CN218448910U

CN218448910U - Monolithic integration two-dimensional DFB array chip applied to laser radar

Info

Publication number: CN218448910U
Application number: CN202223277219.5U
Authority: CN
Inventors: 鄢静舟; 季晓明; 缪笛; 吕英豪; 柯程; 薛婷; 杨奕; 吴建忠
Original assignee: Fujian Huixin Laser Technology Co ltd
Current assignee: Fujian Huixin Laser Technology Co ltd
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2023-02-03
Anticipated expiration: 2032-12-07

Abstract

The utility model discloses a monolithic integration two-dimensional DFB array chip applied to laser radar, which relates to the technical field of edge-emitting lasers, and comprises a substrate and a plurality of DFB units arranged above the substrate, wherein each DFB unit comprises a buffer layer and at least two luminous layers vertically stacked above the buffer layer, a separation transition layer is arranged between two adjacent luminous layers, and a metal contact layer is arranged above the luminous layer positioned at the uppermost layer; two side walls of each DFB unit are provided with side gratings and buried layers; and a back electrode is arranged below the substrate, and a front electrode is arranged above the metal contact layer of each DFB unit. The utility model provides a monolithic integration two-dimentional DFB array chip can realize the two-dimentional dot matrix light output of single limit transmission laser instrument chip, can remove light source scanning part from when being applied to laser radar system, helps reducing radar system's complexity, the operation degree of difficulty and manufacturing cost.

Description

Monolithic integration two-dimensional DFB array chip applied to laser radar

Technical Field

The utility model relates to a limit transmission laser technical field, in particular to be applied to laser radar's monolithic integration two dimension DFB array chip.

Background

The laser radar applied to the field of unmanned automobiles draws wide attention to the three-dimensional sensing capability of high detection precision, wide range and high speed. Laser radar can also be applied to fields such as unmanned aerial vehicle, robot simultaneously, and along with artificial intelligence technique's becoming mature day by day, the demand that relevant field was used laser radar sensing is bigger and bigger. The light source selection of the laser radar needs to comprehensively consider factors such as power density, a light source scanning mode and the like, and the light source of the existing laser radar mainly comprises three schemes: 1. GaAs substrate based edge emitting laser scheme; 2. a GaAs substrate based VCSEL scheme; 3. fiber laser solutions.

Among the above 3 schemes, the power density of the edge-emitting laser adopted in scheme 1 can meet the requirement, but because the edge-emitting laser belongs to a point light source, the edge-emitting laser needs to be matched with a scanning component of the light source, which increases the complexity, the operation difficulty and the production cost of the radar system. The VCSEL adopted in the scheme 2 is a surface light source, so that a scanning component can be omitted, but the VCSEL is low in power density, so that the long-distance detection requirement of the laser radar cannot be met; the power density of the optical fiber laser adopted in the scheme 3 can meet the requirement of remote detection, but the optical fiber laser has the problems of high cost and complex process, and also needs to be additionally provided with a scanning component.

Therefore, the above 3 schemes all have disadvantages, and cannot simultaneously meet the comprehensive requirements of the laser radar on various factors such as power density, light source scanning mode and the like. Based on the chip, a monolithically integrated two-dimensional DFB array chip applied to the laser radar is provided.

Disclosure of Invention

The utility model provides a be applied to laser radar's monolithic integration two dimension DFB array chip, the problem that its main aim at exists solves prior art.

The utility model adopts the following technical scheme:

a monolithic integration two-dimensional DFB array chip applied to a laser radar comprises a substrate and a plurality of DFB units arranged above the substrate, wherein each DFB unit comprises a buffer layer and at least two light emitting layers longitudinally stacked above the buffer layer, a separation transition layer is arranged between every two adjacent light emitting layers, and a metal contact layer is arranged above the light emitting layer positioned on the uppermost layer; two side walls of each DFB unit are provided with side gratings and buried layers; and a back electrode is arranged below the substrate, and a front electrode is arranged above the metal contact layer of each DFB unit.

Further, the luminescent layer comprises a lower limiting layer, an active layer MQW and an upper limiting layer from bottom to top; the separation transition layer comprises a tunneling buffer layer, a tunneling layer and a separation layer from bottom to top.

Further, the lasing wavelength of each of the light emitting layers is 1550nm.

Furthermore, the tunneling buffer layer is 1-5 μm thick, the tunneling layer is 20-200nm thick, and the separation layer is 15-60 μm thick.

