CN111106506A

CN111106506A - Silicon-based nanolaser based on surface plasmon and its preparation method

Info

Publication number: CN111106506A
Application number: CN201911257016.XA
Authority: CN
Inventors: 李梦珂; 杨琳; 陈利; 李韦烨; 马刘红; 钟英辉; 段智勇
Original assignee: Zhengzhou University
Current assignee: Zhengzhou University
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2020-05-05

Abstract

本发明涉及一种基于表面等离激元的硅基纳米激光器的制备方法：在硅衬底上生长SiO₂基层；采用ICP干法刻蚀和HF湿法腐蚀相结合的方法在SiO₂层上沿着Si衬底的<110>方向刻蚀出多个沟槽；分别用HF溶液和去离子水清洗，除去沟槽底部剩余的SiO₂基层，露出硅衬底；采用KOH溶液，在沟槽底部向硅衬底延伸腐蚀出开口向上的V型结构；采用MOCVD设备在V型结构内依次生长缓冲层、隔离层和多量子阱层；采用磁控溅射的方法，在多量子阱层上沉积SiO₂介质层，然后在顶面沉积金属层，完成器件的制备；选择合适的泵浦光源照射金属层和介质层交界面，激发表面等离子体波，产生激射光。本发明在Si衬底上的V型纳米沟槽内异质外延高质量的InGaAs/InP多量子阱结构，从而在纳米尺度的谐振腔内实现Si基纳米激光器的激射，实现与微电子器件的尺寸相匹配，实现Si基光电集成的目的。The invention relates to a preparation method of a silicon-based nano-laser based on surface plasmon: growing a _SiO2 base layer on a silicon substrate; adopting a combined method of ICP dry etching and HF wet etching on the _SiO2 layer A plurality of trenches were etched along the <110> direction of the Si substrate; washed with HF solution and deionized water, respectively, to remove the remaining SiO ₂ base layer at the bottom of the trench, exposing the silicon substrate; KOH solution was used to etch the trenches in the trenches. The bottom is extended to the silicon substrate to etch a V-shaped structure with an upward opening; MOCVD equipment is used to sequentially grow a buffer layer, an isolation layer and a multi-quantum well layer in the V-shaped structure; the magnetron sputtering method is used to grow the multi-quantum well layer on the multi-quantum well layer. The _SiO2 dielectric layer is deposited, and then the metal layer is deposited on the top surface to complete the preparation of the device; an appropriate pump light source is selected to illuminate the interface between the metal layer and the dielectric layer to excite surface plasmon waves and generate lasing light. In the present invention, a high-quality InGaAs/InP multi-quantum well structure is heteroepitaxially grown in a V-shaped nano-groove on a Si substrate, thereby realizing the lasing of a Si-based nano-laser in a nano-scale resonant cavity, and realizing integration with microelectronic devices. The size is matched to achieve the purpose of Si-based optoelectronic integration.

Description

Silicon-based nano laser based on surface plasmon and preparation method thereof

Technical Field

The invention belongs to the technical field of nano lasers, and particularly relates to a silicon-based nano laser based on Surface plasmons, which combines an Aspect Ratio trench confinement (ART) technology and Surface Plasmon Polariton (SPP) technology, and prepares the nano laser by growing an InGaAs/InP multi-quantum well material in the ART structure trench.

