阅读说明：本技术 一种宽温度工作dfb半导体激光器的制备方法 (Preparation method of DFB semiconductor laser working at wide temperature ) 是由 薛正群 杨重英 高家敏 吴林福生 李敬波 于 2019-11-21 设计创作，主要内容包括：本发明涉及一种宽温度工作DFB半导体激光器的制备方法,在InP衬底上依次生长缓冲层、下波导结构、下电子阻挡层、InGaAsP和AlGaInAs混合量子阱、上电子阻挡层、上波导结构、间隔层、长波长光栅层及光栅保护层,完成一次外延片的制备。接着在一次外延片上制备均匀光栅和光栅再生长形成完整的外延片,采用常规脊型波导结构工艺制备DFB激光器,实现宽温度工作的DFB半导体激光器。发明采用InGaAsP和AlGaInAs混合量子阱,充分利用AlGaInAs高温载流子限制效率高,以及InGaAsP量子阱增益谱的温度漂移系数小的特点来实现激光器宽温度范围内的单模工作,同时引入具有吸收特性的长波长光栅层来增加光栅对FP模式增益的吸收,进一步抑制FP起振,从而实现宽温度工作的单模激光器芯片。(The invention relates to a preparation method of a DFB semiconductor laser working at a wide temperature.A buffer layer, a lower waveguide structure, a lower electron barrier layer, an InGaAsP and AlGaInAs mixed quantum well, an upper electron barrier layer, an upper waveguide structure, a spacing layer, a long wavelength grating layer and a grating protection layer are sequentially grown on an InP substrate to finish the preparation of a primary epitaxial wafer. And then preparing a uniform grating on the primary epitaxial wafer and regrowing the grating to form a complete epitaxial wafer, and preparing the DFB laser by adopting a conventional ridge waveguide structure process to realize the DFB semiconductor laser working at a wide temperature. The invention adopts the InGaAsP and AlGaInAs mixed quantum well, fully utilizes the characteristics of high-temperature carrier limiting efficiency of AlGaInAs and small temperature drift coefficient of the gain spectrum of the InGaAsP quantum well to realize the single-mode operation of the laser in a wide temperature range, and simultaneously introduces the long-wavelength grating layer with absorption characteristic to increase the absorption of the grating to the FP mode gain, thereby further inhibiting the FP oscillation, and further realizing the single-mode laser chip which works in a wide temperature range.)

1. A method for preparing a DFB semiconductor laser working at wide temperature is characterized in that: the method comprises the following steps:

step S1: sequentially growing an N-InP buffer layer, 3 pairs of N-InP/N-InAlAs electronic barrier layers, an N-InAlGaAs lower waveguide layer, 5 layers of AlGaInAs and 4 layers of InGaAsP strain quantum wells, an InAlGaAs upper waveguide layer, 3 pairs of InAlAs/InP electronic barrier layers, a P-InP and P-InGaAsP corrosion stop layer, a P-InP space layer, a P-InGaAsP grating layer and a grating layer with the PL wavelength of 1285nm on an N-InP substrate sheet by a metal organic chemical vapor deposition technology, and finishing primary substrate growth by the P-InP protective layer;

step S2: the method of holographic exposure is adopted, and HBr: HNO 3: stirring and corroding the H2O solution at the temperature of 0 ℃ to form a grating with uniform period, removing residual photoresist and oxides on the surface of the sample, and putting the sample into a growth cavity of an MOCVD epitaxial furnace to finish epitaxial growth;

step S3: depositing a 200nm SiO2 dielectric layer on the surface of a sample by PECVD, photoetching, etching the dielectric layer and the InGaAs layer on the surface of the sample by adopting an RIE dry etching process, and then corroding to an etching stop layer by adopting H3PO4: HCl corrosive liquid to form a laser ridge structure; removing the SiO2 dielectric layer on the surface of the sample, and depositing a 400nm SiO2 passivation layer by PECVD;

step S4: preparing a ridge-structured laser: sequentially carrying out dissociation region photoetching, ridge-shaped opening and P-surface metal Ti/Pt/Au evaporation; and (3) physically grinding and thinning the N-type layer until the thickness is about 110 mu m, carrying out back treatment on the lower piece, evaporating N-side metal Ti/Pt/Au by using an electron beam, carrying out alloy 55s at the temperature of 420 ℃, dissociating into bar strips, carrying out clamping strip coating, realizing the reflectivity of about 1% by using an Al2O3/Si high-transmittance film, realizing the reflectivity of about 95% by using an Si/Al2O3/Si/Al2O3 high-reflection film, and finishing the preparation of the laser chip.

