Laser active district, semiconductor laser and preparation method thereof
Technical field
The present invention relates to semi-conductor photoelectronic field, particularly relate to a kind of active area of laser, the semiconductor laser comprising this active area and preparation method thereof.
Background technology
In high speed optical fiber communication field, 1310nmInGaAsP/InP Strained Quantum Well Lasers has obtained extensive and deep research.Theoretical prediction, compare Lattice Matching and compressive strain quantum well, transverse magnetic (TM) modal gain that tensile strain quantum well provides exceedes transverse electric field (TE) modal gain that compressive strain quantum well provides, adopt tensile strain quantum well can obtain better device performance, as lower threshold current, the higher differential gain and less auger recombination speed etc.
At present, realize business-like 1310nm semiconductor laser based on InGaAsP/InP material system, but InGaAsP/InP laser is still difficult to temperature more than 85 DEG C without refrigeration work.In order to address this problem, the substitution material system of the optical band that the another kind developed covers centered by 1310nm is InGaNAs/GaAs, so far, for InGaNAs/GaAs material system, N component is brought up to 10% still very difficult, and mix atom N and easily introduce defect, the laser therefore based on this material system is also in the starting stage.
Summary of the invention
For the above-mentioned the deficiencies in the prior art mentioned, the present invention proposes a kind of laser active district and comprise the semiconductor laser of described active area, described semiconductor laser can realize effective restriction and charge carrier being uniformly distributed in active area to injecting charge carrier simultaneously, there is lower threshold current and the differential gain of Geng Gao, there is lower auger recombination speed and can realize without refrigeration work.
To achieve these goals, present invention employs following technical scheme:
A kind of laser active district is provided, described active area comprises a multi-quantum pit structure, and in described multi-quantum pit structure, the material of potential well layer is InGaAsP, and in described quantum well structure, the material of barrier layer is InGaAlAs, the periodicity of described multi-quantum pit structure is the scope of K, K is 3 ~ 20.
Preferably, described active area is the doping of P type.
Preferably, the material In of described potential well layer
1-xga
xas
yp
1-yin, x=51%, y=79%, have 1% tensile strain; The material In of described barrier layer
1-x-yga
xal
yin As, x=11.2%, y=28.8%, have 0.5% compressive strain.
Preferably, the thickness of described potential well layer is 6 ~ 10nm, and the thickness of described barrier layer is 10 ~ 20nm.
Preferably, the periodicity of described multi-quantum pit structure is 6.
Present invention also offers a kind of semiconductor laser comprising active area as above.
Preferably, this semiconductor laser comprises substrate that lamination successively arranges, First Transition layer, the first limiting layer, first wave conducting shell, described active area, Second Wave conducting shell, the second limiting layer, the second transition zone and ohmic contact layer.
Preferably, the material of described substrate is InP, the material of described First Transition layer and the second transition zone is InGaAlAs, the material of described first limiting layer and the second limiting layer is InAlAs, the material of described first wave conducting shell and Second Wave conducting shell is InGaAlAs, and described ohmic contact layer is material is InGaAs.
Preferably, the material of described substrate is N-type InP; The material In of described First Transition layer
1-x-yga
xal
yas adopts the structure of N-type doping, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 47% according to the direction away from described substrate from 39%; The material In of described first limiting layer
xal
1-xas adopts the structure of N-type doping, wherein, and x=53%; The material In of described first wave conducting shell
1-x-yga
xal
yas adopts the structure of undoped, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 28.8% according to the direction away from described substrate from 47%; The material In of described Second Wave conducting shell
1-x-yga
xal
yas adopts the structure of the doping of P type, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 47% according to the direction away from described substrate from 28.8%; The material In of described second limiting layer
xal
1-xas adopts the structure of P type doping, wherein, and x=53%; The material In of described second transition zone
1-x-yga
xal
yas adopts the structure of the doping of P type, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 39% according to the direction away from described substrate from 47%; The material InGaAs of described ohmic contact layer adopts the structure of P type doping.
