CN113206006A - Laser impact preparation method for two-dimensional material tensile strain engineering - Google Patents

Abstract

The invention discloses a laser shock manufacturing method for a two-dimensional material tensile strain engineering, which comprises the following steps: (1) depositing a metal film on a substrate; (2) forming metal nano particles on the deposited metal film in a heat treatment mode and the like; (3) transferring a single layer or a few layers of two-dimensional semiconductor materials on the metal film after the heat treatment; (4) the transferred two-dimensional material is processed using a pulsed laser shock method to create localized strain. The method for assisting the two-dimensional material to generate the strain by the laser shock can controllably generate the local strain on the premise of not damaging the two-dimensional material, can keep the local strain for a long time, changes the energy band structure of the two-dimensional material, greatly improves the electrical properties such as carrier mobility and the like of the two-dimensional material, and is suitable for electronic devices such as high-performance field effect transistors and the like.

Description

Laser impact preparation method for two-dimensional material tensile strain engineering

Technical Field

The invention relates to the technical field of two-dimensional semiconductor material strain engineering, in particular to a laser shock preparation method of two-dimensional material tensile strain engineering.

Background

In order to meet the requirement of high integration of semiconductor devices, the size of semiconductor devices is continuously reduced, but as the size of devices is continuously reduced, short channel effects are aggravated, and moore's law is gradually lost. In order to further improve the performance of the devices, researchers have begun to search for new electronic materials. Two-dimensional electronic materials stand out by virtue of the advantages of unique atomic-level thickness, excellent grid control capability and the like, become powerful competitors of next-generation semiconductor materials, and have great application potential in the fields of transistors, photodetectors and memories. The two-dimensional material is a relatively new atomic-level thin material, can effectively inhibit short channel effect, and is very suitable for next-generation ultrathin semiconductor devices. Theoretical and experimental results show that the band structure of two-dimensional materials is changed by introducing mechanical strain into the two-dimensional materials, so that it is possible to significantly adjust their electronic and photonic properties by using mechanical deformation. Strain engineering of two-dimensional materials has attracted considerable attention because the materials of a single atomic layer can inherently withstand greater mechanical strain than their corresponding bulk materials or conventional electronic materials. In-plane mode strain engineering of conventional semiconductors has been used to reduce interlayer scattering, improve carrier mobility in field effect transistors, and reduce the effective mass of holes in semiconductor lasers.

A widely used method for generating strain in a two-dimensional material at present is to transfer the two-dimensional material onto a substrate and introduce the strain into the two-dimensional material by controlling the deformation of the bulk substrate. These deformation modes include in-plane modes caused by epitaxy, thermal expansion mismatch, and stretching/compressing the substrate, as well as out-of-plane modes caused by wrinkling and warping of the two-dimensional material, transferring the two-dimensional material over a patterned substrate. The strain of the two-dimensional material caused by stretching/compressing the substrate disappears after the substrate recovers the original shape, which is not beneficial to practical application; the strain generated by the two-dimensional material has uncontrollable property by the modes of thermal expansion mismatch, wrinkling and warping of the two-dimensional material and the like; the transfer of two-dimensional materials on patterned substrates requires a reasonable structural design of the substrate, and high-precision patterning means such as electron beam lithography are often required for nano-scale patterning, so that the preparation cost is greatly increased. Therefore, it is of great interest to develop a method for creating a controlled strain in a two-dimensional material.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a laser impact preparation method for a two-dimensional material tensile strain engineering, which is characterized in that a two-dimensional material in contact with metal nanoparticles is locally deformed through laser impact to adjust an energy band structure of the two-dimensional material, so that the electrical property of the two-dimensional material is improved and the two-dimensional material is applied to two-dimensional material electronic devices.

In order to achieve the purpose, the invention provides a laser shock preparation method of a two-dimensional material tensile strain engineering, which comprises the following steps:

(1) depositing a metal film on a substrate;

(2) forming metal nano particles on the deposited metal film in a heat treatment mode and the like; (ii) a

(3) Transferring a single or few layers of a two-dimensional semiconductor material on the metal nanoparticles;

(4) and processing the transferred two-dimensional material by using a pulse laser impact method to generate local strain on the two-dimensional material.