2. A method of fabricating a wide temperature operating DFB semiconductor laser as claimed in claim 1 wherein: in step S1, the thickness of the N-InP buffer layer is 500nm, the thickness of 3 pairs of N-InP/N-InAlAs electron blocking layers is 5nm/10nm, the thickness of the N-InAlGaAs lower waveguide layer is 50nm, the thickness of the InAlGaAs upper waveguide layer is 50nm, the thickness of 3 pairs of InAlAs/InP electron blocking layers is 10nm/5nm respectively, the thickness of the grown P-InP and P-InGaAsP corrosion stop layers is 50nm and 10nm respectively, the thickness of the grown P-InP space layer is 40nm, the thickness of the grown P-InGaAsP grating layer is 30nm, and the thickness of the grown P-InP protective layer is 10 nm.

3. A method of fabricating a wide temperature operating DFB semiconductor laser as claimed in claim 1 wherein: the process of completing the epitaxial growth in step S2 is: putting the sample into a growth cavity of an MOCVD epitaxial furnace, sequentially growing, growing a P-InP grating covering layer with the thickness of 1.6 mu m, growing a P-InGaAsP transition layer with the thickness of 50nm, and finally growing a doping concentration of 2 multiplied by 10 with the thickness of 200nm¹⁹cm^-3Thereby completing the epitaxial growth of the P-InGaAs ohmic contact layer.

Technical Field

The invention relates to the field of optical communication, in particular to a preparation method of a DFB semiconductor laser working at a wide temperature.

Background

With the rapid development of optical fiber communication, a coolless wide-temperature single-mode laser becomes a mainstream optical device in the future optical communication field, and is a key device for long-distance and large-capacity optical fiber communication. The method is widely applied to the fields of access networks, data meditations and the like.

The DFB laser adopts InP/InGaAsP and InP/AlGaInAs material systems; due to the high temperature characteristics of the InGaAsP quantum wells, InP/InGaAsP lasers typically employ buried heterojunction structures, which significantly increase the cost of laser fabrication. The InP/AlGaInAs generally adopts a ridge structure, but because the gain curve of the AlGaInAs material has a large temperature drift coefficient, the preparation of wide-temperature lasers becomes a difficult point.

Generally, an InP-based DFB laser needs to operate in a single mode without cooling within a wide temperature range to ensure the application of the laser in various environments; for a ridge waveguide structure laser, wavelength drift of a DFB single-mode light-emitting wavelength generated by temperature change is about 0.1 nm/DEG C, drift of an AlGaInAs quantum well gain spectrum along with temperature is 0.4-0.5 nm/DEG C, and the ridge waveguide structure DFB is difficult to work at a wide temperature due to large wavelength drift deviation of the two; the gain spectrum of the InGaAsP material varies with temperature around 0.3-0.4 nm/deg.C, however, a more costly buried structure process is required to improve high temperature characteristics.

The invention adopts the InGaAsP and AlGaInAs mixed quantum well, fully utilizes the characteristics of high AlGaInAs high-temperature carrier limiting efficiency and small temperature drift coefficient of the InGaAsP quantum well gain spectrum to realize single-mode operation of the laser within a wide temperature range, and simultaneously introduces the long-wavelength grating layer with absorption characteristic to increase the absorption of the grating on the FP mode gain, thereby further inhibiting the FP oscillation starting and further realizing the single-mode laser chip with wide temperature operation.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a method for manufacturing a DFB semiconductor laser operating at a wide temperature, in which the manufactured laser can reasonably set the emission wavelengths of two quantum wells, thereby realizing the wide temperature operation characteristic of the laser.

The invention is realized by adopting the following scheme: a preparation method of a DFB semiconductor laser working at wide temperature comprises the following steps:

step S1: sequentially growing an N-InP buffer layer, 3 pairs of N-InP/N-InAlAs electronic barrier layers, an N-InAlGaAs lower waveguide layer, 5 layers of AlGaInAs and 4 layers of InGaAsP strain quantum wells, an InAlGaAs upper waveguide layer, 3 pairs of InAlAs/InP electronic barrier layers, a P-InP and P-InGaAsP corrosion stop layer, a P-InP space layer, a P-InGaAsP grating layer and a grating layer PL wavelength of 1285nm on an N-InP substrate by an MOCVD (metal organic chemical vapor deposition) technology, and finishing the growth of a primary substrate;

