CN111404028A

CN111404028A - Laser device based on wide-spectrum epitaxial growth structure

Info

Publication number: CN111404028A
Application number: CN202010240814.8A
Authority: CN
Inventors: 马丽
Original assignee: Beijing Spectrum Technology Co ltd
Current assignee: Beijing Spectrum Technology Co ltd
Priority date: 2020-03-31
Filing date: 2020-03-31
Publication date: 2020-07-10

Abstract

The invention discloses a laser device based on a wide-spectrum epitaxial growth structure, wherein the epitaxial growth structure of the laser device comprises an upper limiting layer, an active region and a lower limiting layer, the upper limiting layer, the active region and the active region are sequentially arranged in an overlapping contact manner, the active region comprises N quantum well layers and N +1 quantum barrier layers, N is more than or equal to 1 and less than or equal to 10, the N +1 quantum barrier layers and the N quantum well layers are sequentially arranged in a contact manner at intervals, the N quantum well layers are compressive strain structures, the N +1 quantum barrier layers are tensile strain structures, the N quantum well layers adopt 1% -1.2% of compressive strain structures, the N +1 quantum barrier layers adopt 0.2% -0.3% of tensile strain structures, and by introducing a multiple quantum well pair with asymmetric strain thickness and strain in an epitaxial manner in the active region of the laser device, the purpose of widening a P L spectrum is achieved by adjusting a material energy band structure through an asymmetric structure, the laser device can have a wide temperature working range and have a wide working spectrum without additional process step and structural design, and the laser device cost can be saved.

Description

Laser device based on wide-spectrum epitaxial growth structure

Technical Field

The invention relates to the technical field of laser equipment, in particular to a laser device based on a wide-spectrum epitaxial growth structure.

Background

With the advent of the information society, the loading, transmission, exchange, processing, and storage of high-rate information streams has become a key technology, and semiconductor optoelectronic technology is one of the pillars of these core technologies, and semiconductor optoelectronic devices, particularly semiconductor lasers, are in the heart position of these core technologies. Semiconductor lasers, also known as laser diodes, are lasers that use semiconductor materials as the working substance. The semiconductor laser covers the widest wave band range, and by selecting different semiconductor laser active materials or changing the components of each component of the multi-component compound semiconductor, the laser wavelength with a wide range can be obtained to meet different requirements.

When the size of the material is reduced to the nanometer level, not only the size is greatly miniaturized, but also some quantum effects such as surface interface effect and the like are particularly remarkable, and the appearance of the characteristics can be applied to the aspects of improvement of electronic elements, increase of sensitivity and the like. More specifically, it is known from quantum mechanical wave particle duality that since electrons have particle properties and wave properties, the wave function length of electrons in a nanomaterial is close to the characteristic dimension of a quantum structure, and the wave properties of electrons are sufficiently exhibited at this time. Therefore, when a material is reduced to a few nanometers in one direction, quantum confinement effect occurs in the direction, and electrons are confined in a two-dimensional space formed by the other two dimensions and move freely, so that the system becomes a quantum well (quantum well). The quantum well can use a semiconductor layer with a higher energy gap as an energy barrier layer, a semiconductor with a lower energy gap as an energy well layer, and the energy barrier layer clamps the energy well layer from two sides to form the quantum well with a trap-shaped energy band structure, so that a carrier is easily limited to increase the light emitting efficiency.

The semiconductor laser generates laser light with three necessary design factors, namely meeting the population inversion, the resonant cavity design and the threshold gain. An important feature of semiconductor laser structures is that the stimulated emission is confined in the active region, which is achieved by selecting the materials forming the PN junction and the active region structure, the higher the confinement efficiency of carriers and light, the higher the efficiency of the semiconductor laser. The PN junction can be classified into a homojunction, a single heterojunction, and a quantum well structure according to the material and structure of the PN junction. The quantum well semiconductor laser generally makes the active thickness of the double heterojunction laser into a structure below tens of nanometers, that is, in the semiconductor double heterojunction, the narrow band gap of the intermediate interlayer is as thin as compared with the de broglie wavelength or the electron mean free path magnitude of electrons in the semiconductor, and at this time, the carriers, that is, electrons and holes, are limited in a certain region to form a quantum well structure. The quantum well structure consists of one or several very thin layers of narrow bandgap semiconductor alternating with layers of wide bandgap semiconductor. The quantum well can restrain the carrier in a very small area effectively, and the quantum well laser reduces the number of the carrier needed for realizing the population inversion, so the threshold current is greatly reduced. The quantum well structure is a typical structure of most high-performance semiconductor optoelectronic devices, and the multiple quantum well structure is widely applied to DFB (distributed feedback) lasers, so that the performance of the lasers is greatly improved, mainly represented by reducing threshold current and power consumption, and particularly the temperature characteristic of the laser in working can be improved.

