CN1773792A - Semiconductor light-emitting device - Google Patents
Semiconductor light-emitting device Download PDFInfo
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- CN1773792A CN1773792A CNA2005101194895A CN200510119489A CN1773792A CN 1773792 A CN1773792 A CN 1773792A CN A2005101194895 A CNA2005101194895 A CN A2005101194895A CN 200510119489 A CN200510119489 A CN 200510119489A CN 1773792 A CN1773792 A CN 1773792A
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Abstract
The present invention provides a semiconductor light-emitting device which exhibits small threshold current, high differential efficiency and good characteristics, by reducing electrons that overflow an electron barrier for trapping the electrons in an active layer. Of barrier layers that configure an active layer 20 , a final barrier layer 1 , which is a barrier layer closest to a p side, is made smaller in band gap than a barrier layer 2 . Thus, as compared with a case where the barrier layer 1 is made of a material having the same band gap as that of the barrier layer 2 , a band discontinuous amount (electron barrier) with an electron blocking layer 3 can be made larger. As a result, it is possible to reduce electrons that overflow the electron barrier.
Description
Technical field
The present invention relates to use the semiconductor light-emitting elements of nitride series III-V compound semiconductor.
Background technology
In recent years, as at necessary semiconductor laser that can be luminous from the blue region to the ultraviolet range aspect the densification of CD, use the research and development of nitride series semiconductor laser of the nitride series III-V compound semiconductor of AlGaInN etc. carrying out actively, realized practicability.
In the nitride series semiconductor laser of having reported up to now, as its active layer structure, mostly use alternately stacked by trap layer that constitutes more than or equal to 2 layers InGaN and multiple quantum trap structure by the barrier layer that constitutes more than or equal to 3 layers the InGaN that compares In ratio of components little (usually about 0.02) with above-mentioned trap layer.
At this, in nitride series III-V compound semiconductor, conduction band when having formed heterojunction can be about 2.5: 7.5 with the ratio that can be with discontinuous quantity of discontinuous quantity and valence band, conduction band can be with discontinuous quantity very little (with reference to Applied Physics LetterVol.70 (1997) p.2577) as can be known.Therefore, electronics is crossed the barrier layer and is overflowed from the trap layer easily, and the deterioration of the rising of threshold current, differential efficiency and temperature characterisitic becomes problem easily.
Therefore, in order to address this problem, the band gap that can consider to increase as far as possible the barrier layer can be with the method for discontinuous quantity with what increase conduction band.Wherein, preferably use the as far as possible little InGaN of In ratio of components to compare the big material of band gap (material) with InGaN as barrier layer or use GaN, AlGaN, InAlGaN etc.
If increase the band gap on barrier layer, then the discontinuous quantity of being with of valence band increases.But, if use the as far as possible little InGaN of In ratio of components, then because the band gap of these materials is big more, lattice constant is just more little, so be subjected to bigger stretcher strain as barrier layer or use GaN, AlGaN.And, according to the semi-conductive physical property that can band of being out of shape, can not take place conduction band can be with discontinuous quantity be big more valence band can be with the also big more situation of discontinuous quantity.
Its result can not think to cause that the hole is difficult to be injected into equably the problem more than or equal in 2 layers the trap, can solve the problem of overflowing of electronics.
Have again, in patent documentation 1, disclose the prior art related with the present invention.
[patent documentation 1] spy opens flat 7-170022 communique
But, the inventor with simplation validation at the material that will have big band gap as electronics overflows such new problem easily from crossing electron barrier layer as the final barrier layer of approaching p side barrier layer most situation takes place under the situation on barrier layer.Can think that this problem is because the material by will big band gap is used as the barrier layer makes and can reduce to produce with discontinuous quantity (electronic barrier) between final barrier layer and the electron barrier layer.
Moreover, even compare the barrier layer of the little InGaN of band gap with GaN, AlGaN, the ratio of the electronics of crossing electronic barrier from final barrier layer and overflowing neither 0, becomes the main cause that threshold current, differential efficiency and the temperature characterisitic etc. that make semiconductor light-emitting elements worsen.
Therefore, can consider following method: omit final barrier layer,, compare, improved electronic barrier, reduced the electronics that overflows with the situation that final barrier layer is arranged by direct joint trap layer and electron barrier layer.
But the film-forming temperature of electron barrier layer is compared with the film-forming temperature of trap layer, and is high about 200 ℃.Therefore, if desire plans directly to form electron barrier layer on the trap layer, then must form and make the film-forming temperature rising under original state of back on the surface of not protecting the trap layer at the trap layer.And, the situation that the known crystallinity that trap laminar surface portion betwixt arranged worsens.
If the trap layer that uses such crystallinity to worsen makes semiconductor light-emitting elements, then be closed in electronics in this trap layer just to not contribution of laser vibration, produce the problem of the deterioration that causes threshold current or differential efficiency.
Summary of the invention
Therefore, the objective of the invention is to cross the electronics that electronic barrier that active layer inner sealing electronics uses overflows by minimizing the semiconductor light-emitting elements that possesses the good characteristic that threshold current is little, differential efficiency is high is provided by providing.
