out into substrate 11 sides by the second N-shaped coating 15 and the first N-shaped coating 14 can be absorbed and not increase the thickness of the first N-shaped coating 14 and the second N-shaped coating 15.In addition, can avoid absorbing amount excessive by adjusting the thickness of codoped layers 13 and the interpolation concentration of impurity.Thereby, can avoid threshold current or operating current to increase.But the thickness of codoped layers 13 is preferably 480nm or less.If the thickness of codoped layers 13 is 480nm or larger, crystallinity may be disturbed by codope.
Preferably N-shaped of the conduction type of codoped layers 13.The carrier concentration of codoped layers 13 is preferably from 2.0 × 10
18cm
-3to 8.0 × 10
18cm
-3, all comprise two-end-point.2.0 × 10
18cm
-3carrier concentration realize the distribute lower limit of (inverted population) necessary charge carrier of reversion corresponding to producing.Value 8.0 × 10
19cm
-3corresponding to be doped the higher limit that can produce carrier concentration in the situation of impurity in crystallization and the impregnable scope of optical characteristics at codoped layers 13.
The interpolation concentration of the impurity (for example magnesium Mg) as acceptor's work of codoped layers 13, preferably from 2.6 × 10
18cm
-3to 5.3 × 10
18cm
-3.Research shows in above-mentioned number range the most favourable to producing charge carrier.If the interpolation concentration of magnesium Mg exceeds above-mentioned number range, carrier concentration becomes gradually and reduces.In the time that certain impurity adds concentration, carrier concentration phenomenon saturated or that decline also appears in other compound semiconductor.In addition, occur if impurity is added carrier concentration saturated or decline time, degree of crystallinity decline.Thereby, as the higher limit of the interpolation concentration of the impurity of the acceptor work of codoped layers 13 preferably 5.3 × 10
18cm
-3.Adjust interpolation concentration and make to obtain desirable uptake the scope from lower limit to higher limit.Particularly, about 5.0 × 10
18cm
-3can be implemented.
The interpolation concentration of the impurity of working as the acceptor of codoped layers 13 can be uniformly in the thickness direction of codoped layers 13, but adding concentration can increase gradually, or can reduce gradually.For example, as the interpolation concentration of the impurity of acceptor work at the two ends of the thickness direction of codoped layers 13 (with the near interface of substrate 11 or with the near interface of the first N-shaped coating 14) preferred interpolation concentration as the impurity of acceptor's work lower than the thickness direction Zhong center at codoped layers 13 all.Thus, avoid for example, being dispersed in substrate 11 or in the first N-shaped coating 14 as the impurity (magnesium) of acceptor's work.
The interpolation concentration of the impurity (for example silicon Si) of working as the alms giver of codoped layers 13, preferably the concentration of Si impurity is 3.0 × 10
18cm
-3to 6.0 × 10
18cm
-3.The impurity (for example silicon Si) as alms giver's work that shows N-shaped conductivity, must be added into codoped layers 13.The interpolation concentration of silicon Si by with as be subject to main quilt codope impurity (for example magnesium Mg) interpolation concentration relation and determined.Should be added the carrier concentration of codoped layers 13 is become from 2.0 × 10 as the impurity of alms giver's work
18cm
-3to 8.0 × 10
18cm
-3, in above-mentioned scope time, laser diode luminous efficiency is the highest.The interpolation concentration of the impurity of working as alms giver particularly, can be about 5.0 × 10
18cm
-3.
Preferably at the first N-shaped coating 14 shown in Fig. 1 and the second N-shaped coating 15 respectively by for example, there is the Al of mutually different compositions
xga
1-xn (0 < x≤0.86) mixed crystal forms, and has the thickness that is no more than the critical film thickness degree cracking for given aluminium composition ratio x.Thus, can result from the first N-shaped coating 14 and the second N-shaped coating 15 by Crack prevention, and can improve productive rate by shortening growth time.In addition the advantage that, exists serial resistance to be lowered by reducing the thickness of the first N-shaped coating 14 and the second N-shaped coating 15.
Aluminium composition ratio x's is 0.045 ideally, and thickness t is from 2.5 μ m to 2.6 μ m ideally, all comprises two-end-point.
Particularly, for example 2.40 μ m are thick for the first N-shaped coating 14, and by doped silicon Si the N-shaped Al as N-shaped impurity
0.03ga
0.97n mixed crystal forms.For example 0.20 μ m is thick for the second N-shaped coating 15, and by doped silicon Si the N-shaped Al as N-shaped impurity
0.01ga
0.99n mixed crystal forms.The aluminium composition ratio of the first N-shaped coating 14 is different from the aluminium composition ratio of the second N-shaped coating 15, to avoid because the peak of the luminous intensity producing in active layer 18 reduces characteristic to the first N-shaped coating 14 side displacements.
