阅读说明：本技术 一种dfb激光器外延结构及其生长方法 (DFB laser epitaxial structure and growth method thereof ) 是由 单智发 张永 姜伟 陈阳华 方天足 于 2020-04-20 设计创作，主要内容包括：一种DFB激光器外延结构,包括InP基底,在所述InP基底依次采用MOCVD沉积的InP外延层、AlInAsP插入层、AlInAs外延层、N-AlGaInAs波导层、AlGaInAs MQW、P-AlGaInAs波导层、P-AlInAs限制层、P-InP限制层、腐蚀阻挡层、InP联接层、光栅层、InGaAsP势垒过度层、以及InGaAs欧姆接触层；本方案设计的DFB激光器外延结构在所述InP外延层中插入若干与InP晶格匹配的InGaAs薄层,一方面可以降低InP基底位错对MQW的影响,另一方面,可以抑制基底中杂质的脱出,从而获得高制量的MQW,提高激光器的可靠性。(A DFB laser epitaxial structure comprises an InP substrate, wherein an InP epitaxial layer, an AlInAsP insertion layer, an AlInAs epitaxial layer, an N-AlGaInAs waveguide layer, an AlGaInAs MQW, a P-AlGaInAs waveguide layer, a P-AlInAs limiting layer, a P-InP limiting layer, a corrosion barrier layer, an InP connecting layer, a grating layer, an InGaAsP barrier transition layer and an InGaAs ohmic contact layer which are deposited on the InP substrate by MOCVD are sequentially adopted; according to the epitaxial structure of the DFB laser, the plurality of InGaAs thin layers matched with InP lattices are inserted into the InP epitaxial layer, so that the influence of dislocation of an InP substrate on the MQW can be reduced, and the impurity in the substrate can be inhibited from being removed, so that the MQW with high production quantity can be obtained, and the reliability of the laser is improved.)

1. A DFB laser epitaxial structure comprises an InP substrate, wherein an InP epitaxial layer, an AlInAsP insertion layer, an AlInAs epitaxial layer, an N-AlGaInAs waveguide layer, an AlGaInAs MQW, a P-AlGaInAs waveguide layer, a P-AlInAs limiting layer, a P-InP limiting layer, a corrosion barrier layer, an InP connecting layer, a grating layer, an InGaAsP barrier transition layer and an InGaAs ohmic contact layer which are deposited on the InP substrate by MOCVD are sequentially adopted; the method is characterized in that: and a plurality of InGaAs thin layers which are matched with InP lattices are inserted into the InP epitaxial layer.

2. A DFB laser epitaxy structure according to claim 1, wherein: on the InP substrate, the first layer adopts an InGaAs epitaxial layer, and then adopts an InP epitaxial layer.

3. A DFB laser epitaxy structure according to claim 1, wherein: the number of the inserted InGaAs thin layers is not less than 6.

4. A DFB laser epitaxy structure according to claim 1, wherein: the conductivity of the InP substrate is 2-8x10¹⁸cm^-2。

5. A growth method of a DFB laser epitaxial structure comprises the following steps: the method is characterized in that: which comprises the following steps:

the method comprises the following steps: with the conductivity of 2-8x10¹⁸cm^-2The InP substrate is used as a growth substrate, the InP substrate is put into an MOCVD system for growth, the pressure of a reaction chamber is 50mbar, the growth temperature is 670 ℃, hydrogen is used as carrier gas, and trimethyl indium (TMIn), trimethyl gallium (TMGa), trimethyl aluminum (TMAl), diethyl zinc (DeZn), silane (SiH 4), arsine (AsH 3), phosphane (PH 3) and the like are used as reaction source gases;

step two: after an InP substrate is placed in a reaction chamber, baking is carried out at 670 ℃ under the atmosphere of phosphane, the flow rate of the phosphane is 1800sccm, and after 10 minutes, an InGaAs epitaxial layer starts to grow, wherein the flow rate of trimethyl indium is 100sccm, and the flow rate of trimethyl gallium is 8 sccm;

step three: after the InGaAs epitaxial layer is grown, introducing phosphine and trimethylindium to start to grow the InP epitaxial layer, wherein the flow rate of the trimethylindium is 300sccm, and the flow rate of the phosphine is 1800 sccm; after the growth of the InP epitaxial layer is finished, growing the InGaAs epitaxial layer again, then growing the 100nm InP epitaxial layer again, and circulating the steps;