The 1st aspect of the present invention is a kind of semiconductor light-emitting elements that has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that: above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms, and the band gap on final barrier layer that approaches above-mentioned p type covering one side in above-mentioned a plurality of barrier layers most is littler than the band gap on the barrier layer beyond the above-mentioned final barrier layer.
The 7th aspect of the present invention is a kind of semiconductor light-emitting elements that has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that: above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms, above-mentioned a plurality of barrier layer comprises the final barrier layer of approaching above-mentioned p type covering one side most, above-mentioned final barrier layer comprises the 1st final barrier layer that is configured in said n type covering one side and the 2nd final barrier layer that is configured in above-mentioned p type covering one side, and the band gap on the above-mentioned the 2nd final barrier layer is littler than the band gap on the barrier layer beyond the above-mentioned final barrier layer.
The 9th aspect of the present invention is a kind of semiconductor light-emitting elements that has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that: above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms, above-mentioned a plurality of barrier layer comprises the final barrier layer of approaching above-mentioned p type covering one side most, the material on above-mentioned final barrier layer is InGaN, and the material on the barrier layer beyond the above-mentioned final barrier layer is GaN.
The 10th aspect of the present invention is a kind of semiconductor light-emitting elements that has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that: above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms, the final barrier layer of approaching above-mentioned p type covering one side in above-mentioned a plurality of barrier layer most comprises the final barrier layer of a plurality of parts, and the band gap on the final barrier layer of part 1 that approaches above-mentioned p type covering one side in the final barrier layer of above-mentioned a plurality of parts most is than little with the band gap on the final barrier layer of part of the final barrier layer of above-mentioned part 1 adjacency.
The 12nd aspect of the present invention is a kind of semiconductor light-emitting elements that has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that: above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms, the final barrier layer of approaching above-mentioned p type covering one side in above-mentioned a plurality of barrier layer most comprises the final barrier layer of a plurality of parts, the material that approaches most the final barrier layer of part 1 of above-mentioned p type covering one side in the final barrier layer of above-mentioned a plurality of part is InGaN, with the material on the final barrier layer of part of the final barrier layer of above-mentioned part 1 adjacency be band gap InGaN or the GaN bigger than the band gap on the final barrier layer of above-mentioned part 1.
The 13rd aspect of the present invention is a kind of semiconductor light-emitting elements that has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that: above-mentioned active layer have a plurality of barrier layers and with the trap layer that above-mentioned barrier layer alternately is formed, possess: the barrier layer that its band gap is bigger than the band gap on above-mentioned a plurality of barrier layers; And the 1st layer, being provided between above-mentioned a plurality of barrier layer and the above-mentioned barrier layer and joining with above-mentioned barrier layer, its band gap is littler and its band gap is bigger than the band gap of above-mentioned trap layer than the band gap on above-mentioned a plurality of barrier layers.
The 14th aspect of the present invention is a kind of semiconductor light-emitting elements that has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that: the trap layer that above-mentioned active layer has a plurality of barrier layers and alternately is formed with above-mentioned barrier layer, possess: optical waveguide layer, its band gap is bigger than the band gap on above-mentioned a plurality of barrier layers, joins with above-mentioned active layer one side of above-mentioned p type covering and is set up; And the 1st layer, being provided between above-mentioned a plurality of barrier layer and the above-mentioned optical waveguide layer and joining with above-mentioned optical waveguide layer, its band gap is littler and its band gap is bigger than the band gap of above-mentioned trap layer than the band gap on above-mentioned a plurality of barrier layers.
The 15th aspect of the present invention is a kind of semiconductor light-emitting elements that has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that: the trap layer that above-mentioned active layer has a plurality of barrier layers and alternately is formed with above-mentioned barrier layer, possess the 1st layer, the 1st layer is provided between above-mentioned a plurality of barrier layer and the above-mentioned p type covering and joins with above-mentioned p type covering, and its band gap is littler and its band gap is bigger than the band gap of above-mentioned trap layer than the band gap on above-mentioned a plurality of barrier layers.
According to the 1st aspect of the present invention, make the band gap on final barrier layer littler than the band gap on the barrier layer beyond the final barrier layer.Therefore, for example compare as the situation on final barrier layer with having used the barrier layer beyond the final barrier layer, can increase and p type covering between the electronic barrier that forms.Its result can reduce from active layer and cross electronic barrier and the electronics that overflows.
In addition, owing on the trap layer, formed final barrier layer, there is not the crystallinity of trap layer to worsen such problem yet.
According to the 7th aspect of the present invention, make the band gap on the 2nd final barrier layer littler than the band gap on the barrier layer beyond the final barrier layer.Therefore, for example compare as the situation on final barrier layer with having used the barrier layer beyond the final barrier layer, can increase and p type covering between the electronic barrier that forms.Its result can reduce from active layer and cross electronic barrier and the electronics that overflows.
According to the 9th aspect of the present invention, make the band gap on final barrier layer littler than the band gap on the barrier layer beyond the final barrier layer.Therefore, for example compare as the situation on final barrier layer with having used the barrier layer beyond the final barrier layer, can increase and p type covering between the electronic barrier that forms.Its result can reduce from active layer and cross electronic barrier and the electronics that overflows.