At the N-shaped photoconductive layer 16 shown in Fig. 1, for example 0.21 μ m is thick, and is made up of as the N-shaped GaN of N-shaped impurity doped silicon Si.For example 0.005 μ m is thick for n side interlayer 17 shown in Figure 1, and is made up of the not doping GaInN mixed crystal of impurity not.
For example 0.056 μ m is thick for active layer 18 shown in Figure 1, and has by the Ga with mutual different components
xin
1-xthe multi-quantum pit structure that the trap layer that N (x>=0) mixed crystal forms respectively and base layer form.
For example 0.027 μ m is thick for p side interlayer 19 shown in Figure 1, and is made up of the not doping GaInN mixed crystal of impurity not.At the electronic barrier layer 20 shown in Fig. 1, for example 0.02 μ m is thick, and is made up of as the p-type AlGaN mixed crystal of p-type impurity magnesium-doped Mg.At the p-type coating 21 shown in Fig. 1, for example 0.38 μ m is thick, and has the superlattice structure being made up of as p-type AlGaN mixed crystal layer and the p-type GaN layer of p-type impurity magnesium-doped Mg.For example 0.10 μ m is thick for p side contact layer 22 shown in Figure 1, and is made up of as the p-type GaN of p-type impurity magnesium-doped Mg.
In the p side contact layer 22 shown in Fig. 1, p lateral electrode 31 use have by SiO
2the buried layer 23 of the stepped construction that layer and Si layer betwixt form forms.P lateral electrode 31 for example has wherein palladium (Pd), platinum (Pt) and gold (Au) in order from the stacked structure of p side contact layer 22 sides, and is electrically connected to p side contact layer 22.P lateral electrode 31 is extended for restriction of current with strip.Active layer 18 is luminous zones corresponding to the region of p lateral electrode 31.Meanwhile, substrate 11 below on, form n lateral electrode 32.N lateral electrode 32 for example has titanium (Ti) wherein, platinum (Pt) and gold (Au) stacked structure in order.N lateral electrode 32 is electrically connected to the first N-shaped coating 14, is and substrate 11, resilient coating 12 and codoped layers 13 between the two.
In laser diode device, for example, are a pair of end faces of oscillator in the longitudinal opposed facing a pair of side of p lateral electrode 31.On a pair of end face of oscillator, form respectively a pair of mirror coating (not being illustrated).In this pair of mirror coating, a mirror coating is adjusted to have lower reflection coefficient, and another mirror coating is adjusted to have higher reflection coefficient.Thus, the light producing in active layer 18 comes and goes, is exaggerated and penetrated from a described mirror coating as laser beam between this pair of mirror coating.
Laser diode can be for example manufactured as follows.
First the substrate 11 that, preparation is made up of GaN.On the surface of substrate 11, for example, by MOCVD (metal organic chemical vapor deposition) the method resilient coating 12 of being made by previous materials of growing.
Then, again by the mocvd method codoped layers of growing.Now, provide gallium raw gas and nitrogen raw gas, silicon material gas and magnesium raw gas are provided, and the impurity that codope silicon is worked as acceptor as impurity and the magnesium of alms giver's work thus, codoped layers 13 formed.
Subsequently, again by mocvd method grow the first N-shaped coating 14, the second N-shaped coating 15, N-shaped ducting layer 16, n side interlayer 17, active layer 18, p side interlayer 19, electronic barrier layer 20, p-type coating 21 and the p side contact layer 22 made by previous materials.
Carrying out in MOCVD, for example trimethyl gallium (CH
3)
3ga is as gallium raw gas, for example trimethyl aluminium (CH
3)
3al is as aluminium raw gas, for example trimethyl indium (CH
3)
3in is as indium raw gas, and for example ammonia NH
3used respectively as nitrogen raw gas.In addition for example silane SiH,
4as silicon material gas, and for example two luxuriant magnesium (bis (cyclopentadienyl) magnesium, (C
5h
5) 2Mg) be used as magnesium raw gas.
Then, mask (not shown) is formed in p side contact layer 22.By using this mask, p side contact layer 22 and part p-type coating 21 are selectively etched by for example RIE (reactive ion etching) method, to the top of p-type coating 21 and p side contact layer 22 are formed as to bar shaped projection striped portion.
As a result, on p-type coating 21 and p example contact layer 22, form the buried layer 23 of being made by previous materials.In buried layer 23, provide corresponding to the opening of p side contact layer 22 to form p lateral electrode 31.In addition, the side below of substrate 11 is for example polished or polishing makes the thickness of substrate 11 become for example about 100 μ m.After this, n lateral electrode 32 be formed at substrate 11 below on.After this, substrate 11 is formed given size, and mirror coating (not shown) is formed on a pair of relative oscillator end face.Thereby, complete laser diode device shown in Figure 1.