Another object of the present invention is also the manufacture method providing semiconductor laser as above, comprises step:
One, MOCVD technique or MBE technique is adopted to grow following each structure sheaf successively:
A) in InP substrate, grow InGaAlAs First Transition layer;
B) InAlAs first limiting layer;
C) InGaAlAs first wave conducting shell;
D) active area:
D1) InGaAlAs barrier layer;
D2) InGaAsP potential well layer;
E) steps d 1 is repeated) and steps d 2), until grown the active area of the multi-quantum pit structure with K cycle, wherein the scope of K has been 3 ~ 20;
F) InGaAlAs Second Wave conducting shell;
G) InAlAs second limiting layer;
H) InGaAlAs second transition zone;
I) InGaAs ohmic contact layer.
Wherein, the material of described substrate is N-type InP; The material In of described First Transition layer
1-x-yga
xal
yas adopts the structure of N-type doping, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 47% according to the direction away from described substrate from 39%; The material In of described first limiting layer
xal
1-xas adopts the structure of N-type doping, wherein, and x=53%; The material In of described first wave conducting shell
1-x-yga
xal
yas adopts the structure of undoped, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 28.8% according to the direction away from described substrate from 47%; The material In of described Second Wave conducting shell
1-x-yga
xal
yas adopts the structure of the doping of P type, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 47% according to the direction away from described substrate from 28.8%; The material In of described second limiting layer
xal
1-xas adopts the structure of P type doping, wherein, and x=53%; The material In of described second transition zone
1-x-yga
xal
yas adopts the structure of the doping of P type, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 39% according to the direction away from described substrate from 47%; The material InGaAs of described ohmic contact layer adopts the structure of P type doping.
Two, after completing each structure sheaf of growth, first by electron beam evaporation deielectric-coating, then P-type electrode window is formed through conventional photoetching, etching process, and thermal evaporation Au/Zn/Au, form P type Ohm contact electrode; After InP substrate face adopts chemical reduction, evaporate Au/Ge/Ni, form N-type ohmic contact layer; Last cleavage forms chip of laser, then chip is sintered to heat sink on, connecting lead wire, obtains described semiconductor laser.
Adopt InGaAlAs material as barrier layer, InGaAsP material, as well layer, not only can obtain large conduction band band rank ratio (Δ E
c≈ 0.72 Δ E
g), suppress electronics overflow, can obtain distributing between very uniform trap to the weak restriction in hole simultaneously, thus have lower threshold current and the gain of Geng Gao.InGaAsP/InGaAlAs tensile strain quantum well can provide TM Mode for Laser to export, and reduces threshold current further, improves the differential gain and has less auger recombination speed.In addition, P type is carried out to active area and transports doped with helping hole, the higher differential gain can be obtained, be conducive to the modulating characteristic improving device.Therefore, the InGaAsP/InGaAlAs tensile strain quantum well of P type doping becomes the preferred material of 1310nmTM pattern high-speed laser active area.
Compared with prior art, tool of the present invention has the following advantages:
1, the present invention adopts InGaAsP/InGaAlAs material system to make tensile strain quantum well structure as laser as active area, and the laser comprising this active area has lower threshold current, higher characteristic temperature, can realize without refrigeration work; There is the higher differential gain, TM Mode for Laser can be provided to export; There is larger conduction band band rank ratio, can realize effectively limiting and charge carrier being uniformly distributed between trap injection charge carrier simultaneously, improve laser modulation characteristic;
Even if 2, the active area of multi-quantum pit structure provided by the invention adopts the design of heavy hole energy level alignment between strain-compensated quantum well structure and trap, base---trap, build between heavy hole energy level be in same energy position, can threshold current be reduced, improve slope efficiency and modulation bandwidth;
3, the active area of multi-quantum pit structure provided by the invention adopts the doping of P type, charge carrier is distributed between trap more even, can expand modulation bandwidth, improve the modulating characteristic of laser;
4, semiconductor laser provided by the invention introduces gradual transition layer respectively between substrate and limiting layer and between ohmic contact layer and limiting layer, Electric Field Distribution can be made more mild, improve Carrier Injection Efficiency.
Accompanying drawing explanation
Fig. 1 is the structural representation in the laser active district of preparing in one embodiment of the invention.
Fig. 2 is the structural representation of the semiconductor laser prepared in one embodiment of the invention.