According to the 10th aspect of the present invention, can increase the electronic barrier that between final barrier layer of part 1 and p type covering, forms.Its result can reduce from active layer and cross electronic barrier and the electronics that overflows.
According to the 12nd aspect of the present invention, can increase the electronic barrier that between final barrier layer of part 1 and p type covering, forms.Its result can reduce from active layer and cross electronic barrier and the electronics that overflows.
According to the 13rd aspect of the present invention, can increase the electronic barrier that between the 1st layer and barrier layer, forms.Its result can reduce from active layer and cross electronic barrier and the electronics that overflows.
According to the 14th aspect of the present invention, can increase the electronic barrier that between the 1st layer and optical waveguide layer, forms.Its result can reduce from active layer and cross electronic barrier and the electronics that overflows.
According to the 15th aspect of the present invention, can increase the electronic barrier that between the 1st layer and p type covering, forms.Its result can reduce from active layer and cross electronic barrier and the electronics that overflows.
Description of drawings
Fig. 1 is the profile that the structure of the nitride series semiconductor laser relevant with execution mode 1 is shown.
Fig. 2 is the profile of structure that the part active layer of the nitride series semiconductor laser relevant with execution mode 1 is shown.
Fig. 3 is the energy band diagram of the nitride series semiconductor laser relevant with execution mode 1.
Fig. 4 is the profile that is illustrated in the structure of the semiconductor light-emitting elements that uses in the simulation relevant with execution mode 1.
Fig. 5 is the figure that the analog result of the light output-current characteristics in the nitride series semiconductor laser relevant with execution mode 1 is shown.
Fig. 6 is that the electronics that illustrates in the nitride series semiconductor laser relevant with execution mode 1 overflows the figure of the analog result of ratio.
Fig. 7 is the energy band diagram of the nitride series semiconductor laser relevant with execution mode 2.
Fig. 8 is the energy band diagram of the nitride series semiconductor laser relevant with execution mode 3.
Symbol description
1 final barrier layer, 4GaN substrate, 6n type AlGaN covering, 8 part active layers, 10p type AlGaN covering, 12 ridges, 16p type electrode, 17n type electrode, 20 active layers
Embodiment
＜execution mode 1 〉
Fig. 1 is the profile that the structure of the nitride series semiconductor laser (semiconductor light-emitting elements) relevant with present embodiment is shown.This nitride series semiconductor laser has ridge-like structure and SCH structure.
As shown in fig. 1, the nitride relevant with present embodiment series semiconductor laser has formed n type GaN resilient coating 5 on the Ga face as an interarea of GaN substrate 4.This layer for reduce surface on the GaN substrate 4 concavo-convex, as far as possible flatly stacked its upper strata forms.
Then, n type AlGaN covering (n type covering) 6, n type GaN light guide layer 7, active layer 20, p type AlGaN electron barrier layer 3 (electron barrier layer, barrier layer) and on n type GaN resilient coating 5, have been stacked gradually as p type GaN light guide layer 9, p type AlGaN covering (p type covering) 10 and the p type GaN contact layer (p type contact layer) 11 of the side directed layer of p as the side directed layer of n.
At this, be chosen to the band gap of p type GaN light guide layer 9 bigger than the band gap on final barrier layer 1 described later and barrier layer 2.In addition, with active layer 20 1 sides of p type covering 10 mutually ground connection be provided with p type GaN light guide layer 9.
The thickness of n type GaN resilient coating 5 for example is 1 μ m, has for example mixed silicon (Si) as n type impurity.The thickness of n type AlGaN covering 6 for example is 1 μ m, has for example mixed Si as n type impurity, Al proportion of composing in this way 0.07.
Fig. 2 shows the profile of the part active layer 8 that constitutes active layer 20.For part active layer 8, alternately stacked by In
xGa
1-xThe barrier layer that N (x=0.02) constitutes (barrier layer beyond the final barrier layer 1) 2 and by In
yGa
1-yThe trap layer 18 that N (y=0.14) constitutes.And for example the thickness with barrier layer 2 forms 7nm, and for example the thickness with trap layer 18 forms 3.5nm.
Utilize the non-doping In of thickness for 20nm
zGa
1-zN has formed final barrier layer 1.In ratio of components z for example is 0.04.Because the In ratio of components z on final barrier layer 1 is bigger than the In ratio of components x (x=0.02) on other barrier layer 2, so compare with the band gap on barrier layer 2, becomes little band gap.
According to the above, In ratio of components x, y, z have satisfied 0＜x＜z＜y＜1.In addition, In ratio of components x, y, z have also satisfied (y-z)＞(z-x).
Moreover the thickness on final barrier layer 1 is different with the thickness of barrier layer 2, trap layer 18, and it is thicker to be selected to thickness.
Have, in the example of present embodiment, the trap number of active layer 20 is 3 again.
