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Ultra-wide bandgap; piezoelectricity; and spin–orbit coupling in cluster-assembled monolayers
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Y
苏
J
DOI：10.1088/1361-6463/ae5fa4.png)
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Abstract
En 中文
Two-dimensional (2D) ultra-wide bandgap (UWBG) semiconductors are essential for extreme-condition electronics and deep-ultraviolet (UV) optoelectronics, yet their diversity is limited. Here, have established tetrahedral [MCl4]2− clusters (M = Be, Mg, Ca, Sr, Fe, Co, Ni, Zn and Cd) as effective superatomic building blocks for designing a novel family of stable 2D MCl2 monolayers via a bottom-up cluster-assembly strategy. These monolayers exhibit UWBG semiconducting behavior with bandgaps ranging from 3.37 to 6.92 eV (HSE06), placing them alongside h-BN and Ga2O3 as wide-gap materials. They show strong deep-UV optical absorption with coefficients exceeding 105 cm−1, reaching 106 cm−1 for BeCl2 at ∼140 nm. Owing to their intrinsic non-centrosymmetric C4v structure, these monolayers simultaneously exhibit pronounced out-of-plane piezoelectricity with d31 coefficients up to 31.26 pm V−1 (CoCl2)—comparable to or exceeding many known 2D piezoelectrics—and a mix of Rashba–Dresselhaus spin–orbit coupling with constants αR–D ranging from 0.10 to 0.36 eV·Å at the Γ point, significantly larger than that of α-In2Se3 (0.097 eV·Å). All monolayers are dynamically and thermally stable, with formation energies between −1.03 and −1.89 eV atom−1. Our work establishes that this cluster-assembly approach successfully bypasses many core challenges of top–down fabrication (such as uncontrollable defect proliferation and the resulting performance degradation), enabling the atomically precise fabrication of low-symmetry 2D materials with tailored multifunctional properties for deep-UV optoelectronic and extreme-environment electronic applications.
Keywords:
Ultra-wide bandgap
piezoelectricity
spin–orbit coupling
cluster-assembled monolayers
deep-ultraviolet optoelectronics
Journal
J
IF:
3.2
Papers:
726
Citations:
0
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