Background

Si is currently the most important semiconductor material in the modern microelectronics industry. For more than half a century, integrated circuits based on Si-based transistors have enjoyed tremendous success as guided by moore's law and provide a reliable material base for the development of the information society. However, as integrated circuit technology advances below the 10nm technology node, Si-based integrated circuit technology is limited by a series of fundamental physical and process technology problems in terms of speed, power consumption, integration level, reliability, etc., and expensive production line construction and manufacturing costs make the integrated circuit industry at a significant investment risk, the development pattern of conventional Si CMOS technology using "scaling down" to achieve smaller, faster, and cheaper logic and memory devices has been difficult to continue, and the development of moore's law has been challenged. In order to solve the physical limitation and power consumption bottlenecks encountered in the microelectronic development, people consider to use photons as information carriers to realize higher-speed information processing, transmission and larger-capacity information storage. With the development of the information age, the processing and transmission rate of information is required to be faster, the bandwidth is larger, the cost is lower, the power consumption is less, and the performance is more reliable. The integration of photoelectrons is a reliable way to achieve this goal by combining electronics and photonics. Therefore, the major role of electronics is shifted to photonics, so that the Si-based photonics of Si-based photonic integrated devices is realized, and the major international semiconductor manufacturers and research institutions also accelerate the pace of Si-based photonic integration.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a silicon-based nano laser based on surface plasmon, which is based on the research work of heteroepitaxy high-quality InGaAs/InP multiple quantum well structure in a V-shaped nano groove on a Si substrate, and is prepared by a simple process on the silicon-based nano laser, surface plasmon waves are excited at the interface of a metal layer and a dielectric layer, the diffraction limit is broken through, the lasing of the Si-based nano laser is realized in a nano-scale resonant cavity, the size matching with a microelectronic device is realized, and the purpose of Si-based photoelectric integration is realized.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a silicon-based nano laser based on surface plasmons provides a method for growing an InGaAs/InP multi-quantum well material nano laser in an Aspect Ratio limiting technology (ART) groove, and specifically comprises the following steps:

step 1: growing SiO on silicon substrate₂A base layer;

step 2: the method of combining ICP dry etching and HF wet etching is adopted to etch SiO₂Layered along the Si substrate<110>Etching a plurality of grooves in the direction;

and step 3: cleaning with 2.5% HF solution and deionized water respectively to remove residual SiO at the bottom of the trench₂A layer exposing the silicon substrate;

and 4, step 4: adopting 45% KOH solution, extending and corroding a V-shaped structure with an upward opening from the bottom of the groove to the silicon substrate;

and 5: sequentially growing a buffer layer, an isolation layer and a multi-quantum well layer in the V-shaped structure by using MOCVD equipment;

step 6: depositing SiO on the multi-quantum well layer by adopting a magnetron sputtering method₂A dielectric layer, thenDepositing a metal layer on the top surface to finish the preparation of the device;

and 7: and selecting a proper pump light source to irradiate the interface of the metal layer and the dielectric layer, and exciting surface plasma waves to generate exciting light.

Specifically, SiO grows on the silicon substrate in step 1₂The thickness of the base layer is preferably 600-700 nm.

Further preferably, the width of the V-shaped structure in step 4 is 200-.

Further preferably, the buffer layer in step 5 is made of GaAs; growing in two steps, wherein a GaAs low-temperature buffer layer grows at the temperature of 400 ℃, and a GaAs high-temperature epitaxial layer grows at the temperature of 600-; the growth rate of the GaAs low-temperature buffer layer and the growth rate of the GaAs high-temperature epitaxial layer are both 0.18-0.2nm/s, and the growth thickness is both 180-200 nm.

Further preferably, the material of the isolation layer in the step 5 is InP; growing in two steps, wherein an InP nucleating layer grows at the temperature of 450 ℃, and an InP top layer grows at the temperature of 600 ℃ and 650 ℃; the growth rate of the InP nucleation layer and the growth rate of the InP top layer are both 0.2-0.3nm/s, and the growth thickness is both 200-300 nm.

Further preferably, the material of the multiple quantum well layer in step 5 is InGaAs/InP, wherein the thickness of the InGaAs layer is 3nm, the thickness of the InP layer is 6nm, the growth period is 4, the growth temperature is 600-650 ℃, the growth rate is 0.03-0.04nm/s, and the growth thickness is 30-40 nm.

Specifically, SiO in step 6₂The deposition of the dielectric layer can adopt MOCVD equipment, and the deposition thickness is 4-20 nm.

Further preferably, the material of the metal layer in step 6 is Ag, a magnetron sputtering device is adopted, 20W is sputtered at normal temperature and low power, and the thickness of the Ag film is 150-300 nm.

Specifically, in step 7, the wavelength of the pump light source is required to be 1540-.

The invention also provides the silicon-based nano laser based on the surface plasmon prepared by the preparation method.