The thickness of p type AlGaN electron barrier layer 3 for example is 10nm, with the Al proportion of composing as forming 0.18.In addition, the thickness of p type GaN light guide layer 9 for example is 100nm.And the thickness of p type AlGaN covering 10 for example is 400nm, has for example mixed Mg as p type impurity, Al proportion of composing in this way 0.07.The thickness of p type GaN contact layer 11 for example is 100nm, has for example mixed Mg as p type impurity.
On p type AlGaN covering 10 and p type GaN contact layer 11 for example towards＜1-100 direction utilizes etching to form ridge 12.The width of ridge 12 for example is 2.2 μ m.
At this, on the GaN substrate 4 with the height dislocation zone that is in a few μ m～tens μ m width that formed with strip between the corresponding position of low defect region on formed ridge 12.And, for the side surface part of carrying out ridge 12 or the surface protection and the electric insulation of horizontal bottom surface sections, for example with the SiO of thickness 200nm
2The such dielectric film 14 of film forms and covers ridge 12.
Be provided with opening 15 on the part that in dielectric film 14, forms on ridge 12 tops.And, utilize opening 15 to seek electrically contacting of p type electrode 16 and p type contact layer 11.
Fig. 3 is near the energy band diagram the active layer 20 of the nitride relevant with present embodiment series semiconductor laser.In the energy band diagram shown in Figure 3, for the corresponding position of the structure of the nitride relevant series semiconductor laser with present embodiment attached with its structure be identical symbol.As can be seen from Figure 3, between final barrier layer 1 and the electron barrier layer 3 can be with discontinuous quantity than being with discontinuous quantity big between barrier layer 2 and the electron barrier layer 3.
In Fig. 3, barrier layer the 1, the 2nd, with trap layer 18 in abutting connection with and its band gap layer bigger than the band gap of trap layer 18, final barrier layer 1 is to join with trap layer 18 and its band gap is present in the layer that approaches the p side most in than the big layer of the band gap of trap layer 18.In present embodiment 1, make the band gap on this final barrier layer 1 littler than the band gap on the barrier layer 2 beyond the final barrier layer 1.This final barrier layer 1, such shown in Fig. 7 of execution mode 2 as described later, a plurality of layers 13,19 that also available its band gap is bigger than the band gap of trap layer 18 constitute.
In Fig. 3, as final barrier layer 1, between trap layer 18 that approaches most the p side and barrier layer 3, be provided with its band gap layer bigger than the band gap of the trap layer 18 that approaches the p side most, itself and the trap layer 18 and the barrier layer 3 that approach the p side are most joined, and the band gap on this final barrier layer 1 is littler than the band gap on the barrier layer 2 beyond the final barrier layer 1.
Have again, under the situation that barrier layer 3 is not set, also can between trap layer 18 that approaches most the p side and optical waveguide layer, be provided with its band gap than the band gap of trap layer 18 big the and final barrier layer littler than the band gap on barrier layer 2, under the situation that barrier layer 3 and optical waveguide layer are not set, also can between trap layer 18 that approaches most the p side and covering 10, be provided with its band gap than the band gap of trap layer 18 big the and final barrier layer littler than the band gap on barrier layer 2.
Secondly, the manufacture method of the semiconductor light-emitting elements relevant with present embodiment is described.
At first, on the GaN substrate 4 that utilizes heat to clean etc. in advance the surface has been carried out cleaning, utilize organometallic chemistry vapor phase growth (MOCVD) method, for example growing n-type GaN resilient coating 5 under 1000 ℃ growth temperature.
, utilize identical mocvd method, stack gradually n type AlGaN covering 6, n type GaN light guide layer 7, possess the In of non-doping thereafter
xGa
1-xN/In
yGa
1-yThe part active layer 8 of N multiple quantum trap structure, final barrier layer 1, p type AlGaN electron barrier layer 3 and the p type GaN light guide layer 9, p type AlGaN covering 10 and the p type GaN contact layer 11 that constitute by non-doping InGaN.
At this, growth temperature about these layers, for example the growth temperature with n type AlGaN covering 6 and n type GaN light guide layer 7 is decided to be 1000 ℃, growth temperature from part active layer 8 to the final barrier layer 1 of non-doping InGaN is decided to be 740 ℃, will be decided to be 1000 ℃ from the growth temperature of p type AlGaN electron barrier layer 3 to p type GaN contact layers 11.
On whole of wafer that above crystalline growth is through with, apply resist, utilize the resist figure (not shown) of the photoetching formation reservation shape corresponding with the shape of ridge 12.As mask, for example utilize RIE (reactive ion etching) method to carry out etching in the layer of p type AlGaN covering 10 in this resist figure.The ridge 12 that utilizes this etching to make to become the optical guided wave structure.In addition, as the etching gas of RIE, for example use the gas of chlorine system.
Secondly, under the original state that has stayed the resist figure that uses as mask, thickness is the SiO of 0.2 μ m to utilize CVD method, vacuum vapour deposition or sputtering method etc. for example to form on whole of substrate once more
2Film 14.Then, carry out in the removing of resist figure, removing the SiO that is on the ridge 12
2So-called the peeling off (lift-off) of film.Thus, form and to open 15 on the ridge 12.
