阅读说明：本技术 一种光子晶体面发射激光器及其制作方法 (Photonic crystal surface emitting laser and manufacturing method thereof ) 是由 徐鹏飞 王文知 王岩 罗帅 季海铭 于 2021-08-31 设计创作，主要内容包括：一种光子晶体面发射激光器及其制作方法,在面发射激光器内以n-InP为衬底的半导体叠层的区域外,增加同由InP覆层覆盖的无法导通注入电流的阻流区域。其采用金属有机物化学气相沉积法外延生长有源区及波导结构,结合电子束光刻和干法刻蚀制作光子晶体形成激光外延片,通过常规光刻、氧化和刻蚀工艺制作PCSEL激光芯片；通过增加反向PN结来控制注入电流的范围,通过优化光限制因子来减小PCSEL的阈值电流,从而提高PCSEL的参数特性。本发明通过注入电流在反向pn结中无法导通,只能在中间无反向pn结区域导通,达到控制电流分布的目的,其结构简单,操作方便,注入电流的控制效果好,具有很强的实用性和广泛的适用性。(A photonic crystal surface emitting laser and a manufacturing method thereof are provided, wherein a current-blocking region which is covered by an InP cladding layer and can not conduct injection current is added outside a semiconductor laminated layer region which takes n-InP as a substrate in the surface emitting laser. The method comprises the steps of epitaxially growing an active region and a waveguide structure by adopting a metal organic chemical vapor deposition method, manufacturing photonic crystals by combining electron beam lithography and dry etching to form a laser epitaxial wafer, and manufacturing a PCSEL laser chip by conventional lithography, oxidation and etching processes; the range of the injection current is controlled by increasing the reverse PN junction, and the threshold current of the PCSEL is reduced by optimizing the light limiting factor, so that the parameter characteristic of the PCSEL is improved. The invention achieves the purpose of controlling the current distribution by the fact that the injected current can not be conducted in the reverse pn junction and can only be conducted in the middle without the reverse pn junction region, and has the advantages of simple structure, convenient operation, good control effect of the injected current, strong practicability and wide applicability.)

1. A method for preparing a photonic crystal surface emitting laser is characterized in that a current-blocking region which is covered by an InP covering layer (13) and can not conduct injection current is added outside a semiconductor lamination region taking n-InP (1) as a substrate in the surface emitting laser.

2. The method of claim 1, wherein the current blocking region comprises a reverse pn junction comprising a p-type InP layer (11) and an n-type InP layer (12) grown on an n-InP (1) substrate.

3. The method of producing a photonic crystal surface emitting laser according to claim 1, wherein said semiconductor stack comprises a stack a grown on an n-InP substrate (1), a photonic crystal layer (8);

the stack a includes a strained quantum well active region and waveguide layers on either side thereof.

4. The method of claim 3, wherein an InP pad layer is further grown on both sides of the layer A, and comprises an InP pad layer (6) on the top side and an InP buffer layer (2) on the bottom side.

5. The method of claim 3, wherein the InP cladding layer (13) is covered with a layer B on top, comprising a protective layer (14), a contact layer (15), and an insulating layer (16).

6. A photonic crystal surface-emitting laser produced by the production method according to any one of claims 1 to 5, comprising a semiconductor stack disposed in a vertical cavity between an n-InP substrate (1) and an InP cladding layer (13), an inverted pn junction being disposed outside the vertical cavity;

a lamination B composed of a protective layer (14), a contact layer (15) and an insulating layer (16) covers the top surface of the InP covering layer (13);

the p-surface electrode (17) is arranged in a p-surface electrode window formed in the insulating layer (16), and the n-surface electrode (18) is arranged on the bottom surface of the n-InP substrate (1);

the semiconductor stack comprises a stack A, a photonic crystal layer (8); the lamination A comprises a strain quantum well active region and waveguide layers on two sides of the strain quantum well active region;

the reverse pn junction includes an n-type InP layer (12) on a p-type InP layer.

7. The photonic crystal surface-emitting laser according to claim 6, wherein said layer stack A is provided with an InP spacer layer (6) on the top side and an InP buffer layer (2) on the bottom side.