Further, the distance between each DFB unit is larger than 10 μm; the distance between the light emitting layers in the same DFB cell is also greater than 10 μm.

Furthermore, passivation layers are deposited on two side walls of each DFB unit, and the side gratings are etched on the passivation layers.

Further, the passivation layer comprises a first thin InP layer with the thickness of 10-40nm, an InGaAsP layer with the thickness of 30-120nm and a second thin InP layer with the thickness of 10-15nm.

Further, the buried layer comprises a Fe-doped semi-insulating InP layer and a Si-doped N-type InP layer from bottom to top.

The LED module further comprises a SiNx passivation layer, wherein the SiNx passivation layer covers the upper part of each DFB unit, and an electrode window is arranged for each DFB unit; the front electrode comprises a metal contact electrode, a lead electrode and a pad electrode; each metal contact electrode is arranged between the metal contact layer and the SiNx passivation layer and is connected to the lead electrode and the pad electrode above the SiNx passivation layer through the electrode window.

Furthermore, an insulating layer is arranged above the buried layer between every two adjacent DFB units.

Compared with the prior art, the utility model discloses the beneficial effect who produces lies in:

1. the utility model provides a monolithic integration two-dimentional DFB array chip can realize the two-dimentional dot matrix light output of single limit transmission laser instrument chip, can remove light source scanning part from when being applied to laser radar system, helps reducing radar system's complexity, the operation degree of difficulty and manufacturing cost.

2. The utility model discloses a side grating replaces the plane grating among the prior art to realize steady wavelength output, only needs to carry out once burying technology from this, alright realize accomplishing the preparation of grating part, reduces the number of times of burying of plane grating widely to the greatly reduced technology makes the degree of difficulty.

Drawings

Fig. 1 is a schematic diagram of a complete chip structure of the present invention.

Fig. 2 is a top view of the front electrode of the present invention.

Fig. 3 is a schematic diagram of a part of the chip structure of the present invention.

Fig. 4 is a top view of the side grating of the present invention.

In the figure: 10. a substrate; 11. a buffer layer; 12. a light emitting layer; 121. a lower confinement layer; 122. an active layer MQW; 123. an upper confinement layer; 13. separating the transition layer; 131. tunneling buffer layers; 132. a tunneling layer; 133. a separation layer; 14. a side grating; 15. a passivation layer; 151. a first InP thin layer; 152. a thin InGaAsP layer; 153. a second InP thin layer; 16. burying the layer; 161. a Fe-doped semi-insulating InP layer; 162. an Si-doped N-type InP layer; 17. a metal contact layer; 181. A metal contact electrode; 182. a pad electrode; 183. a lead electrode; 19. a SiNx passivation layer; 20. an insulating layer; 201. deep grooves; 21. and a back electrode.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings. Numerous details are set forth in the following description in order to provide a thorough understanding of the present invention, but it will be apparent to one skilled in the art that the present invention may be practiced without these details.

Referring to fig. 1 to 4, the present invention provides a monolithic two-dimensional DFB array chip for lidar, including a substrate 10 and a plurality of DFB units arranged above the substrate 10, each DFB unit includes a buffer layer 11 and at least two light emitting layers 12 vertically stacked above the buffer layer 11, a separation transition layer 13 is disposed between two adjacent light emitting layers 12, and a metal contact layer 17 is disposed above the light emitting layer 12 on the uppermost layer; two side walls of each DFB unit are provided with side gratings 14 and buried layers 16; a back electrode 21 is provided below the substrate 10, and a front electrode is provided above the metal contact layer 17 of each DFB cell.

Referring to fig. 1 and 3, preferably, the substrate 10 in this embodiment is an InP substrate; the buffer layer 11 is an InP buffer layer; the metal contact layer 17 is a Zn-doped P-type InP layer.

Referring to fig. 1 and 3, specifically, the light-emitting layer 12 includes, from bottom to top, a lower confinement layer 121, an active layer MQW122, and an upper confinement layer 123. Preferably, the lower confinement layer 121 is N-type InGaAsP, the active layer MQW122 is 6 pairs of InGaAsP/InP, and the upper confinement layer 123 is P-type InGaAsP.