Secondly, on whole of substrate, for example utilize vacuum vapour deposition to form Pt and Au film successively.Then, utilize the photoetching after resist applies, be formed for forming the resist figure of p type electrode 16.Then, as mask, utilize wet etching or dry etching to form p type electrode 16 in the resist figure.
On the back side front of substrate utilize vacuum vapour deposition successively form Ti and Al film thereafter.Then, the alloy treatment that n type electrode 17 ohmic contact are used.
Then, this substrate is processed as strip, forms two resonator end faces, and then after these resonator end faces have been carried out end face covering (coating), make this become chip by riving etc. by riving etc.Utilize the above to come the nitride series semiconductor laser shown in the shop drawings 1.
Next illustrates the nitride series semiconductor laser characteristic relevant with present embodiment has been carried out Simulation result.
As the simulation of semiconductor laser as used herein, the simulation of Maxwell equation, Poisson equation, レ-ト equation etc. of for example can having used the such employing of the LASTIP (LASer Technology IntegratedProgram) that sells by CrosslightSoftware Inc..
Fig. 4 is the profile of the structure of the nitride series semiconductor laser that uses in being illustrated in and simulating.As shown in Figure 4, having formed GaN resilient coating 5, n type AlGaN covering 6, thickness on GaN substrate 4 is the n type GaN light guide layer 7 of 100nm.
Then, on n type GaN light guide layer 7, formed the part active layer 8 that thickness is 3 trap layers, the thickness of the 3.5nm multiple quantum trap structure that to be 7.0nm be made of the barrier layer.
Moreover stacked in order thickness is the p type GaN contact layer 11 that the final barrier layer 1, thickness of 20nm is 100nm for the 20nmAl ratio of components is 0.20 p type AlGaN electron barrier layer 3, thickness is 100nm p type GaN light guide layer 9, p type AlGaN covering 10 that thickness is 400nm and thickness.The width of ridge 12 is formed 2.2 μ m.
In possessing the nitride series semiconductor laser of above structure, for the situation that final barrier layer 1 and barrier layer 2 whole materials is decided to be the InGaN of In ratio of components 0.02, be decided to be the situation of comparing the big GaN of band gap with the InGaN of In ratio of components 0.02 and with whole barrier layers 2 be decided to be GaN, the situation that only final barrier layer 1 is decided to be the InGaN of In ratio of components 0.02 simulates.
Fig. 5,6 shows the result of calculation of the simulation under above condition.Fig. 5 illustrates the figure that overflows the ratio of the electronics that becomes idle current for injected electrons from electron barrier layer 3.In addition, Fig. 6 is the figure that light output-current characteristics is shown.
" a " among Fig. 5 and Fig. 6 is the situation that final barrier layer 1 and barrier layer 2 all is decided to be the InGaN of In ratio of components 0.02, " b " is the situation that final barrier layer 1 and barrier layer 2 all is decided to be GaN, and " c " all is decided to be barrier layer 2 GaN, only final barrier layer 1 is decided to be the situation of the InGaN of In ratio of components 0.02.
As shown in Fig. 5 " b ", under whole situation of having used the big material of band gap (GaN) as final barrier layer 1 and barrier layer 2, electronics increases from the ratio that electron barrier layer 3 spills into the p side.Therefore, as shown in Fig. 6 " b ", can see the rising of threshold current, the decline of differential efficiency.
But as shown in Fig. 5 " c ", if use its band gap material littler than the band gap on barrier layer 2 (InGaN:In ratio of components 0.02) as final barrier layer 1, then the ratio of the electronics that overflows from electron barrier layer 3 has reduced significantly.Its result, as shown in Fig. 6 " c ", threshold current reduces, differential efficiency has risen.
In addition, by using the big GaN of band gap as barrier layer 2, can reduce from trap layer 18 and cross barrier layer 2 and the electronics that overflows, compare with the situation of " a ", differential efficiency has further improved.
For this analog result, the ratio that spills into the electronics of p side from electron barrier layer 3 roughly can be with discontinuous quantity to decide by the conduction band between final barrier layer 1 and the electron barrier layer 3.Therefore, if further reduce the band gap on final barrier layer 1, then can further reduce the ratio of the electronics that overflows from electron barrier layer 3.
As described above, for the semiconductor light-emitting elements relevant, make the band gap on final barrier layer 1 littler than the band gap on barrier layer 2 with present embodiment.
Therefore, owing to compare as final barrier layer 1 with barrier layer 2 identical materials with use, final barrier layer 1 can be with discontinuous quantity (electronic barrier) to become big with the conduction band of electron barrier layer 3, so can suppress to cross the electronics that electronic barrier overflows.
Have, in Fig. 5,6, the material on barrier layer 2 is decided to be InGaN or GaN, the material on final barrier layer 1 is decided to be InGaN.But, even any material in barrier layer 2 if use the material with band gap littler than the band gap on barrier layer 2 as final barrier layer 1, just can further reduce the ratio of overflowing from the electronics of electron barrier layer 3.
In addition, in the present embodiment, to be decided to be AlGaN electron barrier layer 3 with the layer that final barrier layer 1 is in the p side with joining, even but this layer is the less AlGaN of Al ratio of components or the optical waveguide layer 9 or the p type covering 10 that are made of GaN, also have same effect certainly.