In laser diode, be applied in the situation between n side diode 32 and p side diode 31 at given voltage, electric current is injected into active layer 18, and light penetrates by electron-hole is compound.This light is reflected by a pair of mirror coating, comes and goes betwixt, produces laser generation, and is transmitted to outside as laser beam.In this embodiment, the codoped layers 13 being made up of as the silicon Si mono-of the impurity of alms giver work with as the GaN of the magnesium Mg of the impurity of acceptor's work doping is arranged between substrate 11/ resilient coating 12 and the first N-shaped coating 14.Thereby the light that oozes out into substrate 11 by the second N-shaped coating 15 and the first N-shaped coating 14 is absorbed in codoped layers 13, and be attenuated to not can with the degree of the generation Mode Coupling of the light of the waveguide by active layer 18.Thereby, in FFP, do not observe ripple, and allow stable laser generation.
In addition, for example, in the aforementioned embodiment, the structure of laser diode device is described with instantiation.But, all layers are not necessarily provided, or other layer can be further provided.
Be apparent, however, to one skilled in the art that according to designing requirement and other factors can there are various improvement, combination, from combination with substitute, as long as they are in the scope of claim and equivalent thereof.
Claims (5)
1. a GaN substrate laser diode device, comprising:
Be arranged on the resilient coating on GaN substrate;
Be arranged on the codoped layers on resilient coating;
Be arranged at the N-shaped coating layer above codoped layers;
On N-shaped coating layer, be provided with active layer, formed by nitride III-V compound semiconductor;
On active layer, be provided with P type coating layer;
Described codoped layers, is made up of the III-V compound semiconductor that comprises gallium and nitrogen, and by codope as the silicon of the impurity of alms giver work with as the magnesium of the impurity of acceptor's work,
The carrier concentration of wherein said codoped layers is from 2.0 × 10
18cm
-3to 8.0 × 10
18cm
-3, and
Wherein said codoped layers has the forbidden band narrower than the forbidden band of described N-shaped coating, and the conduction type of described codoped layers is N-shaped.
2. according to the laser diode device of claim 1, described N-shaped coating layer comprises the first N-shaped coating layer and the second N-shaped coating layer.
3. according to the laser diode device of claim 1, wherein said N-shaped coating is by Al
xga
1-xn mixed crystal forms, wherein 0.01 < x≤0.86, and there is the thickness that is no more than crackle generation critical film thickness degree for given aluminium composition ratio x.
4. according to the laser diode device of claim 1, in wherein said codoped layers, the concentration of Mg impurity is 2.6 × 10
18cm
-3to 5.3 × 10
18cm
-3, the concentration of Si impurity is 3.0 × 10
18cm
-3to 6.0 × 10
18cm
-3.
5. according to the laser diode device of claim 1, be wherein 50-200nm as the thickness of described codoped layers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210440780.2A CN103812004A (en) | 2012-11-07 | 2012-11-07 | Laser diode with GaN substrate |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210440780.2A CN103812004A (en) | 2012-11-07 | 2012-11-07 | Laser diode with GaN substrate |
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| Publication Number | Publication Date |
|---|---|
| CN103812004A true CN103812004A (en) | 2014-05-21 |
Family
ID=50708398
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|---|---|---|---|
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106684218A (en) * | 2017-03-01 | 2017-05-17 | 湘能华磊光电股份有限公司 | LED epitaxial growth method capable of improving light-emitting efficiency |
| CN109698466A (en) * | 2017-10-24 | 2019-04-30 | 夏普株式会社 | Semiconductor Laser device |
| CN110132322A (en) * | 2019-04-08 | 2019-08-16 | 东莞理工学院 | A kind of ultraviolet irradiation enhanced fiber sensor and preparation method thereof |
-
2012
- 2012-11-07 CN CN201210440780.2A patent/CN103812004A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106684218A (en) * | 2017-03-01 | 2017-05-17 | 湘能华磊光电股份有限公司 | LED epitaxial growth method capable of improving light-emitting efficiency |
| CN109698466A (en) * | 2017-10-24 | 2019-04-30 | 夏普株式会社 | Semiconductor Laser device |
| CN110132322A (en) * | 2019-04-08 | 2019-08-16 | 东莞理工学院 | A kind of ultraviolet irradiation enhanced fiber sensor and preparation method thereof |
| CN110132322B (en) * | 2019-04-08 | 2021-01-22 | 东莞理工学院 | Ultraviolet radiation enhanced optical fiber sensor and preparation method thereof |
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Application publication date: 20140521 |