Referring to fig. 1 and 3, in particular, the separation transition layer 13 includes a tunneling buffer layer 131, a tunneling layer 132, and a separation layer 133 from bottom to top. The tunneling buffer layer 131 serves as a buffer between the light emitting layer 12 and the tunneling layer 132; the tunneling layer 132 can realize series connection and current conduction of the multiple quantum well layer in the active layer MQW122, thereby generating high gain and reducing the total capacitance; the separating layer 133 serves to separate the spots of the two light-emitting layers 12 away from each other in the far field, thereby ensuring that a lattice light output is achieved. Preferably, the tunneling buffer layer 131 is P-type InP; the separation layer 133 is P-type InP; the tunneling layer 132 includes a P-type heavily doped layer and an N-type heavily doped layer from bottom to top, the P-type heavily doped layer is an InGaAs heavily doped C layer, and the N-type heavily doped layer is an InP heavily doped Si layer.

Referring to fig. 1 to 4, the design concept of the present invention is to realize the two-dimensional lattice light output of a single edge emitting laser chip, thereby satisfying the special light source requirement of the laser radar. Based on this, arranging several DFB units on the substrate 10 can provide basic conditions for the lateral array output of the laser; providing a plurality of light emitting layers 12 within each DFB unit can provide the fundamental conditions for the longitudinal array output of laser light, thereby forming the lattice light required for the laser radar. Preferably, three DFB units are provided in the present embodiment, each DFB unit being provided with three light-emitting layers 12 and two separation transition layers 13.

Referring to fig. 1 to 3, lasers in the 1500-1800nm and 2000-2400nm bands are generally referred to as eye-safe lasers. Compared with 905nm laser, 1550nm laser with the same power has the safety of human eyes which is higher than 10 ten thousand times, meanwhile, the 1500nm laser is just positioned in an 'atmospheric window' in consideration of transmission factors of light waves in the atmosphere, and has excellent performances such as strong smoke penetration capability, high target reflectivity and the like, so that 1550nm is generally accepted as the optimal wavelength of a laser radar light source at present. Based on this, the utility model discloses in every luminescent layer 12's lasing wavelength is 1550nm, consequently this limit transmission laser instrument chip can launch 1550 nm's dot matrix light, and it is higher to have higher people's eye security, accords with the wavelength selection demand of laser radar to the light source.

Referring to fig. 1 and 3, in order to ensure the realization of the lattice light output, the distance between the DFB units should be greater than 10 μm, and the distance between the light emitting layers 12 in the same DFB unit should also be greater than 10 μm. Based on the design requirement that the distance between each DFB unit should be more than 10 μm, the thickness of the tunneling buffer layer 131 is 1-5 μm, the thickness of the tunneling layer 132 is 20-200nm, and the thickness of the separation layer 133 is 15-60 μm.

Referring to fig. 3 and 4, the conventional single longitudinal mode edge emitting laser generally employs a plane grating, and if the vertical multisection epitaxial structure of the present invention employs a plane grating, multiple grating burying processes are required during manufacturing, taking a vertical triple junction as an example, three grating burying processes are required altogether, and in addition, two burying processes of a subsequent BH process are required altogether five times, so that the epitaxial structure is relatively complex and the process difficulty is relatively high. In order to overcome the problem, the utility model discloses a side grating structure realizes steady wavelength output, only needs from this to carry out once burying technology, alright realize accomplishing the preparation of grating part, reduces the number of times of burying of plane grating widely to the greatly reduced technology manufacturing degree of difficulty. Specifically, two side walls of each DFB unit are deposited with passivation layers 15, and the passivation layers 15 are etched with side gratings 14. The passivation layer 15 includes a first InP thin layer 151, an InGaAsP thin layer 152, and a second InP thin layer 153, wherein the first InP thin layer 151 mainly plays a role of passivation and is an etch stop layer of the side grating 14, the InGaAsP thin layer 152 serves as a grating layer, and the second InP thin layer 153 serves as a cap layer of the grating layer. To ensure a reasonable aspect ratio for the side grating 14, the thickness of the first InP thin layer 151 is 10-40nm, the thickness of the ingaasp thin layer 152 is 30-120nm, and the thickness of the second InP thin layer 153 is 10-15nm.

Referring to fig. 1, the present invention adopts a BH burying process, and the buried layer 16 includes, from bottom to top, a Fe-doped semi-insulating InP layer 161 and a Si-doped N-type InP layer 162. The Fe-doped semi-insulating InP layer 161 material can effectively reduce electric leakage, the material is matched with the crystal lattice of the side grating 14, MOCVD can be used for growth in the process, and the process manufacturing difficulty is reduced; while the main role of the Si-doped N-type InP layer 162 is current confinement and guiding, thereby lowering the laser threshold.