That is,, also has same effect even do not have the nitride series semiconductor laser of the structure of AlGaN electron barrier layer 3 or optical waveguide layer 9.
For the nitride series semiconductor laser relevant with present embodiment 1, with trap layer 18 mutually ground connection be provided with final barrier layer 1.
Owing on trap layer 18, formed final barrier layer 1, so can prevent the crystalline deterioration of trap layer 18.
In addition since the thickness on final barrier layer 1 is chosen to different with the thickness of barrier layer 2, trap layer 18, so can further reduce the ratio of overflowing from the electronics of electron barrier layer 3.
＜execution mode 2 〉
Nitride series semiconductor laser for relevant with present embodiment has constituted final barrier layer 1 by the final barrier layers 13,19 of a plurality of parts (not shown in Fig. 1) in execution mode 1.
At this, the final barrier layer 13 of part can be called on the 1st final barrier layer of n type covering 6 one sides configuration, the final barrier layer 19 of part can be called the 2nd final barrier layer in the configuration of p type covering 6 one sides.
The final barrier layer 13 of part for example is decided to be the InGaN of thickness 10nm, In ratio of components 0.02, is formed on the part active layer 8.On the final barrier layer 13 of part, formed the final barrier layer 19 of part that the InGaN by thickness 10nm, In ratio of components 0.04 constitutes.
Because the relevant nitride series semiconductor laser of other structure and execution mode 1 is identical, the explanation of Therefore, omited repetition.
Fig. 7 shows near the energy band diagram the active layer 20 of the nitride relevant with present embodiment series semiconductor laser.And, in the energy band diagram shown in Figure 7, for the corresponding position of the structure of the nitride relevant series semiconductor laser with present embodiment attached with its structure be same symbol.
As shown in Figure 7, for the invention relevant, increased and to be with discontinuous quantity in the conductor of the final barrier layer 19 of part and electron barrier layer 3 with present embodiment.
That is, littler by the band gap that makes the final barrier layer 19 of part than the band gap on the barrier layer 2 beyond the final barrier layer 1, increased and can be with discontinuous quantity in the conductor of part final barrier layer 19 and electron barrier layer 3.
The ratio that spills into the electronics of p side from electron barrier layer 3 roughly can be with discontinuous quantity to decide by the final barrier layer 19 of part with the conduction band of electron barrier layer 3.
Therefore, same with execution mode 1, even the material that uses big band gap as barrier layer 2, also can suppress to cross the electronics that electron barrier layer 3 overflows.
In the semiconductor light-emitting elements relevant with present embodiment 2, the band gap on the final barrier layer 19 of part is than little with the band gap on the final barrier layer 13 of part of the final barrier layer of part 19 adjacency.
Therefore, compare with electron barrier layer 3, but can be with discontinuous quantity in the conductor of the final barrier layer of augmenting portion 19 and electron barrier layer 3 with final barrier layer 13, bonding part.
Its result can suppress to cross the electronics that electron barrier layer 3 overflows.
In the semiconductor light-emitting elements relevant with present embodiment 2, the material on the final barrier layer 19 of part is InGaN, is decided to be its band gap InGaN or the GaN bigger than the band gap on the final barrier layer 19 of part with the material on the final barrier layer 13 of part of the final barrier layer of part 19 adjacency.
Therefore, compare with electron barrier layer 3, but can be with discontinuous quantity in the conductor of the final barrier layer of augmenting portion 19 and electron barrier layer 3 with final barrier layer 13, bonding part.
Its result can suppress to cross the electronics that electron barrier layer 3 overflows.
Have, the band gap on the final barrier layer 13 of part can be same or identical degree with the band gap on barrier layer 2 in addition, final barrier layer 1 also again.
If making the band gap on the final barrier layer 13 of part can be same or identical degree with the band gap on barrier layer 2 also,, be roughly the same energy level then so can make the quantum level that in trap layer 18, forms owing in whole trap layers 18, can belt shape be roughly the same shape.Its result can reduce threshold current, improves differential efficiency.
＜execution mode 3 〉
For the nitride relevant with present embodiment series semiconductor laser, final barrier layer 1 is by following from the side that approaches trap layer 18 to approaching electron barrier layer 3 the InGaN formation that In ratio of components from 0.02 to 0.04 increases continuously.
Because the relevant nitride series semiconductor laser of other structure and execution mode 1 is identical, the explanation of Therefore, omited repetition.
Fig. 8 is near the energy band diagram the active layer 20 of the nitride relevant with present embodiment series semiconductor laser.As shown in Figure 8, the band gap on final barrier layer 1 diminishes continuously along with approaching electron barrier layer 3, and is littler than the band gap on barrier layer 2 at the locational band gap that joins with electron barrier layer 3.
Because the ratio of the electronics that overflows from electron barrier layer 3 roughly can be with discontinuous quantity to decide by final barrier layer 1 and the locational conduction band that electron barrier layer 3 joins, so also can obtain the effect equal in the present embodiment with execution mode 1.