Based on the requirements of Si-based light sources, the invention researches Si-based nano-lasers based on surface plasmonsA light device. Based on ART scheme, the InGaAs/InP multi-quantum well material with excellent shape of epitaxy in V-shaped structure of Si substrate is used as an active region and passes through a metal Ag layer and SiO₂And (3) depositing the dielectric layer, exciting surface plasmons on the interface of the dielectric layer, and realizing lasing in the nano-sized resonant cavity, thereby realizing the Si-based surface plasmon nanometer laser. The realization of the laser can avoid the damage of the material caused by the preparation of the nano device by adopting a complex electron beam lithography process and dry etching internationally at present, and lays a good foundation for the realization of the nano device on the Si base; more importantly, the III-V group nanoscale photoelectric material is directly extended on the Si substrate, and the Si-based nano laser has greater application potential in future Si-based nano lasers corresponding to the traditional Si-based bonding scheme of nano lasers. Compared with the prior art, the invention has the following characteristics and beneficial effects:

1) the Si-based light source is a core device in the field of Si-based photonic integration. The invention adopts a direct epitaxial mode to obtain the nano-scale Si-based laser, thereby effectively overcoming the difficulty that the radiation composite luminous efficiency is low and the practical Si-based light source is difficult to realize because Si is used as an indirect band gap semiconductor;

2) through theoretical analysis and relevant simulation research, a structure of a surface plasmon-based Si-based nano laser is provided, and devices are directly prepared on a multi-quantum well material in a V-shaped nano groove, so that the damage of the current internationally adopted complex electron beam lithography process and dry etching to the material can be avoided, the process is simple, the production efficiency is improved, and the method has great practical value.

Drawings

FIG. 1 is a schematic flow chart of step 1 in the process of preparing a silicon-based nano-laser in example 1;

FIG. 2 is a schematic flow chart of step 2 in the process of preparing a silicon-based nano-laser in example 1; the right drawing in fig. 2 is a side view of the left drawing;

FIG. 3 is a schematic flow chart of

steps

3 and 4 in the process of preparing a silicon-based nano-laser in example 1;

FIG. 4 is a schematic flow chart of step 5 in the process of preparing a silicon-based nano-laser in example 1;

FIG. 5 is a schematic flow chart of step 6 in the process of manufacturing a silicon-based nano-laser in example 1; in the figure, 1 is a silicon substrate, 2 is SiO₂A base layer, 3 is a groove, 4 is a buffer layer, 5 is an isolation layer, 6 is a multi-quantum well layer, 7 is SiO₂A dielectric layer 8 is a metal Ag layer;

FIG. 6 is a two-dimensional electric field distribution diagram of a Si-based nano-laser designed in example 1;

FIG. 7 is a graph of the normalized electric field distribution of FIG. 6 along the horizontal dashed line;

FIG. 8 is the normalized electric field profile of FIG. 6 along the vertical dashed line.

Detailed Description

The technical solution of the present invention is further described in detail with reference to the following examples, but the scope of the present invention is not limited thereto.

Example 1

Referring to fig. 1 to 4, the invention provides a preparation method of a surface plasmon-based silicon-based nano laser, which is a method for growing an InGaAs/InP multiple quantum well material nano laser in an ART structure trench, and specifically comprises the following steps:

step 1: growing SiO on the silicon substrate 1 by conventional thermal oxidation method₂Base layer 2 of SiO₂The thickness of the base layer 2 is 600nm, see fig. 1. Using high aspect ratio limiting technique, using SiO with AR > 1₂The trenches serve to better limit misfit dislocation and Anti-phase Domain (APD) formation.

Step 2: by adopting an ICP dry etching method on SiO₂Along the silicon substrate on a base layer 2<110>A plurality of grooves are etched in the direction, the width of the groove 3 is 300nm, and the depth and SiO are equal₂The thickness of the layer 2 is approximately the same, see fig. 2. In order to improve the smoothness of the side wall, an HF solution (mass percent, the same applies below) with the concentration of 2.5% is selected and treated by a wet etching method, and the treatment time is 25S.

And step 3: cleaning with 2.5% HF solution (2 s) and a large amount of deionized water (10 min), respectively, to remove the trenchesSiO remaining at the bottom of the tank₂Layer 2, exposing the silicon substrate, see fig. 3. This step entails cleaning the bottom residual silicon dioxide layer to provide good growth conditions and growth conditions for the subsequent growth of material in the trenches.