Embodiment
Below in conjunction with accompanying drawing, by embodiment, the present invention will be further described.
As previously mentioned, in view of the deficiency that prior art exists, the present invention proposes a kind of laser active district and comprise the semiconductor laser of described active area, described semiconductor laser can realize effective restriction and charge carrier being uniformly distributed in active area to injecting charge carrier simultaneously, there is lower threshold current and the differential gain of Geng Gao, there is lower auger recombination speed and realize without refrigeration work.
This laser active district comprises a multi-quantum pit structure, in described multi-quantum pit structure, the material of potential well layer is InGaAsP, in described quantum well structure, the material of barrier layer is InGaAlAs, the periodicity of described multi-quantum pit structure is K, the scope of K is 3 ~ 20, the thickness of described potential well layer is 6 ~ 10nm, and the thickness of described barrier layer is 10 ~ 20nm.
Particularly, the present embodiment is described in detail as an example by with the active area of the multi-quantum pit structure in 6 cycles.
As shown in Figure 1, this active area 07 is made up of the multi-quantum pit structure in 6 cycles, comprises 7 layers of barrier layer 05 and 6 layers of potential well layer 06 of alternative stacked setting; The material In of described potential well layer 06
1-xga
xas
yp
1-yin, x=51%, y=79%, have 1% tensile strain; The material In of described barrier layer 05
1-x-yga
xal
yin As, x=11.2%, y=28.8%, have 0.5% compressive strain; Wherein, the thickness of each potential well layer 06 is 10nm, and the thickness of each barrier layer 05 is 20nm; The material InGaAsP of the potential well layer 06 and material InGaAlAs of barrier layer 05 all adopts P type to adulterate.
In the present embodiment, the active area of multi-quantum pit structure adopts the doping of P type, charge carrier is distributed between trap more even, can expand modulation bandwidth, improve the modulating characteristic of laser.
The present embodiment additionally provides a kind of semiconductor laser, and this semiconductor laser comprises active area as above.Particularly, as shown in Figure 2, this semiconductor laser comprises InP substrate 01 that lamination successively arranges, InGaAlAs First Transition layer 02, InAlAs first limiting layer 03, InGaAlAs first wave conducting shell 04, active area 07 as above, InGaAlAs Second Wave conducting shell 08, InAlAs second limiting layer 09, InGaAlAs second transition zone 10 and InGaAs ohmic contact layer 11.
Wherein, the material of described substrate 01 is N-type InP; The material In of described First Transition layer 02
1-x-yga
xal
yas adopts the structure of N-type doping, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 47% according to the direction away from described substrate 01 from 39%; The material In of described first limiting layer 03
xal
1-xas adopts the structure of N-type doping, wherein, and x=53%; The material In of described first wave conducting shell 04
1-x-yga
xal
yas adopts the structure of undoped, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 28.8% according to the direction away from described substrate 01 from 47%; The material In of described Second Wave conducting shell 08
1-x-yga
xal
yas adopts the structure of the doping of P type, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 47% according to the direction away from described substrate 01 from 28.8%; The material In of described second limiting layer 09
xal
1-xas adopts the structure of P type doping, wherein, and x=53%; The material In of described second transition zone 10
1-x-yga
xal
yas adopts the structure of the doping of P type, content gradually variational, and wherein, (1-x-y)=53%, y is gradient to 39% according to the direction away from described substrate 01 from 47%; The material InGaAs of described ohmic contact layer 11 adopts the structure of P type doping.
The semiconductor laser that the present embodiment provides introduces gradual transition layer respectively between substrate and limiting layer and between ohmic contact layer and limiting layer, Electric Field Distribution can be made more mild, improve Carrier Injection Efficiency.
