阅读说明：本技术 一种高性能dfb激光器结构及其生长方法 (High-performance DFB laser structure and growth method thereof ) 是由 单智发 张永 陈阳华 姜伟 方天足 于 2020-04-20 设计创作，主要内容包括：一种高性能DFB激光器结构,包括InP基底,在所述InP基底上从下而上依次采用MOCVD沉积的N-InP缓冲层、N-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、光栅层、InGaAsP势垒过度层、InGaAs欧姆接触层；在所述N-InP缓冲层与所述N-AlInAs外延层中间插入一层N-InAlAsP；本方案设计的一种高性能DFB激光器结构,在N-InP缓冲层与N-InAlAs外延层中间插入一层N-InAlAsP,可以获得高制量的MQW,提高激光器的可靠性,同时还能平滑N-InP缓冲层与N-InAlAs外延层之间的导带能阶差,减小DFB激光器的电阻,提高DFB激光器的性能。(A high-performance DFB laser structure comprises an InP substrate, wherein an N-InP buffer layer, an N-AlInAs epitaxial layer, an N-AlGaInAs waveguide layer, AlGaInAs MQW, a P-AlGaInAs waveguide layer, a P-AlInAs limiting layer, a P-InP limiting layer, a grating layer, an InGaAsP barrier transition layer and an InGaAs ohmic contact layer which are deposited on the InP substrate from bottom to top in sequence by MOCVD; inserting a layer of N-InAlAsP between the N-InP buffer layer and the N-AlInAs epitaxial layer; according to the high-performance DFB laser structure designed by the scheme, the layer of N-InAlAsP is inserted between the N-InP buffer layer and the N-InAlAs epitaxial layer, so that a high-yield MQW can be obtained, the reliability of the laser is improved, the conduction band energy step difference between the N-InP buffer layer and the N-InAlAs epitaxial layer can be smoothed, the resistance of the DFB laser is reduced, and the performance of the DFB laser is improved.)

1. A high-performance DFB laser structure comprises an InP substrate, wherein an N-InP buffer layer, an N-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 from bottom to top in sequence by adopting MOCVD; the method is characterized in that: and inserting a layer of N-InAlAsP between the N-InP buffer layer and the N-AlInAs epitaxial layer.

2. A high performance DFB laser structure according to claim 1 wherein: the N-InAlAsP material is expressed by (Al0.48In0.52As) X (InP) (1-X), wherein X represents the proportion of the Al0.48In0.52As material in the AlInAsP material, and the value is between 0.5 and 0.99.

3. A high performance DFB laser structure according to claim 2, wherein: the Al0.48In0.52As material is lattice matched to InP.

4. A high performance DFB laser structure according to claim 1 wherein: the N-InAlAsP material is grown by MOCVD.

5. A high performance DFB laser structure according to claim 1 wherein: the conductivity of the InP substrate is 2-8x10¹⁸cm^-2。

6. A preparation method of a high-performance DFB laser is characterized by comprising the following steps: which comprises the following steps:

the method comprises the following steps: with the conductivity of 2-8x10¹⁸cm^-2The InP is used as a growth substrate and 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, trimethyl indium, trimethyl gallium, trimethyl aluminum, diethyl zinc, silane, arsine, phosphine and the like are used as reaction source gases, an N-InP buffer layer is grown firstly, the flow rate of trimethyl indium is 300sccm, and the flow rate of phosphine is 1800 sccm;

step two: after the growth of the N-InP buffer layer is finished, closing the trimethylindium and the silane, introducing arsine, wherein the flow of the arsine is 600 sccm, and simultaneously reducing the flow of the phosphine; after 3 minutes, introducing trimethyl indium and silane, and starting to grow an N-AlInAsP epitaxial layer;

step three: on the basis of the second step, the Source flow rate of the trimethyl indium is 100sccm, the phosphane is closed after 200 seconds,

continuously increasing the flow of trimethyl aluminum, trimethyl indium and silane, and starting to grow an N-AlInAs epitaxial layer; then growing an N-AlGaInAs waveguide layer, an AlGaInAs MQW, a P-AlGaInAs waveguide layer, a P-AlInAs limiting layer and a P-InP limiting layer in sequence, and manufacturing a grating;

step four: and finally, growing an InP connecting layer, an InGaAsP barrier transition layer and an InGaAs ohmic contact layer by adopting a pulse deposition method.

7. A method for preparing a high performance DFB laser according to claim 6, wherein: in the second step, the flow rate of the phosphane is reduced, specifically, the flow rate of the phosphane is reduced to 300 sccm.

8. A method for preparing a high performance DFB laser according to claim 6, wherein: the Source flows of trimethylaluminum, trimethylindium and silane are continuously increased as described in step three, in a manner which increases the flows in particular linearly.

Technical Field

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

Background

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 a preferred light source, the DFB adopts grating modulation with periodically changed 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 time delay.