Preferably, in the step (1), the substrate includes, but is not limited to, Si/SiO₂Si, quartz, sapphire.

Preferably, in the step (1), the deposited metal film includes, but is not limited to, Au, Ag, Al, Ti, Cu, and the film thickness is 1-20 nm.

Further, in the step (1), the metal thin film is deposited by one of magnetron sputtering, atomic layer deposition and chemical vapor deposition.

Furthermore, in the step (2), the heat treatment mode is tube furnace annealing, rapid annealing furnace annealing, laser annealing and the like. Further, in the step (4), the method of using pulsed laser shock specifically includes:

sequentially covering an absorption layer and a light transmission layer on the surface of the two-dimensional material, and vertically irradiating the light transmission layer by using pulse laser; pulse laserIncluding but not limited to nanosecond laser, picosecond laser and femtosecond laser, laser wavelength including but not limited to 1064nm, 532nm, 355nm and 266nm, frequency of 1Hz and above, laser power density of more than 10^-3GW/cm²The irradiation time is less than 1 min.

Further, in the step (4), in order to prevent the two-dimensional material from being damaged by the laser shock, it is preferable that deionized water is dropped between the absorption layer and the two-dimensional material.

The invention has the following advantages and beneficial effects:

the laser shock preparation method of the two-dimensional material tensile strain engineering of the invention utilizes physical or chemical deposition methods to deposit a metal film on the surface of a SiO2/Si substrate, obtains metal nano particles through annealing treatment, and utilizes the high-speed shock wave shock action generated by the pulse laser irradiation absorption layer to transfer the metal nano particles to the surface of the metal particles, so that the two-dimensional material locally deforms to generate 5% of strain. Compared with the method which is widely adopted at present and enables the two-dimensional material to generate stress by bending the substrate, the method can enable the local strain to be reserved for a long time in a laser shock mode, greatly improves the electrical properties such as carrier mobility of the two-dimensional material and the like, and is further used for electronic devices such as high-performance field effect transistors and the like.

Compared with the prior art, the method can obtain the metal nano particles with different gap sizes by controlling the thickness of the deposited film and carrying out simple annealing treatment, and can enable the two-dimensional material to generate plastic deformation on the surface of the metal nano particles through the laser shock effect; the strain rate of the two-dimensional material can be effectively regulated and controlled by adjusting the energy of the pulse laser, and meanwhile, the strain generated on the two-dimensional material by the method can be reserved.

Drawings

Fig. 1-5 are schematic diagrams of a laser shock preparation method for a two-dimensional material tensile strain engineering according to the present invention.

FIG. 1 is a schematic view of a substrate deposited with a metal thin film

FIG. 2 is a schematic view of a metal film after heat treatment

FIG. 3 is a schematic view of a metal nanoparticle/substrate transferred with a two-dimensional material

FIG. 4 is a schematic diagram of pulsed laser shock processing of a transferred two-dimensional material/metal nanoparticle/substrate

FIG. 5 is a schematic representation of a two-dimensional material after strain has been created

Wherein: SiO₂The manufacturing method comprises the following steps of A, a silicon substrate, 2, a metal thin film, 3, metal nano particles, 4, a two-dimensional material, 5, an absorption layer, 6, a light transmission layer and 7, wherein the two-dimensional material after deformation is formed.

FIG. 6 is an AFM image of Ag nanoparticles formed after heat treatment of an Ag thin film grown by magnetron sputtering;

FIG. 7 is a single layer of MoS transferred onto Ag nanoparticles₂An AFM map of (a);

FIG. 8 is a single layer MoS after pulsed laser shock treatment₂An AFM map of (a);

FIG. 9 shows MoS before and after pulsed laser shock₂The PL spectrum of (1).

Detailed Description

The following examples are provided to further illustrate the present invention for better understanding, but the present invention is not limited to the following examples.