Referring to fig. 1 and 2, the monolithic two-dimensional DFB array chip further comprises a SiNx passivation layer 19, a metal contact electrode 181 is disposed above the metal contact layer 14 of each DFB unit, the SiNx passivation layer 19 covers the epitaxial layer on which the metal contact electrode 181 is disposed, and an electrode window is disposed for each metal contact electrode 181; each metal electrode 181 is connected to a lead electrode 182 and a pad electrode 183 above the SiNx passivation layer 19 through an electrode window. The metal contact electrode 181, the lead electrode 182, and the pad electrode 183 constitute the front surface electrode.

Referring to fig. 2, the electrode windows, the lead electrodes 183 and the pad electrodes 182 of two adjacent DFB units are disposed to be shifted from each other, thereby saving the layout space of the front electrodes and ensuring that each DFB unit can be independently controlled.

Referring to fig. 1, in order to ensure electrical leakage, an insulating layer 20 is also disposed over the buried layer 16 between two adjacent DFB units, the insulating layer 20 preferably being a BCB material. During manufacturing, a deep trench 201 is etched between the buried layers 16 of two adjacent DFB units, an insulating layer 20 is coated in the deep trench 201, and finally, the front electrode and the back electrode 21 are manufactured.

The above is only a specific embodiment of the present invention, but the design concept of the present invention is not limited thereto. All utilize the utility model discloses a design concept is right the utility model discloses carry out insubstantial change, all should belong to the infringement the utility model discloses the action of protection scope.

Claims

1. The utility model provides a be applied to laser radar's monolithic integration two-dimentional DFB array chip which characterized in that: the light-emitting diode comprises a substrate and a plurality of DFB units arranged above the substrate, wherein each DFB unit comprises a buffer layer and at least two light-emitting layers longitudinally stacked above the buffer layer, a separation transition layer is arranged between every two adjacent light-emitting layers, and a metal contact layer is arranged above the light-emitting layer positioned on the uppermost layer; two side walls of each DFB unit are provided with side gratings and buried layers; and a back electrode is arranged below the substrate, and a front electrode is arranged above the metal contact layer of each DFB unit.

2. A monolithically integrated two-dimensional DFB array chip for lidar applications as recited in claim 1 wherein: the luminescent layer comprises a lower limiting layer, an active layer MQW and an upper limiting layer from bottom to top; the separation transition layer comprises a tunneling buffer layer, a tunneling layer and a separation layer from bottom to top.

3. The monolithic two-dimensional DFB array chip applied to laser radar as claimed in claim 1, wherein: the lasing wavelength of each light emitting layer is 1550nm.

4. The monolithic two-dimensional DFB array chip applied to laser radar as claimed in claim 2, wherein: the thickness of the tunneling buffer layer is 1-5 mu m, the thickness of the tunneling layer is 20-200nm, and the thickness of the separation layer is 15-60 mu m.

5. The monolithic two-dimensional DFB array chip applied to laser radar as claimed in claim 1, wherein: the distance between each DFB unit is more than 10 μm; the distance between the light emitting layers in the same DFB cell is also greater than 10 μm.

6. The monolithic two-dimensional DFB array chip applied to laser radar as claimed in claim 1, wherein: and two side walls of each DFB unit are deposited with passivation layers, and the side gratings are etched on the passivation layers.

7. The monolithic two-dimensional DFB array chip applied to laser radar as claimed in claim 6, wherein: the passivation layer comprises a first InP thin layer, an InGaAsP thin layer and a second InP thin layer, the thickness of the first InP thin layer is 10-40nm, the thickness of the InGaAsP thin layer is 30-120nm, and the thickness of the second InP thin layer is 10-15nm.

8. The monolithic two-dimensional DFB array chip applied to laser radar as claimed in claim 1, wherein: the buried layer comprises a Fe-doped semi-insulating InP layer and a Si-doped N-type InP layer from bottom to top.

9. The monolithic two-dimensional DFB array chip applied to laser radar as claimed in claim 1, wherein: the silicon-based LED module also comprises a SiNx passivation layer, wherein the SiNx passivation layer covers the upper part of each DFB unit, and an electrode window is arranged for each DFB unit; the front electrode comprises a metal contact electrode, a lead electrode and a pad electrode; each metal contact electrode is arranged between the metal contact layer and the SiNx passivation layer and is connected to the lead electrode and the pad electrode above the SiNx passivation layer through the electrode window.

10. The monolithic two-dimensional DFB array chip applied to laser radar as claimed in claim 1, wherein: and an insulating layer is also arranged above the buried layer between every two adjacent DFB units.