step S2: the method of holographic exposure is adopted, and HBr: HNO 3: stirring and corroding the H2O solution at the temperature of 0 ℃ to form a grating with uniform period, removing residual photoresist and oxides on the surface of the sample, and putting the sample into a growth cavity of an MOCVD epitaxial furnace to finish epitaxial growth;

step S3: depositing a 200nm SiO2 dielectric layer on the surface of a sample by PECVD, photoetching, etching the dielectric layer and the InGaAs layer on the surface of the sample by adopting an RIE dry etching process, and then corroding to an etching stop layer by adopting H3PO4: HCl corrosive liquid to form a laser ridge structure; and removing the SiO2 dielectric layer on the surface of the sample, and depositing a 400nm SiO2 passivation layer by PECVD.

Step S4: preparing a ridge-structured laser: sequentially carrying out dissociation region photoetching, ridge-shaped opening and P-surface metal Ti/Pt/Au evaporation; and (3) physically grinding and thinning the N-type layer until the thickness is about 110 mu m, carrying out back treatment on the lower piece, evaporating N-side metal Ti/Pt/Au by using an electron beam, carrying out alloy 55s at the temperature of 420 ℃, dissociating into bar strips, carrying out clamping strip coating, realizing the reflectivity of about 1% by using an Al2O3/Si high-transmittance film, realizing the reflectivity of about 95% by using an Si/Al2O3/Si/Al2O3 high-reflection film, and finishing the preparation of the laser chip.

Further, in step S1, the thickness of the N-InP buffer layer is 500nm, the thickness of 3 pairs of N-InP/N-inalgas electron blocking layers is 5nm/10nm, the thickness of the N-inalgas lower waveguide layer is 50nm, the thickness of the inalgas upper waveguide layer is 50nm, the thickness of 3 pairs of inalgas/InP electron blocking layers is 10nm/5nm, the thickness of the grown P-InP and P-InGaAsP etch stop layers is 50nm and 10nm, the thickness of the grown P-InP spatial layer is 40nm, the thickness of the grown P-InGaAsP grating layer is 30nm, and the thickness of the grown P-InP protective layer is 10 nm.

Further, the process of completing the epitaxial growth in step S2 is: putting the sample into a growth cavity of an MOCVD epitaxial furnace, sequentially growing, growing a P-InP grating covering layer with the thickness of 1.6 mu m, growing a P-InGaAsP transition layer with the thickness of 50nm, and finally growing a doping concentration of 2 multiplied by 10 with the thickness of 200nm¹⁹cm^-3Thereby completing the epitaxial growth of the P-InGaAs ohmic contact layer.

Compared with the prior art, the invention has the following beneficial effects:

(1) the active region quantum well adopts two quantum wells of AlGaInAs and InGaAsP, and ensures that a single mode of the laser has enough gain to work in a wide temperature range by utilizing the difference of the drift velocity of the gain spectrums of the two quantum wells along with the temperature.

(2) According to the invention, a plurality of layers of InAlAs electronic blocking structures are added on two sides of the quantum well, so that the carrier limiting capability at high temperature is effectively improved, and the high-temperature characteristic is improved.

(3) The invention adjusts the PL wavelength of the grating, so that the absorption part of the grating absorbs the gain of the quantum well at low temperature, thereby further inhibiting the gain of the FP laser and realizing single mode.

(4) The laser prepared by the invention can reasonably set the light-emitting wavelengths of the two quantum wells, thereby realizing the characteristic of wide-temperature working of the laser.

Drawings

Fig. 1 is a diagram of a complete structure of an epitaxial material according to an embodiment of the present invention, wherein, along a growth direction, from bottom to top, the structure sequentially includes 1 an N-InP substrate, 2 an N-InP buffer layer, 3 an N-InP/N-InAlAs electronic barrier layer, 4 an N-inalgas lower waveguide layer, 5 an AlGaInAs and InGaAsP mixed quantum well, 6 an inalgas upper waveguide layer, 7 an InAlAs/InP electronic barrier layer, 8P-InP, 9 a P-InGaAsP etch stop layer, 10 a P-InP spatial layer, 11 a P-InGaAsP grating layer and a P-InP grating cap layer, 12 a P-InGaAsP transition layer, and 13 a P-InGaAsP ohmic contact layer.