The transfer, deposition, substrate and substrate involved in the present invention are all prior art, and are not innovative in the present invention, and are only applied here. The transfer includes, but is not limited to, dry transfer, wet transfer, or the like. Deposition methods include, but are not limited to, atomic layer deposition, chemical vapor deposition, magnetron sputtering, electron beam deposition, pulsed laser deposition, physical vapor deposition, and the like.

Example 1

The invention relates to a laser shock preparation method of a two-dimensional material tensile strain engineering, which comprises the following specific steps:

(1) mixing SiO₂TheSi substrate 1 is repeatedly cleaned in acetone, alcohol and deionized water and dried by nitrogen;

(2) using physical vapour deposition on SiO₂The surface of the/Si substrate 1 is deposited with anAg film 2 with the thickness of 2nm as shown in figure 1;

(3) putting the depositedAg film 2 into an annealing furnace to anneal in argon for 30min, and controlling the temperature at 300 ℃ to obtainAg nano particles 3;

(4) using a spin coater on SiO₂MoS grown on Si substrate₂Uniformly spin-coating PMMA solution, and drying in a vacuum environment at 100 ℃;

(5) curing the SiO with PMMA₂Soaking the/Si in 2mol/L potassium hydroxide solution for 1-2 hours, and naturally separating the PMMA film from the substrate;

(6) with SiO covered withAg nanoparticles 3₂Taking the PMMA film out of theSi substrate 1 from bottom to top, naturally airing, heating the substrate with the MoS2/PMMA by using a heating plate at the temperature of 80 ℃, and soaking and etching the PMMA by using acetone to obtain theMoS₂4 to theAg film 3, as shown in FIG. 3;

(10) to transferMoS₂4, drying the metal film; after the sample is dried, 1-2 drops of deionized water are dripped on the surface of the sample, and an aluminumfoil absorption layer 5 and alight transmission layer 6 with the thickness of 10 mu m of graphite are coated on the sample; using pulse laser emitted by Nd-YAG laser with pulse width of 10ns and wavelength of 1064nm to vertically irradiate light-transmitting layer, and controlling laser flux to be 17kJ/cm²Irradiation time of 1s, MoS after impact₂Deformation occurs to obtainstrain MoS₂7, as shown in fig. 4 and 5;

while the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims (9)