Meanwhile, the working wavelength of the DFB laser applied to the 5G mobile communication system is 1200-1600 nm, the working temperature is-40-90 ℃, the modulation rate is 10 Gb/s-56 Gb/s, and the difficulty of AlGaInAs series materials on an InP substrate through MOCVD equipment is higher 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) atomic nonlinear mixing can exist in the As-P switching interface; (4) when the N-InP and the N-InAlAs epitaxial layers are close to each other, a heterogeneous band step is formed, the transmission of current carriers is influenced, the parasitic resistance of the DFB laser is increased, and the performance of the device is influenced.

Therefore, the scheme provides a DFB laser structure, and the N-InAlAsP epitaxial layer is inserted between the N-InP layer and the N-InAlAs layer, so that on one hand, high-yield MQW can be obtained, and the reliability of the laser is improved; on the other hand, the conduction band energy step difference between the N-InP epitaxial layer and the N-InAlAs epitaxial layer can be smoothed, the resistance of the DFB laser is reduced, and the performance of the DFB laser is improved; thereby effectively solving the technical problems.

Disclosure of Invention

To overcome the above-mentioned deficiencies in the prior art, it is an object of the present invention to provide a high performance DFB laser structure.

In order to achieve the above objects and other related objects, the present invention provides the following technical solutions: a high-performance DFB laser structure comprises an InP substrate, wherein an N-InP buffer layer, an N-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 from bottom to top in sequence by adopting MOCVD; the method is characterized in that: and inserting a layer of N-InAlAsP between the N-InP buffer layer and the N-AlInAs epitaxial layer.

Preferably, the N-InAlAsP material is expressed by (Al0.48In0.52As) X (InP) (1-X), wherein X represents the proportion of Al0.48In0.52As material in the AlInAsP material, and the value is between 0.5 and 0.99.

Preferably, the Al0.48In0.52As material is lattice matched to InP.

Preferably, the N-InAlAsP material is grown by MOCVD.

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

The invention also discloses a preparation method of the high-performance DFB laser, which comprises the following steps:

the method comprises the following steps: with the conductivity of 2-8x10¹⁸cm^-2The InP is used as a growth substrate and 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, trimethyl gallium and trimethyl gallium are used as carrier gasUsing methyl aluminum, diethyl zinc, silane, arsine, phosphane and the like as reaction source gases, firstly growing an N-InP buffer layer, wherein the flow rate of trimethyl indium is 300sccm, and the flow rate of phosphane is 1800 sccm;

step two: after the growth of the N-InP buffer layer is finished, closing the trimethylindium and the silane, introducing arsine, wherein the flow of the arsine is 600 sccm, and simultaneously reducing the flow of the phosphine; after 3 minutes, introducing trimethyl indium and silane, and starting to grow an N-AlInAsP epitaxial layer;

step three: on the basis of the second step, the Source flow rate of the trimethyl indium is 100sccm, the phosphane is closed after 200 seconds,

continuously increasing the Source flow of trimethyl aluminum, trimethyl indium and silane, and starting to grow an N-AlInAs epitaxial layer; then growing an N-AlGaInAs waveguide layer, an AlGaInAs MQW, a P-AlGaInAs waveguide layer, a P-AlInAs limiting layer and a P-InP limiting layer in sequence, and manufacturing a grating;

step four: and finally, growing an InP connecting layer, an InGaAsP barrier transition layer and an InGaAs ohmic contact layer by adopting a pulse deposition method.

Preferably, the flow rate of the phosphane in the step two is reduced, specifically the flow rate of the phosphane is reduced to 300 sccm.

Preferably, the Source flow rates of trimethylaluminum, trimethylindium and silane are continuously increased in step three in a manner that increases the flow rates, in particular linearly.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

on the basis of the traditional DFB laser structure, the invention provides a new DFB laser structure, namely a layer of N-InAlAsP is inserted between an N-InP buffer layer and an N-InAlAs epitaxial layer, so that on one hand, high-yield MQW can be obtained, and the reliability of the laser is improved; on the other hand, the conduction band energy step difference between the N-InP epitaxial layer and the N-InAlAs epitaxial layer can be smoothed, the resistance of the DFB laser is reduced, and the performance of the DFB laser is improved.

Drawings

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

FIG. 2 is a schematic diagram of the energy band structure of a DFB laser according to the present invention.

FIG. 3 is a schematic diagram of the growth of an AlInAsP epitaxial layer according to the invention.

In the above drawings, an InP substrate 001, an N-InP buffer layer 002, an N-AlInAsP insertion layer 101, an N-AlInAs epitaxial layer 003, an N-AlGaInAs waveguide layer 004, AlGaInAs MQW 005, a P-AlGaInAs waveguide layer 006, a P-AlInAs confinement layer 007, a P-InP confinement layer 008, an etch stop layer 009, an InP connection layer 010, a grating layer 011, an InGaAsP barrier transition layer 012 and an InGaAs 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.