step four: on the premise of the third step, closing the trimethylindium and the silane, starting the arsine, wherein the flow rate of the arsine is 600sccm, and simultaneously reducing the flow rate of the phosphane to 300 sccm; after 3 minutes, introducing trimethyl indium and silane to start growing, and then growing an AlInAsP epitaxial layer with the thickness of 10nm, wherein the Source flow of the trimethyl indium is 100 sccm;

step five: on the premise of the fourth step, after 200 seconds, the phosphane is closed, the flow rates of trimethyl aluminum, trimethyl indium and silane are linearly increased, and an AlInAs epitaxial layer starts to grow;

step six: after the growth of the AlInAs epitaxial layer is finished, an N-AlGaInAs waveguide layer, an AlGaInAsMQW layer, a P-AlGaInAs waveguide layer, a P-AlInAs limiting layer, a P-InP limiting layer and an etching barrier layer are sequentially grown, a grating is manufactured, and an InP connecting layer, an InGaAsP barrier transition layer and an InGaAs ohmic contact layer are grown by adopting a pulse deposition method.

6. The method of claim 1, wherein the step of growing the epitaxial structure of the DFB laser comprises the steps of: in the third step, specifically, the epitaxial layer with the thickness of 5nm and the InP epitaxial layer with the thickness of 100nm are alternately and circularly increased, and the circulation frequency is 8 times.

7. The method of claim 6, wherein the step of growing the epitaxial structure of the DFB laser comprises the steps of: and the process of alternately and circularly growing the 5nm epitaxial layer and the 100nm InP epitaxial layer is finally ended by finishing the growth of the 100nm InP epitaxial layer.

Technical Field

The invention belongs to the technical field of semiconductor photoelectron, and particularly relates to a DFB laser epitaxial structure and a growth method thereof.

Background

The Distributed Feedback laser (Distributed Feedback L aser, DFB laser for short) has good single longitudinal mode characteristic, the line width is less than 1MHz, the side mode suppression ratio can reach more than 40 dB, and the Distributed Feedback laser has wide application in the field of 5G mobile communication optical fiber communication network and data center optical interconnection;

with the increasing approach of 5G commercial use, a dynamic single-mode distributed feedback laser (DFB-L D) with narrow line width, high side-mode rejection ratio and high modulation rate becomes the preferred light source, the DFB adopts grating modulation with periodically changing refractive index, has good single longitudinal mode characteristics, the side-mode rejection ratio can reach more than 50dB, the modulation rate can reach more than 50Gb/S, and can meet the application requirements of 5G mobile network high rate/low delay, the wavelength of the DFB laser for high-speed optical communication is generally 1310 nm and 1550 nm, the DFB laser generally adopts 1310 InP growth substrate, and quantum well of AlGaInAs is adopted as an active layer, because the extrinsic base material has certain dislocation density and impurities, such as N-InP substrate generally adopts S as doping, P-InP substrate generally adopts Zn as doping, SI-InP substrate generally adopts Fe as doping, during the epitaxial growth process, the surface layer doping can volatilize from the substrate and be incorporated into the growing crystal lattice, and if the MQW grows, the impurity content is high, the material quality deteriorates, and thus the device growth performance deteriorates.

Meanwhile, AlGaInAs series materials on an InP substrate are difficult to be prepared by MOCVD equipment for the following reasons: (1) an oxidation layer possibly existing on the surface of the InP substrate causes the quality of the MQW material to be poor; (2) impurities doped in the extrinsic InP substrate can be removed during growth, so that the growth quality of the material is influenced; (3) there is atomic nonlinear mixing at the As-P switching interface.

Therefore, it is necessary to design a DFB laser epitaxial structure to solve the above technical problems.

Disclosure of Invention

To overcome the above-mentioned deficiencies in the prior art, the present invention aims to provide a DFB laser epitaxial structure.

In order to achieve the above objects and other related objects, the present invention provides the following technical solutions: a DFB laser epitaxial structure comprises an InP substrate, wherein an InP epitaxial layer, an AlInAsP insertion layer, an AlInAs epitaxial layer, an N-AlGaInAs waveguide layer, an AlGaInAs MQW, a P-AlGaInAs waveguide layer, a P-AlInAs limiting layer, a P-InP limiting layer, a corrosion barrier layer, an InP connecting layer, a grating layer, an InGaAsP barrier transition layer and an InGaAs ohmic contact layer which are deposited on the InP substrate by MOCVD are sequentially adopted; the method is characterized in that: and a plurality of InGaAs thin layers which are matched with InP lattices are inserted into the InP epitaxial layer.