8. The method for preparing a photonic crystal surface emitting laser according to claim 6, comprising the steps of:

s1, sequentially epitaxially growing an InP buffer layer (2), an AlGaInAs lower waveguide layer (3), a strained quantum well active region (4), an AlGaInAs upper waveguide layer (5), an InP gasket layer (6) and an InGaAsP grating layer (7) on an n-InP substrate (1);

s2, manufacturing a photonic crystal layer (8) in the InGaAsP grating layer (7);

s3, after the inner layer (9) is covered by the epitaxial InP on the photonic crystal layer, an oxygen silicon hard mask (10) is grown;

s4, defining a semiconductor lamination area by photoetching, and etching off the oxygen silicon hard mask outside the area;

s5, etching away the material growing outside the semiconductor laminated layer area until reaching the substrate;

s6, sequentially growing p-type InP (11) and n-type InP (12) outside the semiconductor laminated layer area to form a reverse pn junction;

s7, removing the residual oxygen silicon hard mask (10), the epitaxial InP covering layer (13), the upper protective layer (14) and the InGaAs contact layer (15);

s8, growing silicon dioxide on the epitaxial wafer to form an insulating layer (16);

and S9, opening an electrode window on the insulating layer, depositing metal in the electrode window to form a p-surface electrode (17), thinning the n-InP substrate (1), and depositing metal to form an n-surface electrode (18).

9. The method for fabricating a photonic crystal surface emitting laser according to claim 8, wherein the photonic crystal layer (8) is fabricated in the InGaAsP grating layer (7) by using electron beam exposure and dry etching in step S2.

10. The method of claim 8, wherein the step S5 is performed by etching the growth material outside the semiconductor stacked region to the substrate by a wet-dry semiconductor process.

Technical Field

The invention relates to a manufacturing method of a laser, in particular to a photonic crystal surface emitting laser and a manufacturing method thereof, and relates to the technical field of single-mode high-power semiconductor laser chips.

Background

Edge-emitting lasers (EELs) can be used in a wide range of applications due to the wide choice of material systems to achieve lasing over a wide range of wavelengths. However, since the cleavage cavity surface needs to be formed in the manufacturing process, the on-chip detection cannot be compatible, so that the manufacturing cost is high and the cavity surface is easily damaged.

The Vertical Cavity Surface Emitting Laser (VCSEL) is compatible with a wafer process, and is low in manufacturing cost and good in reliability. But due to the material system characteristics, VCSELs have limited lasing wavelengths and relatively low power. Furthermore, neither the EEL with the grating nor the VCSEL can achieve a single mode beam of watts.

The Photonic Crystal Surface Emitting Laser (PCSEL) is a brand-new semiconductor laser type, combines the advantages of the EEL and the VCSEL, can realize the wide wavelength coverage range and high power of the EEL, and has a low-cost process similar to the VCSEL. In addition, due to the unique photon limiting characteristic, by increasing the gain area of the active region, the PCSEL can realize a watt-level single-mode light beam, and becomes an ideal laser light source in the future.

The PCSEL laser reported at present has large threshold value, and the main reason is that besides the large light absorption caused by the material defect of the photonic crystal, the injected current distribution and the optical field can not be overlapped in space well, so that the light restriction factor is small.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a method for manufacturing a photonic crystal surface-emitting laser.

In order to achieve the above object, the present invention adopts the following technical solutions:

a method for preparing a photonic crystal surface emitting laser comprises adding a current-blocking region which is covered by an InP covering layer and can not conduct injection current outside a semiconductor laminated region with n-InP as a substrate in the surface emitting laser.

The current blocking region comprises a reverse pn junction comprising a p-type InP layer and an n-type InP layer grown on an n-InP substrate.

The semiconductor laminate comprises a laminate A grown on an n-InP substrate, a photonic crystal layer and an InP cladding inner layer; the stack a includes a strained quantum well active region and waveguide layers on either side thereof.

Further, an InP pad layer is also grown on both sides of the above-mentioned stack a, including an InP pad layer on the top side and an InP buffer layer on the bottom side.