Have, the material on final barrier layer 1 is not limited to InGaN again, as long as at gap, upper erengy band, the position material littler than the band gap on barrier layer 2 that joins with electron barrier layer 3.
＜execution mode 4 〉
In the present embodiment, used In
xAl
yGa
1-x-yN (0≤x＜1,0≤y≤1, x+y≤1) is as barrier layer 2.Other structure is identical with execution mode 1～3, and the repetitive description thereof will be omitted.
By using In
xAl
yGa
1-x-yN compares with the situation of having used InGaN as barrier layer 2, can increase the band gap on barrier layer 2.Therefore, can further suppress overflowing from the electronics of trap layer 18.Its result with compare in the situation shown in the execution mode 1～3, can obtain excellent nitride series semiconductor light-emitting elements such as derivative characteristic.
＜execution mode 5 〉
For the nitride series semiconductor laser relevant, in the nitride series semiconductor laser of execution mode 1～3, used GaN especially as barrier layer 2 with present embodiment.
By using GaN as barrier layer 2, compare with the situation of having used InGaN, band gap can be increased, and the good barrier layer of crystalline quality can be made.Its result can obtain excellent nitride series semiconductor lasers such as derivative characteristic.
Claims (26)
1. a semiconductor light-emitting elements has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that,
Above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms,
The band gap on final barrier layer that approaches most above-mentioned p type covering one side in above-mentioned a plurality of barrier layer is littler than the band gap on the barrier layer beyond the above-mentioned final barrier layer.
2. the semiconductor light-emitting elements described in claim 1 is characterized in that,
Above-mentioned final barrier layer has the final barrier layer of a plurality of parts,
The band gap on the final barrier layer of part that approaches most above-mentioned p type covering one side in the final barrier layer of above-mentioned a plurality of part is littler than the band gap on the barrier layer beyond the above-mentioned final barrier layer.
3. the semiconductor light-emitting elements described in claim 2 is characterized in that,
The band gap on the barrier layer beyond the band gap on the final barrier layer of part that joins with above-mentioned trap layer in the final barrier layer of above-mentioned a plurality of part and the above-mentioned final barrier layer is identical.
4. the semiconductor light-emitting elements described in claim 1 is characterized in that,
The band gap on above-mentioned final barrier layer diminishes when approaching above-mentioned p type covering continuously.
5. the semiconductor light-emitting elements described in each of claim 1 to 4 is characterized in that,
The material on the barrier layer beyond the above-mentioned final barrier layer is InAlGaN.
6. the semiconductor light-emitting elements described in each of claim 1 to 4 is characterized in that,
The material on the barrier layer beyond the above-mentioned final barrier layer is GaN.
7. a semiconductor light-emitting elements has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that,
Above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms,
Above-mentioned a plurality of barrier layer comprises the final barrier layer of approaching above-mentioned p type covering one side most,
Above-mentioned final barrier layer comprises the 1st final barrier layer that is configured in said n type covering one side and the 2nd final barrier layer that is configured in above-mentioned p type covering one side,
The band gap on the above-mentioned the 2nd final barrier layer is littler than the band gap on the barrier layer beyond the above-mentioned final barrier layer.
8. the semiconductor light-emitting elements described in claim 7 is characterized in that,
The band gap on the above-mentioned the 1st final barrier layer is identical degree with the band gap on barrier layer in addition, above-mentioned final barrier layer.
9. a semiconductor light-emitting elements has used the nitride series III-V compound semiconductor with the structure of clamping active layer between n type covering and p type covering, it is characterized in that,
Above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms,
Above-mentioned a plurality of barrier layer comprises the final barrier layer of approaching above-mentioned p type covering one side most,
The material on above-mentioned final barrier layer is InGaN, and the material on the barrier layer beyond the above-mentioned final barrier layer is GaN.
10. a semiconductor light-emitting elements has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that,
Above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms,
The final barrier layer of approaching above-mentioned p type covering one side in above-mentioned a plurality of barrier layer most comprises the final barrier layer of a plurality of parts,
The band gap on the final barrier layer of part 1 that approaches most above-mentioned p type covering one side in the final barrier layer of above-mentioned a plurality of part is than little with the band gap on the final barrier layer of part of the final barrier layer of above-mentioned part 1 adjacency.
11. the semiconductor light-emitting elements described in claim 10 is characterized in that,
With the band gap on the final barrier layer of part of the final barrier layer of above-mentioned part 1 adjacency and the band gap on the barrier layer beyond the above-mentioned final barrier layer is identical.
12. a semiconductor light-emitting elements has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that,
Above-mentioned active layer has a plurality of barrier layers and is clamped by above-mentioned barrier layer and the trap layer that forms,
The final barrier layer of approaching above-mentioned p type covering one side in above-mentioned a plurality of barrier layer most comprises the final barrier layer of a plurality of parts,
The material that approaches most the final barrier layer of part 1 of above-mentioned p type covering one side in the final barrier layer of above-mentioned a plurality of part is InGaN,
With the material on the final barrier layer of part of the final barrier layer of above-mentioned part 1 adjacency be band gap InGaN or the GaN bigger than the band gap on the final barrier layer of above-mentioned part 1.
