Method for reducing contact resistance between metal electrode and two-dimensional material by laser shock

Abstract

This invention discloses a method for reducing the contact resistance between a metal electrode and a two-dimensional material using laser shock. After establishing contact between the electrode and the two-dimensional material, laser shock treatment can bring the two-dimensional material and the electrode into close contact, reduce the contact distance between the two-dimensional material and the metal, lower the Schottky barrier, increase the contact area, and further reduce the contact resistance. The reduction in contact resistance can reduce the power consumption of two-dimensional material optoelectronic devices and improve the performance of the devices.

Description

Technical Field

[0001] This invention relates to the field of field-effect transistor fabrication technology, and specifically to a method for reducing the contact resistance between a metal electrode and a two-dimensional material using laser shock. Background Technology

[0002] In transistor devices, reducing the contact resistance between the metal and the channel material is crucial. In traditional semiconductor materials, good ohmic contacts can be achieved by introducing doping processes into the metal-semiconductor contact region. However, for emerging two-dimensional materials, alternative approaches may be necessary.

[0003] The Fermi level position of semiconductor materials changes with the type and concentration of doping, but there are still cases where doping cannot alter the Fermi level, known as Fermi level pinning. Fermi level pinning exists in the contact between two-dimensional materials and metals. One method to eliminate Fermi level pinning is to weaken the hybridization by inserting other materials between the two-dimensional material and the metal, which significantly reduces contact resistance and Schottky barrier height. Another method is to enhance the hybridization and metallize the two-dimensional material. In practice, two-dimensional materials often contain surface defects and impurities, which can significantly alter the metal-semiconductor contact. Surface defects can lead to gap states and cause Fermi level pinning. Resist residues can weaken the interaction between the metal and the two-dimensional material and may contribute to the formation of a tunnel barrier. Furthermore, the quality and fabrication process of the two-dimensional material affect the interface, further complicating the contact problem.

[0004] Generally, large-scale growth of single-layer two-dimensional materials generates numerous surface wrinkles. When a metal electrode is transferred onto these wrinkles, many surface gaps are created, affecting the interfacial resistance. Currently, there is no effective technology to address this increased resistance caused by surface wrinkles. Furthermore, for multilayer two-dimensional materials, the transferred metal electrode can only contact the outermost layer. Contact with other layers requires traversing the van der Waals gaps between the layers, increasing the energy barrier. Currently, there is also no technology to reduce this barrier. Summary of the Invention

[0005] The purpose of this invention is to provide a method for reducing the contact resistance between metal electrodes and two-dimensional materials by laser shock, thus providing a new approach to reducing the contact resistance of two-dimensional material optoelectronic devices and improving device performance.

[0006] To achieve the above objectives, the present invention provides a method for reducing the contact resistance between a metal electrode and a two-dimensional material using laser shock, characterized by comprising the following steps:

[0007] Step S1: Prepare the metal electrodes;

[0008] Step S2: Fabricate a dielectric layer-two-dimensional material structure, or a conductive layer-dielectric layer-two-dimensional material multilayer structure. The edges of the two-dimensional material can be selectively etched using lasers or other energy sources.

[0009] Step S3: Transfer the metal electrode over the two-dimensional material obtained in step S2 using a wet or dry method;

[0010] Step S4: On the multilayer structure obtained in step S3, a momentum transport layer, a sacrificial layer, and a plasma confinement layer are sequentially laid;

[0011] Step S5: Perform laser shock treatment, and remove the momentum transport layer, sacrificial layer and plasma confinement layer after treatment to obtain an interface-enhanced metal electrode in contact with the two-dimensional material.

[0012] As a preferred embodiment, in step S1, the metal electrode fabrication process includes magnetron sputtering, thermal evaporation, atomic layer deposition, electron beam evaporation, pulsed laser deposition, and direct metal writing; in step S1, the metal electrode material is a single metal, an alloy, or a multilayer metal.

[0013] Furthermore, in step S2, the two-dimensional material is a single layer or multiple layers, or a single crystal or polycrystalline material.

[0014] Furthermore, in step S4, the momentum transport layer and the sacrificial layer are composed of metal or its alloy, ceramic, or plastic; the plasma confinement layer is composed of gas, liquid, or solid.

[0015] Furthermore, in step S4, the momentum transport layer and the sacrificial layer are composed of metal or its alloy, ceramic, or plastic; the plasma confinement layer is composed of gas, liquid, or solid.

[0016] Furthermore, in step S5, the pulsed laser pulse width is less than 3 microseconds, the frequency is less than 1MHz, and the irradiation time is less than 60s.