Further, a laminate B including a protective layer, a contact layer, and an insulating layer is provided on top of the InP cladding layer (13).

A photonic crystal surface emitting laser is prepared according to the preparation method, and comprises a semiconductor lamination layer arranged in a vertical cavity between an n-InP substrate and an InP covering layer, and a reverse pn junction arranged outside the vertical cavity;

a lamination B consisting of a protective layer, a contact layer and an insulating layer covers the top surface of the InP covering layer;

the p-surface electrode is arranged in a p-surface electrode window formed in the insulating layer, and the n-surface electrode is arranged on the bottom surface of the n-InP substrate;

the semiconductor laminate includes a laminate A, a photonic crystal layer, and an InP cladding inner layer; stack a includes a strained quantum well active region and waveguide layers on either side thereof.

The reverse pn junction includes an n-type InP layer (12) on a p-type InP layer.

The InP spacer layer is provided on the top side of stack a and the InP buffer layer is provided on the bottom side of stack a.

The preparation method of the photonic crystal surface emitting laser comprises the following steps:

s1, sequentially epitaxially growing an InP buffer layer, an AlGaInAs lower waveguide layer, a strained quantum well active region, an AlGaInAs upper waveguide layer, an InP gasket layer and an InGaAsP grating layer on an n-InP substrate;

s2, manufacturing a photonic crystal layer (8) in the InGaAsP grating layer (7);

s3, after the inner layer is covered by the epitaxial InP on the photonic crystal layer, an oxygen silicon hard mask is grown;

s4, defining a semiconductor lamination area by photoetching, and etching off the oxygen silicon hard mask outside the area;

s5, etching away the material growing outside the semiconductor laminated layer area until reaching the substrate;

s6, sequentially growing p-type InP and n-type InP outside the semiconductor laminated region to form a reverse pn junction;

s7, removing the residual oxygen-silicon hard mask, extending the InP covering layer, the upper protective layer and the InGaAs contact layer;

s8, growing silicon dioxide on the epitaxial wafer to be used as an insulating layer;

and S9, opening an electrode window on the insulating layer, depositing metal in the electrode window to form a p-side electrode, thinning the n-InP substrate, and depositing metal to form an n-side electrode.

In the step S2, a photonic crystal layer is fabricated in the InGaAsP grating layer by using electron beam exposure and dry etching; in step S5, the growth material outside the semiconductor stacked region is etched to the substrate by using a wet-dry bonding semiconductor process.

The invention has the advantages that:

a photonic crystal surface emitting laser and a manufacturing method thereof are disclosed, wherein a metal organic chemical vapor deposition method is adopted to epitaxially grow an active region and a waveguide structure, electron beam lithography and dry etching are combined to manufacture a photonic crystal to form a laser epitaxial wafer, and a PCSEL laser chip is manufactured through conventional lithography, oxidation and etching processes; the range of the injection current is controlled by increasing the reverse PN junction, and the threshold current of the PCSEL is reduced by optimizing the light limiting factor, so that the parameter characteristic of the PCSEL is improved.

The PCSEL can not be conducted in the reverse pn junction through the injection current, and can only be conducted in the middle non-reverse pn junction region, so that the aim of controlling current distribution is fulfilled.

Drawings

Fig. 1 is a schematic structural diagram of a grating layer-based semiconductor stack.

Fig. 2 is a schematic structural diagram of etching a grating layer.

FIG. 3 is a schematic diagram of the structure of the photonic crystal epitaxial InP covered with the inner layer.

Fig. 4 is a schematic structural diagram of the etched semiconductor stack.

Fig. 5 is a schematic diagram of a structure for growing a reverse pn junction.

FIG. 6 is a scanning electron micrograph of a growing reverse pn junction.

Fig. 7 is a schematic diagram of the structure after the InP capping layer is epitaxial.

Fig. 8 is a schematic structural view of a photonic crystal surface-emitting laser.