And 4, step 4: anisotropically etching the silicon substrate 1 for about 14min by using 45% KOH solution (mass percent), and extending and etching the bottom of the trench 3 to form a V-shaped structure with an upward opening, as shown in FIG. 3; the width of the V-shaped structure is 300nm, and the depth is 200 nm. KOH solution to Si and SiO₂Has a large selection ratio, and almost does not react to SiO in the process of etching the bottom silicon substrate₂The side wall generates large damage, simultaneously ensures that chemical reaction products on the surface of the Si are thoroughly cleaned, can ensure a good Si interface, and ensures the epitaxial quality of the subsequent multi-quantum well material.

And 5: by using MOCVD equipment, a buffer layer 4, an isolation layer 5 and a multi-quantum well layer 6 are grown in the V-shaped structure 3 in sequence, as shown in FIG. 4. The buffer layer is made of GaAs; growing in two steps, wherein a GaAs low-temperature buffer layer grows at the temperature of 400 ℃, and a GaAs high-temperature epitaxial layer grows at the temperature of 600 ℃; the growth rates of the GaAs low-temperature buffer layer and the GaAs high-temperature epitaxial layer are both 0.2nm/s, and the growth thicknesses are both 200 nm. The isolation layer is made of InP; growing in two steps, wherein an InP nucleating layer grows at the temperature of 450 ℃, and an InP top layer grows at the temperature of 600 ℃; the growth rate of the InP nucleation layer and the growth rate of the InP top layer are both 0.3nm/s, and the growth thickness of the InP nucleation layer and the InP top layer are both 300 nm. The material of the multi-quantum well layer is InGaAs/InP, wherein the thickness of the InGaAs layer is 3nm, the thickness of the InP layer is 6nm, the growth period is 4, the growth temperature is 600 ℃, the growth rate is 0.03nm/s, and the growth thickness is 36 nm.

Step 6: the preparation method of the surface plasmon-based Si-based nano laser device comprises the steps of depositing SiO on a multi-quantum well layer (namely on the basis of Si-based InGaAs/InP multi-quantum well material) by adopting a magnetron sputtering method₂Dielectric layer 7 to SiO₂The base layer 2 is leveled and a layer 8 of metallic Ag is then deposited on the top surface to complete the device, see fig. 5. SiO 2₂The dielectric layer 7 can be deposited by using an MOCVD device, and the deposition thickness is 20 nm. The metal Ag layer 8 adopts magnetron sputtering equipment, 20W is sputtered at normal temperature and low power, and the thickness of the Ag filmIs 300 nm. When the external light irradiates, the SPP mode is in SiO₂The interface of the dielectric layer 7 and the metal Ag layer 8 is excited.

And 7: selecting proper pump light source to irradiate the metal Ag layer 8 and the SiO₂The interface of the dielectric layer 7 excites the surface plasma wave to generate the laser light. The wavelength of the pumping light source is required to be 1550nm, and the coupling output power is larger than uW magnitude.

And 8: a laser model is established by utilizing COMSOL Multiphysics software, and the mode distribution of SPP and a specific excitation mechanism are determined through simulation detailed analysis. From the two-dimensional electric field distribution, the metal Ag layer and SiO layer₂The SPP mode generated at the interface of the dielectric layers couples with the high index gain mode such that the electric field maximum is located at the gap between the metal layer and the gain medium and decays rapidly away from the interface (see fig. 6). From the normalized electric field distribution in the horizontal and vertical directions at the gap, it can be seen more intuitively that there is a very obvious field enhancement effect at the intersection of the two straight lines, and the model can realize energy constraint and high localization of the optical field distribution (see fig. 7-8).

And excitation of SPP mode and device performance analysis. After the device is prepared, a proper pump light source is selected to irradiate the interface of the metal and the dielectric layer, and surface plasma waves are excited to be continuously amplified in the nano resonant cavity, so that lasing is finally generated. Further, the specific lasing wavelength, the electrical characteristics, the sensitivity to temperature and the specific distribution of lasing spots can be determined by testing and analyzing the lasing performance (the testing means includes PL spectrum test, optical power test, temperature stability test, coupling efficiency test, light spot test, etc.). The present application has been learned through the above theoretical analysis that a silicon-based nano laser can be obtained, and therefore, a test result of related performance is not provided for now.