Introduce the manufacture method of semiconductor laser as above below, the method specifically comprises step:
One, MOCVD technique or MBE technique is adopted to grow following each structure sheaf successively:
(1) the N-type doping content about 1 × 10 that growth 0.1 μm is thick in N-type InP substrate 01
18cm
-3, content gradually variational InGaAlAs First Transition layer 02, described In
1-x-yga
xal
yin As First Transition layer 02, the component y of the component (1-x-y)=53%, Al of In is gradient to 47% according to the direction away from described substrate 01 from 39%;
(2) the N-type doping content about 1 × 10 that growth 0.4 μm is thick
18cm
-3inAlAs first limiting layer 03, described In
xal
1-xin As first limiting layer 03, the component x=53% of In;
(3) undoped that growth 0.15 μm is thick, the InGaAlAs first wave conducting shell 04, described In of content gradually variational
1-x-yga
xal
yin As first wave conducting shell 04, the component y of the component (1-x-y)=53%, Al of In is gradient to 28.8% according to the direction away from described substrate 01 from 47%;
(4) the P type doping content that alternating growth 20nm is thick is 3 × 10
17cm
-3inGaAlAs barrier layer 05 (totally 7 layers) and 10nm thick P type doping content be 3 × 10
17cm
-3inGaAsP potential well layer 06 (totally 6 layers), formed and there is the active area 07 of 6 cycle multi-quantum pit structures; Wherein, the material In of described potential well layer 06
1-xga
xas
yp
1-yin, x=51%, y=79%, have 1% tensile strain; The material In of described barrier layer 05
1-x-yga
xal
yin As, x=11.2%, y=28.8%, have 0.5% compressive strain;
(5) the P type doping content that growth 0.15 μm is thick is 3 × 10
17cm
-3, the InGaAlAs Second Wave conducting shell 08, described In of content gradually variational
1-x-yga
xal
yin As Second Wave conducting shell 08, the component y of the component (1-x-y)=53%, Al of In is gradient to 47% according to the direction away from described substrate 01 from 28.8%;
(6) the P type doping content that growth 0.4 μm is thick is about 1 × 10
18cm
-3inAlAs second limiting layer 09, described In
xal
1-xin As second limiting layer 09, the component x=53% of In;
(7) the P type doping content about 1 × 10 that growth 0.1 μm is thick
18cm
-3, InGaAlAs second transition zone 10, described In of content gradually variational
1-x-yga
xal
yin As second transition zone 10, the component y of the component (1-x-y)=53%, Al of In is gradually gradient to 39% from 47% according to away from described substrate 01 direction;
(8) the P type doping content that growth 0.2 μm is thick is about 2 × 10
19cm
-3inGaAs ohmic contact layer 11.
Two, after completing each structure sheaf of growth, the thick SiO of electron beam evaporation 0.1 μm is first passed through
2deielectric-coating, then form P-type electrode window (width is 200 μm) through conventional photoetching, etching process, and thermal evaporation Au/Zn/Au, form P type Ohm contact electrode; After InP substrate face adopts chemical reduction to about 100 μm, evaporate Au/Ge/Ni, form N-type ohmic contact layer; Last cleavage forms chip of laser, then chip is sintered to heat sink on, connecting lead wire, obtains described semiconductor laser.
In above-described embodiment, each step all adopts MOCVD (MetalOrganicChemicalVaporDeposition, metallo-organic compound chemical gaseous phase deposition) or MBE (MolecularBeamEpitaxy, molecular beam epitaxy) mode grow; According to MOCVD technique, then each layer N-type foreign atom is Si, Se, S or Te, and P type foreign atom is Zn, Mg or C; According to MBE technique, then each layer N-type foreign atom is Si, Se, S, Sn or Te, and P type foreign atom is Be, Mg or C.
The present invention adopts InGaAsP/InGaAlAs material system to make tensile strain quantum well structure as laser as active area, even if adopt the design of heavy hole energy level alignment between strain-compensated quantum well structure and trap, base---trap, build between heavy hole energy level be in same energy position, can threshold current be reduced, improve slope efficiency and modulation bandwidth; The laser comprising this active area has lower threshold current, higher characteristic temperature, can realize without refrigeration work; There is the higher differential gain, TM Mode for Laser can be provided to export; There is larger conduction band band rank ratio, can realize effectively limiting and charge carrier being uniformly distributed between trap injection charge carrier simultaneously, improve laser modulation characteristic.
It should be noted that, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operating space, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or equipment and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or equipment.When not more restrictions, the key element limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment comprising described key element and also there is other identical element.
The above is only the embodiment of the application; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the application's principle; can also make some improvements and modifications, these improvements and modifications also should be considered as the protection range of the application.