The designations in the drawings have the following meanings: 1. the photonic crystal structure comprises an n-InP substrate, 2, an InP buffer layer, 3, a lower waveguide layer, 4, a strained quantum well active region, 5, an upper waveguide layer, 6, an InP gasket layer, 7, a grating layer, 8, a photonic crystal, 9, an InP covering inner layer, 10, an oxygen silicon hard mask, 11, p-type InP, 12, n-type InP, 13, an InP covering layer, 14, a protective layer, 15, a contact layer, 16, an oxygen silicon insulating layer, 17, a p-surface electrode, 18 and an n-surface electrode.

Detailed Description

The invention is described in detail below with reference to the figures and the embodiments.

A Photonic Crystal Surface Emitting Laser is a regrown PCSEC (Photonic Crystal Surface Emitting Laser), and the structure of the Photonic Crystal Surface Emitting Laser comprises an n-InP substrate 1, a semiconductor lamination layer, a reverse pn junction, an InP covering layer 13, a lamination B, a p-Surface electrode 17 and an n-Surface electrode 18.

As shown in fig. 8, the semiconductor stack grown on the n-InP substrate constitutes an injection current region, and the reverse pn junction is grown outside the semiconductor stack on the n-InP substrate, that is, outside the injection current region, a current blocking region that cannot conduct injection current is formed. An InP cladding layer overlies the top surfaces of the semiconductor stack and the reverse pn junction. The reverse pn junction consists of an n-type InP layer 12 overlying a p-type InP layer 11.

The layer B covers the top surface of the InP covering layer and is composed of a protective layer, a contact layer and an insulating layer which are sequentially stacked. The insulating layer is provided with an electrode window, the p-surface electrode is arranged in the electrode window, and the n-surface electrode is arranged on the bottom surface of the n-InP substrate.

The semiconductor lamination comprises an InP buffer layer 2, a lower waveguide layer, a strain quantum well active region 4, an upper waveguide layer, an InP gasket layer 6, a photonic crystal layer 8 and an InP covering inner layer 9 which are sequentially laminated.

The InP cladding inner layer plays a role in protecting the photonic crystal layer in the process of reverse pn junction, and is convenient for growing the oxygen silicon hard mask.

The material of the upper and lower waveguide layers is preferably AlGaInAs.

The master diffraction grating of the photonic crystal layer is preferably InGaAsP.

The material of the n-side electrode is preferably metal such as Au, including Au, AuGe/Au.

The p-side electrode is preferably made of metal such as Au, Ti, Pt, or Cr.

Specifically, the material parameters of the semiconductor stack (region where current is injected) in the PCSEL, including the selection of specific materials and the thickness of each layer, are defined according to the required performance parameters.

A preparation method of a photonic crystal surface emitting laser comprises the following steps:

s1, epitaxially growing an InP buffer layer, an AlGaInAs lower waveguide layer 3, a strained quantum well active region 4, an AlGaInAs upper waveguide layer 5, an InP spacer layer 6, and an InGaAsP grating layer 7 on an n-InP substrate in sequence, as shown in fig. 1.

S2, as shown in fig. 2, a photonic crystal is fabricated in the InGaAsP grating layer by electron beam exposure and dry etching.

S3, as shown in fig. 3, after the InP cap inner layer is epitaxially grown on the photonic crystal layer, the oxygen silicon hard mask 10 is grown.

S4, defining the injection current (semiconductor lamination) area by photolithography, and etching off the oxygen silicon hard mask outside the area.

S5, etching away the material grown outside the current injection region to the substrate by using the semiconductor process of dry-wet combination, as shown in fig. 4.

S6, p-type InP and n-type InP are sequentially grown outside the current injection region to form an inverted pn junction, as shown in fig. 5.

S7, the remaining oxygen silicon hard mask is removed, the InP capping layer is epitaxial, and the upper clad protective layer 14 and InGaAs contact layer 15 are formed, as shown in fig. 7.

S8, growing silicon dioxide on the epitaxial wafer to be used as an insulating layer.

S9, opening an electrode window on the insulating layer, depositing metal in the electrode window to form a p-side electrode, thinning the n-InP substrate, and depositing metal to form an n-side electrode, as shown in fig. 8.

FIG. 6 shows a scanning electron micrograph of a grown reverse pn junction.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.