Translated fromChinese

1.一种二维材料拉应变工程的激光冲击制备方法，其特征在于：包括以下步骤：1. a laser shock preparation method of two-dimensional material tensile strain engineering, is characterized in that: comprise the following steps:(1)在基底上沉积金属薄膜；(1) depositing a metal film on the substrate;(2)将沉积的金属薄膜通过热处理方式形成金属纳米颗粒；(2) forming metal nanoparticles by heat treatment of the deposited metal film;(3)在金属纳米颗粒上转移单层或少层的二维半导体材料；(3) Transfer of single-layer or few-layer two-dimensional semiconductor materials on metal nanoparticles;(4)使用脉冲激光冲击的方法对转移的二维材料进行处理，使二维材料产生局部的应变。(4) The transferred two-dimensional material is processed by the method of pulsed laser shock, so that the two-dimensional material generates local strain.2.根据权利要求1所述的二维材料拉应变工程的激光冲击制造方法，其特征在于：所述步骤(1)中，基底包括Si/SiO₂、Si、石英和蓝宝石。2 . The laser shock manufacturing method for tensile strain engineering of two-dimensional materials according to claim 1 , wherein in the step (1), the substrate comprises Si/SiO₂ , Si, quartz and sapphire. 3 .3.根据权利要求1或2所述的二维材料拉应变工程的激光冲击制备方法，其特征在于：所述步骤(1)中，沉积的金属薄膜包括Au、Ag、Al、Ti和Cu，薄膜厚度为1-20nm。3. The laser shock preparation method of two-dimensional material tensile strain engineering according to claim 1 or 2, characterized in that: in the step (1), the deposited metal film comprises Au, Ag, Al, Ti and Cu, The film thickness is 1-20 nm.4.根据权利要求1或2所述的二维材料拉应变工程的激光冲击制备方法，其特征在于：所述步骤(1)中，沉积金属薄膜的方式为磁控溅射、原子层沉积或化学气相沉积中的任一种。4. The laser shock preparation method of two-dimensional material tensile strain engineering according to claim 1 or 2, characterized in that: in the step (1), the method of depositing the metal film is magnetron sputtering, atomic layer deposition or Any of chemical vapor deposition.5.根据权利要求3所述的二维材料拉应变工程的激光冲击制备方法，其特征在于：所述步骤(1)中，沉积金属薄膜的方式为磁控溅射、原子层沉积或化学气相沉积中的任一种。5. The laser shock preparation method of two-dimensional material tensile strain engineering according to claim 3, characterized in that: in the step (1), the method of depositing the metal film is magnetron sputtering, atomic layer deposition or chemical vapor phase any of the depositions.6.根据权利要求1或2或5所述的二维材料拉应变工程的激光冲击制备方法，其特征在于：所述步骤(2)中，热处理方式为管式炉退火、快速退火炉退火和激光退火。6. The laser shock preparation method of two-dimensional material tensile strain engineering according to claim 1, 2 or 5, characterized in that: in the step (2), the heat treatment method is tube furnace annealing, rapid annealing furnace annealing and Laser annealing.7.根据权利要求1或2或5所述的二维材料拉应变工程的激光冲击制备方法，其特征在于：所述步骤(4)中，使用脉冲激光冲击的方法具体为：7. The laser shock preparation method of two-dimensional material tensile strain engineering according to claim 1, 2 or 5, characterized in that: in the step (4), the method of using pulsed laser shock is specifically:在所述二维材料表面依次覆盖吸收层和透光层，利用脉冲激光垂直照射透光层；脉冲激光冲击所用激光器包括纳秒激光器、皮秒激光器和飞秒激光器；所述激光波长包括1064nm、532nm、355nm和266nm，频率为1Hz及以上，激光功率密度大于10^-3GW/cm²，照射时间小于1min。The surface of the two-dimensional material is sequentially covered with an absorption layer and a light-transmitting layer, and the light-transmitting layer is vertically irradiated by a pulsed laser; the lasers used in the pulsed laser shock include nanosecond lasers, picosecond lasers, and femtosecond lasers; the laser wavelengths include 1064 nm, 532nm, 355nm and 266nm, the frequency is 1Hz and above, the laser power density is greater than 10^-3 GW/cm² , and the irradiation time is less than 1min.8.根据权利要求6所述的二维材料拉应变工程的激光冲击制备方法，其特征在于：所述步骤(4)中，使用脉冲激光冲击的方法具体为：8. The laser shock preparation method of two-dimensional material tensile strain engineering according to claim 6, characterized in that: in the step (4), the method of using pulsed laser shock is specifically:在所述二维材料表面依次覆盖吸收层和透光层，利用脉冲激光垂直照射透光层；脉冲激光冲击所用激光器包括纳秒激光器、皮秒激光器和飞秒激光器；所述激光波长包括1064nm、532nm、355nm和266nm，频率为1Hz及以上，激光功率密度大于10^-3GW/cm²，照射时间小于1min。The surface of the two-dimensional material is sequentially covered with an absorption layer and a light-transmitting layer, and the light-transmitting layer is vertically irradiated by a pulsed laser; the lasers used in the pulsed laser shock include nanosecond lasers, picosecond lasers, and femtosecond lasers; the laser wavelengths include 1064 nm, 532nm, 355nm and 266nm, the frequency is 1Hz and above, the laser power density is greater than 10^-3 GW/cm² , and the irradiation time is less than 1min.9.根据权利要求1或2或5或8所述的二维材料拉应变工程的激光冲击制备方法，其特征在于：所述步骤(4)中，在吸收层和二维材料间滴加去离子水，以防止激光冲击对二维材料的损伤。9 . The laser shock preparation method of two-dimensional material tensile strain engineering according to claim 1 or 2 or 5 or 8, characterized in that: in the step (4), dropwise addition is performed between the absorption layer and the two-dimensional material. Ionized water to prevent laser shock damage to two-dimensional materials.

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