In production practice, one problem that plagues laser manufacturers is: users hope to use the laser in a wider temperature range, such as the temperature range of-40-70 ℃ in the field, the laser is required to realize stable operation, and the laser has a wider operating spectrum to expand the application range. Therefore, how to fully utilize the structure of the quantum well is a technical problem which needs to be solved urgently, and how to realize that the semiconductor laser can stably work in a wide temperature range and has a wider working spectrum to expand the application range of the semiconductor laser by adjusting the energy band structure of the semiconductor material.

Disclosure of Invention

The invention aims to provide a laser device based on a wide-spectrum epitaxial growth structure, which aims to solve the problems in the prior art, can ensure that a semiconductor laser stably works in a wide temperature range and has a wider working spectrum.

In order to achieve the purpose, the invention provides the following scheme: the invention provides a laser device based on a wide-spectrum epitaxial growth structure, which comprises the following specific contents:

a laser device based on a wide-spectrum epitaxial growth structure, wherein an epitaxial layer structure of the laser device comprises an upper limiting layer, an active region and a lower limiting layer, wherein the upper limiting layer, the active region and the lower limiting layer are sequentially arranged in an overlapping contact manner, the active region comprises N quantum well layers and N +1 quantum barrier layers, and N is larger than or equal to 1 and smaller than or equal to 10;

the N +1 quantum barrier layer and the N quantum well layer are sequentially arranged in contact at intervals;

the N quantum well layers are compressive strain structures;

the N +1 quantum barrier layer is of a tensile strain structure.

Preferably, the N quantum well layer employs a compressive strain structure in a range of 1% to 1.2%.

Preferably, the N +1 quantum barrier layer adopts a tensile strain structure in the range of 0.2% -0.3%.

Preferably, the N +1 quantum barrier layers have the same thickness, and the N quantum well layers have different thicknesses.

Preferably, the N +1 quantum barrier layer and the N quantum well layer are within ± 2% of a design thickness when processed.

The invention discloses the technical effects that the invention provides a laser device based on a wide-spectrum epitaxial growth structure, from the viewpoint that the laser epitaxial structure has important influence on the spectrum width of a laser active region P L, the step-shaped energy band of a quantum well allows injected carriers to be filled step by step according to the energy band of the quantum well, so that the energy quantization of the injected carriers is realized, the utilization rate of the carriers injected into the active region is improved, the energy band structure of a semiconductor material can be adjusted by fully utilizing the structure of the quantum well, the energy band structure of the material is adjusted through an asymmetric structure by introducing a multi-quantum well pair with asymmetric thickness and strain in the extension of the active region of the laser, the purpose of widening the P L spectrum is achieved, the wide-temperature-range work of the laser device can be realized, the working spectrum is wide, the wavelength tuning range is wide, the coupling with an optical fiber is easy, extra process steps and structure design are not needed, and the research and development cost of the laser device can be saved.

Meanwhile, the limited quality of a hole is reduced by introducing compressive strain into the quantum well, the transition between valence bands is further reduced, so that the threshold current of the quantum well laser is greatly reduced, the quantum effect and the oscillation frequency are greatly improved, the temperature characteristic is further improved due to the reduction of the transition between the valence bands and the reduction of Auger recombination, the laser can work without refrigeration, and strain (compressive strain/tensile strain) is introduced into the well and the barrier, so that the material quality can be improved, the service life of the laser is prolonged, and the characteristics that the compressive strain corresponds to a TE mode and the tensile strain mainly corresponds to a TM mode can be utilized, so that the laser device disclosed by the invention is high in integration degree.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic diagram of a DFB laser;

fig. 2 is a schematic diagram of the structure of the active region of the laser device of the present invention.

Wherein, 1 is the injection current, 2 is the AR film, 3 is the output light, 4 is the active area, 5 is the grating.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 1-2, the present invention provides a laser device based on a wide-spectrum epitaxial growth structure, and the technical concept of this embodiment will be described first, the spectral width of the photoluminescence spectrum (P L spectrum) of the active region of a quantum well laser has a large relationship with the epitaxial structure of the active region, the present invention provides a wide-spectrum laser device based on an asymmetric quantum well epitaxial structure, that is, the energy band structure of the active region of a semiconductor laser is changed by adjusting the thickness and strain of the epitaxial material of the active region of the laser, so as to realize a semiconductor laser device with wide spectrum and wide temperature operation, fig. 1 is a schematic structural diagram of a DFB laser, where 1 is an injection current, 2 is an AR film, 3 is output light, 4 is an active region, and 5 is a grating.