The invention relates to silicon-based photonic integration and has important application prospect in the aspect of optical interconnection. High performance miniaturized silicon-based light sources are a future development trend for silicon-based photonic integration. The surface plasmon-based nano laser is a novel technical means for realizing a miniaturized silicon-based light source, and surface plasmon is realizedThe body replaces photons, breaks through the diffraction limit, and realizes resonance in a nano-scale resonant cavity. The method utilizes the selective area epitaxy growth InGaAs/InP multiple quantum well material in the nano-scale V-shaped groove of the silicon substrate, deposits the metal layer Ag through magnetron sputtering, and grows the dielectric layer SiO through MOCVD₂And exciting surface plasmons at the interface to realize the lasing of the silicon-based nano laser based on the surface plasmons.

Claims

1. a preparation method of a silicon-based nano-laser based on surface plasmon, is characterized in that, comprises the following steps:

Step 1: grow a _SiO2 base layer on a silicon substrate;

Step 2: Several trenches are etched along the <110> direction of the Si substrate on the SiO ₂ layer by a combination of ICP dry etching and HF wet etching;

Step 3: Wash with HF solution and deionized water respectively to remove the remaining _SiO2 base layer at the bottom of the trench, exposing the silicon substrate;

Step 4: Using KOH solution, extend and etch a V-shaped structure with an upward opening at the bottom of the trench toward the silicon substrate;

Step 5: using MOCVD equipment to sequentially grow the buffer layer, the isolation layer and the multiple quantum well layer in the V-type structure;

Step 6: use the method of magnetron sputtering to deposit a _SiO2 dielectric layer on the multiple quantum well layer, and then deposit a metal layer on the top surface to complete the preparation of the device;

Step 7: Select a suitable pump light source to illuminate the interface between the metal layer and the dielectric layer to excite surface plasmon waves to generate lasing light.

2 . The method for preparing a silicon-based nanolaser based on surface plasmon according to claim 1 , wherein the thickness of the SiO ₂ base layer grown on the silicon substrate in step 1 is 600-700 nm. 3 .

3 . The method for preparing a silicon-based nanolaser based on surface plasmon according to claim 1 , wherein in step 4, the width of the V-shaped structure is 200-300 nm, and the depth is 180-200 nm. 4 .

4. the preparation method of the silicon-based nanolaser based on surface plasmon according to claim 1, is characterized in that, in step 5, the material of buffer layer is GaAs; Divide two-step growth, grow GaAs low temperature when temperature is 400 ℃ For the buffer layer, the GaAs high temperature epitaxial layer is grown at a temperature of 600-650 ℃; the growth rate of the GaAs low temperature buffer layer and the GaAs high temperature epitaxial layer are both 0.18-0.2nm/s, and the growth thickness is 180-200nm.

5. The preparation method of the silicon-based nanolaser based on surface plasmon according to claim 1, wherein in step 5, the material of the isolation layer is InP; For the nucleation layer, the InP top layer is grown at a temperature of 600-650 °C; the growth rates of the InP nucleation layer and the InP top layer are both 0.2-0.3 nm/s, and the growth thicknesses are both 200-300 nm.

6. the preparation method of the silicon-based nanolaser based on surface plasmon according to claim 1, is characterized in that, in step 5, the material of multiple quantum well layer is InGaAs/InP, wherein the thickness of InGaAs layer is 3nm, InP The thickness of the layer is 6 nm, the growth period is 4, the growth temperature is 600-650° C., the growth rate is 0.03-0.04 nm/s, and the growth thickness is 30-40 nm.

7. The method for preparing a silicon-based nanolaser based on surface plasmon according to any one of claims 1 to 6, wherein in step 6, the deposition of the _SiO2 dielectric layer adopts MOCVD equipment, and the deposition thickness is 4-20nm .

8. the preparation method of the silicon-based nanolaser based on surface plasmon according to claim 7, is characterized in that, in step 6, the material of metal layer is Ag, adopts magnetron sputtering equipment, and sputters 20W at room temperature and low power , the Ag film thickness is 150-300nm.

9 . The method for preparing a silicon-based nanolaser based on surface plasmon according to claim 8 , wherein in step 7, the wavelength of the pump light source is required to be 1540-1560 nm, and the coupled output power is greater than the order of uW. 10 .

10. The silicon-based nanolaser based on surface plasmon prepared by the preparation method according to any one of claims 1 to 9.