13. a semiconductor light-emitting elements has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that,
The trap layer that above-mentioned active layer has a plurality of barrier layers and alternately is formed with above-mentioned barrier layer,
Possess:
Barrier layer, its band gap is bigger than the band gap on above-mentioned a plurality of barrier layers; And
The 1st layer, be provided between above-mentioned a plurality of barrier layer and the above-mentioned barrier layer and join with above-mentioned barrier layer, its band gap is littler and its band gap is bigger than the band gap of above-mentioned trap layer than the band gap on above-mentioned a plurality of barrier layers.
14. a semiconductor light-emitting elements has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that,
The trap layer that above-mentioned active layer has a plurality of barrier layers and alternately is formed with above-mentioned barrier layer,
Possess:
Optical waveguide layer, its band gap is bigger than the band gap on above-mentioned a plurality of barrier layers, joins with above-mentioned active layer one side of above-mentioned p type covering and is set up; And
The 1st layer, be provided between above-mentioned a plurality of barrier layer and the above-mentioned optical waveguide layer and join with above-mentioned optical waveguide layer, its band gap is littler and its band gap is bigger than the band gap of above-mentioned trap layer than the band gap on above-mentioned a plurality of barrier layers.
15. a semiconductor light-emitting elements has used the nitride series III-V compound semiconductor with the structure of having clamped active layer between n type covering and p type covering, it is characterized in that,
The trap layer that above-mentioned active layer has a plurality of barrier layers and alternately is formed with above-mentioned barrier layer,
Possess the 1st layer, the 1st layer is provided between above-mentioned a plurality of barrier layer and the above-mentioned p type covering and joins with above-mentioned p type covering, and its band gap is littler and its band gap is bigger than the band gap of above-mentioned trap layer than the band gap on above-mentioned a plurality of barrier layers.
16. the semiconductor light-emitting elements described in each of claim 13 to 15 is characterized in that,
With above-mentioned trap layer mutually ground connection be provided with above-mentioned the 1st layer.
17. the semiconductor light-emitting elements described in each of claim 13 to 15 is characterized in that,
Also possess the 2nd layer, the 2nd layer is provided between above-mentioned a plurality of barrier layer and above-mentioned the 1st layer and joins with above-mentioned the 1st layer, and its band gap is bigger or little and its band gap is bigger than the band gap of above-mentioned trap layer than above-mentioned the 1st layer band gap.
18. the semiconductor light-emitting elements described in claim 17 is characterized in that,
Above-mentioned the 2nd layer band gap is identical with the band gap on above-mentioned a plurality of barrier layers.
19. the semiconductor light-emitting elements described in each of claim 13 to 15 is characterized in that,
The material on above-mentioned a plurality of barrier layers is GaN, and above-mentioned the 1st layer material is InGaN.
20. the semiconductor light-emitting elements described in claim 19 is characterized in that,
Above-mentioned the 1st layer thickness is different with the thickness of above-mentioned a plurality of barrier layers and above-mentioned a plurality of trap layers.
21. the semiconductor light-emitting elements described in claim 19 is characterized in that,
Above-mentioned the 1st layer thickness is thicker than the thickness on above-mentioned a plurality of barrier layers.
22. the semiconductor light-emitting elements described in each of claim 13 to 15 is characterized in that,
The material on above-mentioned barrier layer is In
xGa
1-xN, the material of above-mentioned trap layer is In
yGa
1-yN, above-mentioned the 1st layer material is In
xGa
1-xN, In ratio of components x, y, z satisfy 0≤x＜z＜y＜1.
23. the semiconductor light-emitting elements described in claim 22 is characterized in that,
Above-mentioned the 1st layer thickness is different with the thickness of above-mentioned a plurality of barrier layers and above-mentioned a plurality of trap layers.
24. the semiconductor light-emitting elements described in claim 22 is characterized in that,
Above-mentioned the 1st layer thickness is thicker than the thickness on above-mentioned a plurality of barrier layers.
25. the semiconductor light-emitting elements described in claim 22 is characterized in that,
Above-mentioned In ratio of components x, y, z satisfy (y-z)＞(z-x).
26. the semiconductor light-emitting elements described in each of claim 13 to 15 is characterized in that,
The material on above-mentioned a plurality of barrier layers is In
xAl
yGa
1-x-yN (0≤x＜1,0≤y＜1, x+y≤1).
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|---|---|---|---|---|
| CN101290963B (en) * | 2007-04-16 | 2010-06-23 | 三菱电机株式会社 | Nitride semiconductor light-emitting device |
| CN103178170A (en) * | 2011-12-23 | 2013-06-26 | 新世纪光电股份有限公司 | Solid-state light emitting element |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101290963B (en) * | 2007-04-16 | 2010-06-23 | 三菱电机株式会社 | Nitride semiconductor light-emitting device |
| CN103178170A (en) * | 2011-12-23 | 2013-06-26 | 新世纪光电股份有限公司 | Solid-state light emitting element |
| CN103178170B (en) * | 2011-12-23 | 2016-03-02 | 新世纪光电股份有限公司 | Solid-state light emitting element |
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