- Electronic Applications of 2D Materials
- Sensors and Energy Devices Applications of 2D Materials
- Photonic and Optoelectronic Applications of 2D Materials
- Bio and Ecological Applications of 2D Materials
FET Based on 2D Materials
Alfa Chemistry has seen significant advances in the field of two-dimensional (2D) materials and electronics, which we believe is one of the most promising directions in nanoelectronics. Alfa Chemistry can create 2D material solutions that are unique to our customers. Please get in touch with us right away so that we can assist you with your FET application study.
Graphene Field-Effect Transistors
At ambient temperature, graphene's carrier mobility can approach 250000 cm2V-1s-1, making it excellent for FET operation. However, virgin graphene is gapless, which means that the energy band gap needs to be opened in order to be used for logical operations in graphene-based FETs.
Alfa Chemistry achieves graphene bandgap engineering using a plasma method. Nitrogen-containing radicals in graphene exfoliated on a silicon substrate can easily create covalent bonds within the carbon lattice using NH3 plasma. Controlling the plasma exposure period allows us to regulate the amount of charge carriers. Doped graphene has a variety of properties, ranging from p-type to bipolar and n-type. At temperatures up to 800 °C, our produced doped graphene is stable in both air and vacuum.
Fig 1. (a) A graphene nanoribbon of 33 nm made in rapid-heating plasma CVD. (b) IDS–VGS at 13 K and (c) Arrhenius plot of the 33 nm graphene nanoribbon. (Kato T, et al. 2012)
Another promising configuration for FETs is graphene heterostructures on h-BN. In terms of lattice orientation, sample homogeneity, and interfacial contamination, random stacking between graphene and h-BN may cause structural flaws. Alfa Chemistry chooses h-BN for epitaxial development of single-domain graphene on the material using a plasma-assisted deposition process. With this approach, continuous single or bilayer graphene can be grown with its orientation fixed on the h-BN substrate below. The quality of graphene single crystals formed in a plasma-assisted environment is demonstrated by electron transport studies.
MoS2 Field-Effect Transistors
Transition metal disulfides (TMDs) are inherently semiconductors, hence fabricating FET devices does not need band gap engineering. The capacity to manipulate the energy band structure of semiconductor materials via doping or defect engineering, on the other hand, is critical. For FET applications, MoS2 is one of the most investigated TMDs.
Alfa Chemistry manipulates the number and electrical properties of MoS2 layers, such as energy band structure, doping, and work function, using plasma technology. Because of the S vacancies in the structure, pristine MoS2 often possesses inherent n-doping behavior. We may induce p-type doping of MoS2 with fluorine-containing plasma chemicals, which is motivated by a strong desire to create complementary electronic circuits. After plasma treatment, p-n junctions in MoS2 show stable rectification behavior.
Fig 2. The 3D schematic view of dual-gated MoS2 monolayer transistors. (Radisavljevic B, et al. 2011)
Controlled O2 plasma exposure can also be used to make MoS2-based FETs with different layer thicknesses. Electron transport in MoS2 is highly n-doped when it is treated in O2 plasma at low power.
BP Field-Effect Transistors
Black phosphorus (BP) is a 2D substance having a 0.33 eV bulk bandgap and a 1.8 eV monolayer bandgap. Regardless of layer thickness, its energy band gap maintains the direct band gap property.
Alfa Chemistry achieves fully ordered atomic arrangements with no visible BP flaws using Ar plasma etching. Following the plasma etch technique, back-gate FETs were produced on SiO2/Si substrates with polymethylmethacrylate (PMMA) passivation. The p-type behavior of the exfoliated BP-based FET device is evident.
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- Kato T, et al. (2012). "Site- and Alignment-Controlled Growth of Graphene Nanoribbons from Nickel Nanobars." Nature Nanotechnology. 7: 651-656.
- Radisavljevic B, et al. (2011). "Single-Layer MoS2 Transistors." Nature Nanotechnology. 6: 147-150.
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