In this embodiment, for a laser device based on a wide-spectrum epitaxial growth structure, an epitaxial layer structure of the laser device includes an upper confinement layer, an active region 4, and a lower confinement layer. The upper limiting layer and the lower limiting layer of this embodiment adopt a mature design scheme of the prior art, the upper limiting layer, the active region 4 and the lower limiting layer are sequentially arranged in an overlapping contact manner, the active region 4 is mainly improved, an active region structure of the laser device is shown in fig. 2, an epitaxial structure of the active region 4 includes seven quantum barrier layers and six quantum well layers, the seven quantum barrier layers are respectively a first quantum barrier layer, a second quantum barrier layer, a third quantum barrier layer, a fourth quantum barrier layer, a fifth quantum barrier layer, a sixth quantum barrier layer and a seventh quantum barrier layer, the six quantum well layers are respectively a first quantum well layer, a second quantum well layer, a third quantum well layer, a fourth quantum well layer, a fifth quantum well layer and a sixth quantum well layer, and the six quantum well layers and the seven quantum barrier layers are sequentially arranged in an overlapping contact manner. As shown in fig. 2, the thicknesses of the six quantum well layers are different, from top to bottom, the thicknesses of the first quantum well layer to the sixth quantum well layer are respectively 8nm, 6nm and 5nm, and the thicknesses of the seven quantum barrier layers are the same and are all 10 nm. Because the epitaxial layer growth structure of the active region 4 is very sensitive to the thickness and the size of the amount of the quantum well, during specific processing, the error of the actual quantum well thickness deviating from the designed thickness is within plus or minus 2%, the ideal deviation value is plus or minus 1%, and the designed lasing wavelength value of the final laser device when working at room temperature is 1550 nm.

According to a further optimized scheme, the six quantum well layers are all of a compressive strain structure, the magnitude of compressive strain is 1.2%, the first quantum well layer, the second quantum well layer and the third quantum well layer are made of the same semiconductor material, the fourth quantum well layer is made of another semiconductor material, the fifth quantum well layer and the sixth quantum well layer are made of another semiconductor material different from the former semiconductor material, the P L spectrum wavelengths of the three semiconductor materials are 1570nm, 1530nm and 1500nm respectively, the seven quantum barrier layers are all of tensile strain structures, the magnitude of tensile strain is 0.3%, and the P L spectrum wavelength is 1.10 mu m.

In the laser device of the embodiment, the active region is designed into a plurality of quantum well and quantum barrier pairs with asymmetric thickness and asymmetric strain, the active region material energy band structure is adjusted by introducing an asymmetric structure, the aim of widening the P L spectrum width is achieved by using the epitaxial material thickness and strain adjustment of the active region of the laser device, the wide temperature range operation of the laser device can be realized, the laser device has a wider operating spectrum, the wavelength tuning range can be wider, the laser device is easy to couple with an optical fiber, no additional process step and structure design are needed, and the research and development cost of the laser device can be saved.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. A laser device based on a wide-spectrum epitaxial growth structure, wherein an epitaxial layer structure of the laser device comprises an upper limiting layer, an active region and a lower limiting layer, wherein the upper limiting layer, the active region and the lower limiting layer are sequentially arranged in an overlapping contact manner, the active region comprises N quantum well layers and N +1 quantum barrier layers, and N is larger than or equal to 1 and smaller than or equal to 10;

the N quantum well layers are compressive strain structures;

the N +1 quantum barrier layer is of a tensile strain structure.

2. The broad spectrum epitaxial growth structure-based laser device of claim 1 wherein the N quantum well layers employ a compressively strained structure in the range of 1% -1.2%.

3. The broad spectrum epitaxial growth structure based laser device of claim 1, wherein the N +1 quantum barrier layer employs a tensile strained structure in the range of 0.2% -0.3%.

4. The laser device based on the wide-spectrum epitaxial growth structure of claim 1, wherein the N +1 quantum barrier layers are the same thickness, and the N quantum well layers are different thicknesses.

5. The laser device according to claim 4, wherein the N +1 quantum barrier layer and the N quantum well layer are within ± 2% of a design thickness during processing.