[0017] The advantages and beneficial effects of this invention are as follows:

[0018] This invention provides a method for reducing the contact resistance between a metal electrode and a two-dimensional (2D) material using laser shock. By establishing contact between the 2D material and the electrode edge, laser shock increases the contact area between the electrode and the 2D material, further improving contact resistance. Using a contactless laser or other energy source to process the 2D material exposes its edges without contaminating the surface. After establishing contact between the electrode and the 2D material, laser shock treatment ensures tight contact, reducing the contact distance between the 2D material and the metal, lowering the Schottky barrier, increasing the contact area, and further reducing contact resistance. This reduced contact resistance lowers the power consumption of the 2D material optoelectronic device and improves its performance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of step S1 in an embodiment of the present invention for a single-layer two-dimensional material;

[0020] Figure 2 This is a schematic diagram of step S2 in an embodiment of the present invention for a single-layer two-dimensional material;

[0021] Figure 3 This is a schematic diagram of step S3 in an embodiment of the present invention for a single-layer two-dimensional material;

[0022] Figure 4 This is a schematic diagram of step S4 in an embodiment of the present invention for a single-layer two-dimensional material;

[0023] Figure 5 This is a schematic diagram of step S5 in an embodiment of the present invention for a single-layer two-dimensional material;

[0024] Figure 6 This is a schematic diagram of step S1 in an embodiment of the present invention for multilayer two-dimensional materials;

[0025] Figure 7 This is a schematic diagram of step S2 in an embodiment of the present invention for multilayer two-dimensional materials;

[0026] Figure 8 This is a schematic diagram of step S3 in an embodiment of the present invention for multilayer two-dimensional materials;

[0027] Figure 9 This is a schematic diagram of step S4 in an embodiment of the present invention for multilayer two-dimensional materials;

[0028] Figure 10 This is a schematic diagram of step S5 in an embodiment of the present invention for multilayer two-dimensional materials;

[0029] Figure 11 This is a graph showing the relationship between the source / drain current and the gate voltage under the same source / drain voltage according to the present invention.

[0030] Figure 12 This is a graph showing the relationship between the source / drain current and the source / drain voltage under the same gate voltage according to the present invention.

[0031] In the figure: 1. Substrate; 2. Metal electrode; 3. Two-dimensional material; 4. Momentum transport layer (can be composed of metal or its alloy, ceramic, or plastic); 5. Sacrificial layer (can be composed of metal or its alloy, ceramic, or plastic); 6. Plasma confinement layer (can be composed of gas, liquid, or solid); 7. Pulsed laser. Detailed Implementation

[0032] To better understand the present invention, the following description, in conjunction with embodiments and accompanying drawings, further illustrates the present invention, but the scope of the present invention is not limited to the embodiments described below.

[0033] Example 1

[0034] The electrode manufacturing and (dry and wet) transfer methods involved in this invention are existing technologies in semiconductor manufacturing and are not innovative points of this invention; they are merely applications.

[0035] A CVD-grown monolayer of molybdenum disulfide (MoD2) was transferred onto a clean silicon substrate on a 100 nm layer of SiO2, forming a MoD2-Si multilayer structure. A fabricated gold electrode was then transferred onto this structure. Due to the unavoidable wrinkling inherent in the MoD2 monolayer, a floating defect formed between the transferred gold electrode and the MoD2, resulting in high contact resistance. A momentum transport layer, a sacrificial layer, and a plasma confinement layer were sequentially deposited onto the gold electrode-MoD2-Si multilayer structure. The structure was then irradiated with a 100 mJ nanosecond pulse laser with a pulse width less than 10 nanoseconds for less than 1 second. The momentum transport layer, sacrificial layer, and plasma confinement layer were then removed, resulting in an enhanced gold electrode-MoD2 contact. Performance comparison figures are shown below. Figure 11 (The relationship between source / drain current and gate voltage under the same source / drain voltage) and Figure 12 The relationship between source / drain current and source / drain voltage under the same gate voltage is shown in the figure.

[0036] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for reducing the contact resistance between a metal electrode and a two-dimensional material using laser shock, characterized in that: Includes the following steps: Step S1: Prepare the metal electrodes; Step S2: Fabricate a dielectric layer-two-dimensional material structure, or a conductive layer-dielectric layer-two-dimensional material multilayer structure, by selectively etching the edges of the two-dimensional material using laser or other energy sources; the two-dimensional material may be a single layer or multiple layers, or a single crystal or polycrystalline material; Step S3: Transfer the metal electrode over the two-dimensional material obtained in step S2 using a wet or dry method; when the two-dimensional material is multilayered, the metal electrode simultaneously surrounds the sides of the multilayered two-dimensional material without contacting it; Step S4: On the multilayer structure obtained in step S3, a momentum transport layer, a sacrificial layer, and a plasma confinement layer are sequentially laid; Step S5: Perform laser shock treatment, and remove the momentum transport layer, sacrificial layer, and plasma confinement layer after treatment to obtain an interface-enhanced metal electrode in contact with the two-dimensional material; wherein, when the two-dimensional material is a single layer, laser shock changes the contact state between the two-dimensional material and the metal electrode from the two-dimensional material being located below the metal electrode and in contact with the lower surface of the metal to the two-dimensional material being located in the middle of the metal electrode and in contact with the side of the metal; when the two-dimensional material is multilayered, laser shock changes the contact state between the multilayered material and the metal electrode from only surface contact to an enclosed contact including edge contact; In step S1, the metal electrode fabrication process includes magnetron sputtering, thermal evaporation, atomic layer deposition, electron beam evaporation, pulsed laser deposition, and direct metal writing; in step S1, the metal electrode material is a single metal, an alloy, or a multilayer metal. In step S4, the momentum transport layer and the sacrificial layer are composed of metal or its alloy, ceramic, or plastic; the plasma confinement layer is composed of gas, liquid, or solid. In step S5, the pulsed laser pulse width is less than 3 microseconds, the frequency is less than 1 MHz, and the irradiation time is less than 60 s.

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