Detailed Description

The invention is further explained below with reference to the drawings and the embodiments.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

As shown in fig. 1, the present embodiment provides a method for manufacturing a DFB semiconductor laser operating at a wide temperature, comprising the steps of:

step S1: sequentially growing an N-InP buffer layer 2, 3 pairs of N-InP/N-InAlAs electronic barrier layers 3, an N-InAlGaAs lower waveguide layer 4, 5 layers of AlGaInAs and 4 layers of InGaAsP strain quantum wells 5, an InAlGaAs upper waveguide layer 6, 3 pairs of InAlAs/InP electronic barrier layers 7, a P-InP layer 8, a P-InGaAsP corrosion stop layer 9, a P-InP space layer 10, a P-InGaAsP grating layer and a grating layer PL wavelength of 1285nm and finishing primary substrate growth by an MOCVD (metal organic chemical vapor deposition) technology on an N-InP substrate 1;

step S2: the method of holographic exposure is adopted, and HBr: HNO 3: stirring and corroding the H2O solution at the temperature of 0 ℃ to form a grating with uniform period, removing residual photoresist and oxides on the surface of the sample, and putting the sample into a growth cavity of an MOCVD epitaxial furnace to finish epitaxial growth;

step S3: depositing a 200nm SiO2 dielectric layer on the surface of a sample by PECVD, photoetching, etching the dielectric layer and the InGaAs layer on the surface of the sample by adopting an RIE dry etching process, and then corroding to an etching stop layer by adopting H3PO4: HCl corrosive liquid to form a laser ridge structure; and removing the SiO2 dielectric layer on the surface of the sample, and depositing a 400nm SiO2 passivation layer by PECVD.

And S4, preparing a conventional ridge-structured laser, namely sequentially carrying out photoetching of a dissociation region, ridge opening and evaporation of P-surface metal Ti/Pt/Au (500/500/3000 Å), physically grinding to reduce the thickness of an N-type layer to be about 110 mu m, carrying out back treatment on a lower sheet, evaporating N-surface metal Ti/Pt/Au (500/1000/3000 Å) by using an electron beam, dissociating the N-surface metal Ti/Pt/Au into bars at the temperature of 420 ℃ for 55S by using an alloy, carrying out clamping bar coating, realizing the reflectivity of about 1% by using an Al2O3/Si high-transmittance film, realizing the reflectivity of about 95% by using an Si/Al2O3/Si/Al2O3 high-reflection film, and finishing the preparation of a laser chip.

In this embodiment, in step S1, the thickness of the N-InP buffer layer 2 is 500nm, the thickness of the 3 pairs of N-InP/N-inalgas electron blocking layers 3 is 5nm/10nm, the thickness of the N-inalgas lower waveguide layer 4 is 50nm, the thickness of the inalgas upper waveguide layer 6 is 50nm, the thicknesses of the 3 pairs of inalgas/InP electron blocking layers 7 are 10nm/5nm, the thicknesses of the grown P-InP and P-InGaAsP etch stop layers are 50nm and 10nm, the thickness of the grown P-InP space layer 10 is 40nm, the thickness of the grown P-InGaAsP grating layer is 30nm, and the thickness of the grown P-InP protective layer is 10 nm.

In this embodiment, the process of completing the epitaxial growth in step S2 is: putting the sample into a growth cavity of an MOCVD epitaxial furnace, sequentially growing a P-InP grating layer covering layer (the grating layer and the grating covering layer form 11 in the figure) with the thickness of 1.6 mu m, growing a P-InGaAsP transition layer 12 with the thickness of 50nm, and finally growing a doping concentration of 2 multiplied by 10 with the thickness of 200nm¹⁹cm^-3Thereby completing the epitaxial growth of the P-InGaAs ohmic contact 13 layer.

Preferably, in this embodiment, a buffer layer, a lower waveguide structure, a lower electron blocking layer, an InGaAsP and AlGaInAs mixed quantum well, an upper electron blocking layer, an upper waveguide structure, a spacer layer, a long wavelength grating layer, and a grating protection layer are sequentially grown on an InP substrate to complete the preparation of a primary epitaxial wafer. And then preparing a uniform grating on the primary epitaxial wafer and regrowing the grating to form a complete epitaxial wafer, and preparing the DFB laser by adopting a conventional ridge waveguide structure process to realize the DFB semiconductor laser working at a wide temperature. The InGaAsP and AlGaInAs mixed quantum well is adopted, the advantage and the characteristic of two materials are utilized, the single-mode operation of the laser within a wide temperature range is realized, a long-wavelength grating layer is further adopted to absorb part of FP gain, and the FP mode is further inhibited; multiple barrier layers are employed to improve high temperature carrier confinement characteristics.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.