Preferably, on the InP substrate, the InGaAs epitaxial layer is used as the first layer, and then the InP epitaxial layer is used.

Preferably, the number of the inserted InGaAs thin layers is not less than 6.

Preferably, the conductivity of the InP substrate is 2-8x10¹⁸cm^-2。

The invention also discloses a growth method of the epitaxial structure of the DFB laser, which comprises the following steps: the method comprises the following steps:

the method comprises the following steps: taking an InP substrate with the conductivity of 2-8x1018cm-2 as a growth substrate, firstly putting the InP substrate into an MOCVD system for growth, wherein the pressure of a reaction chamber is 50mbar, the growth temperature is 670 ℃, hydrogen is taken as a carrier gas, and trimethyl indium (TMIn), trimethyl gallium (TMGa), trimethyl aluminum (TMAl), diethyl zinc (DeZn), silane (SiH 4), arsine (AsH 3), phosphane (PH 3) and the like are taken as reaction source gases;

step two: after an InP substrate is placed in a reaction chamber, baking is carried out at 670 ℃ under the atmosphere of phosphane, the flow rate of the phosphane is 1800sccm, and after 10 minutes, an InGaAs epitaxial layer starts to grow, wherein the flow rate of trimethyl indium is 100sccm, and the flow rate of trimethyl gallium is 8 sccm;

step three: after the InGaAs epitaxial layer is grown, introducing phosphine and trimethylindium to start to grow the InP epitaxial layer, wherein the flow rate of the trimethylindium is 300sccm, and the flow rate of the phosphine is 1800 sccm; after the growth of the InP epitaxial layer is finished, growing the InGaAs epitaxial layer again, then growing the 100nm InP epitaxial layer again, and circulating the steps;

step four: on the premise of the third step, closing the trimethylindium and the silane, starting the arsine, wherein the flow rate of the arsine is 600sccm, and simultaneously reducing the flow rate of the phosphane to 300 sccm; after 3 minutes, introducing trimethyl indium and silane to start growing, and then growing an AlInAsP epitaxial layer with the thickness of 10nm, wherein the Source flow of the trimethyl indium is 100 sccm;

step five: on the premise of the fourth step, after 200 seconds, the phosphane is closed, the flow rates of trimethyl aluminum, trimethyl indium and silane are linearly increased, and an AlInAs epitaxial layer starts to grow;

step six: after the growth of the AlInAs epitaxial layer is finished, an N-AlGaInAs waveguide layer, an AlGaInAsMQW layer, a P-AlGaInAs waveguide layer, a P-AlInAs limiting layer, a P-InP limiting layer and an etching barrier layer are sequentially grown, a grating is manufactured, and an InP connecting layer, an InGaAsP barrier transition layer and an InGaAs ohmic contact layer are grown by adopting a pulse deposition method.

Preferably, in the third step, specifically, the epitaxial layer with the thickness of 5nm and the InP epitaxial layer with the thickness of 100nm are alternately and cyclically increased, and the cycle number is 8.

Preferably, the process of alternately and cyclically growing the 5nm epitaxial layers and the 100nm InP epitaxial layers ends with the growth completion of the 100nm InP epitaxial layers.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the invention provides a DFB laser epitaxial structure and a growth method thereof.A plurality of InGaAs thin layers matched with InP lattices are inserted when an InP epitaxial layer grows on an InP substrate, and on the InP substrate, the first layer needs to grow the InGaAs epitaxial layer firstly and then grow the InP epitaxial layer again; the insertion of the InGaAs thin layer can reduce the influence of the dislocation of the InP substrate on the MQW, and can inhibit the impurity in the substrate from being taken out, thereby obtaining the MQW with high production quantity and improving the reliability of the laser.

Drawings

FIG. 1 is a schematic view of the epitaxial structure of a DFB laser according to the present invention.

Fig. 2 is a graph of the saturation concentration analysis of Zn atoms in different epitaxial materials.

Fig. 3 is a schematic diagram of epitaxial layer growth according to the present invention.

In the above drawings, an InP substrate 001, an InP epitaxial layer 002, an InGaAs thin layer 101, an AlInAsP insertion layer 102, an AlInAs epitaxial layer 003, an N-AlGaInAs waveguide layer 004, AlGaInAs MQW005, a P-AlGaInAs waveguide layer 006, a P-AlInAs confinement layer 007, a P-InP confinement layer 008, an etching barrier layer 009, an InP connection layer 010, a grating layer 011, an InGaAsP barrier transition layer 012 and an ohmic contact layer 013.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

Please refer to fig. 1 to fig. 3. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.