Wafer‐Scale Fabrication of 2D β‐In₂Se₃ Photodetectors

Abstract

Nevertheless, the research of 2D materials is still in its early stages. The field started with graphene several years ago, [3] but more materials have been added continuously to the list. Among these, transition metal dichalcogenides (TMDC), [4] which have impressive optical properties in the visible range, are currently one of the most studied 2D materials. Devices made of these materials have shown remarkable performance as photodetectors, [5,6] nonvolatile random access memory, [7] or photovoltaics, [8] even when using simple manual exfoliation methods. More recently, 2D indium selenides (In x Se y) have gained attention, [9] due to their bandgap in the visible spectral region, comparable to TMDCs, but also due to several novel properties: InSe exhibits one of the largest mobilities of 2D semiconductor materials, [10] and β-In 2 Se 3 shows good mobility, [11] excellent photoresponsivity, [12] and exotic ferroelectricity [13] (the ordered ferroelectric phase is also called β′-In 2 Se 3 by some authors). [11,13] Transistors with high mobility and on/off ratio have already been realized. [14] Therefore, 2D In 2 Se 3 materials have the potential to address several limitations of the current silicon (Si) and III-V technologies, such as improved mobility and overall performance of transistors for electronics, as well as integrated photodetectors and light emitters in the same material system (same die), all possible on virtually any substrate, including transparent and flexible substrates. [15,16] Yet, the majority of reported devices from 2D materials rely on fabrication methods based on exfoliation and transfer of layers onto other substrates or other 2D materials. While this device fabrication process allows unprecedented flexibility in the combination of materials and therefore has nearly unlimited device design possibilities, [1] it leads typically to individual or few devices and is a slow and tedious process. On the other hand, due to their layered nature, instead of strong covalent bonds (as in Si and compound semiconductors) van der Waals forces exist between the layers. Hence, 2D materials can be grown epitaxially on substrates with completely different lattice constants without creating the strain and the defects commonly found in mismatched heteroepitaxy. This method is called van der Waals (vdW) epitaxy. [17] Nevertheless, the substrate does influence the growth, [18] as it modifies the nucleation of the first layer. Some substrates provide growth with superior quality (amount of defects, 2D materials are considered the future of electronics and photonics, stimulated by their remarkable performance. Among the 2D materials family, β-In 2 Se 3 shows good mobility, excellent photoresponsivity, and exotic ferroelectricity, making it suitable for a wide variety of applications. To date, most reported devices from 2D materials in general, and β-In 2 Se 3 in specific, rely on cumbersome fabrication methods using mechanical exfoliation and transfer of layers onto other substrates. However, for a successful ado...

Retinomorphic optoelectronic devices for intelligent machine vision

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Epitaxial Growth of 2D Ternary Copper–Indium–Selenide Nanoflakes for High‐Performance Near‐Infrared Photodetectors

“…[26,28] The properties of the as-grown CIS nanoflakes were also better or comparable with those of other as-grown 2D materials. [35,58,62,63] Particularly in the near-infrared region, the as-grown CIS nanoflakes exhibited the outstanding optoelectrical characteristics that they were much better than those of the other as-grown 2D materials. [59][60][61] Furthermore, compared to the mechanical exfoliated multi-layer InSe, [8] the as-grown CIS nanoflakes were much sensitive to the weak near-infrared signal with higher photoresponsivity and specific detectivity.…”

Two-dimensional single crystal monoclinic gallium telluride on silicon substrate via transformation of epitaxial hexagonal phase

“…On the other hand, recent growth advances show that high-quality and strainfree PTMCs are not yet available and pristine material information are still inaccessible due to the formation of Te oxide on the surface 22 . In particular, limited reports are available on MBE of InSe 23 and GaSe 24,25 , whereas GaTe materials are at an early stage of development [26][27][28] .…”