Abstract
Due to their atomic thicknesses and semiconducting properties, two-dimensional transition metal dichalcogenides (TMDCs) are gaining increasing research interest. Among them, Hf- and Zr-based TMDCs demonstrate the unique advantage that their oxides (HfO2 and ZrO2) are excellent dielectric materials. One possible method to precisely tune the material properties of two-dimensional atomically thin nanomaterials is to adsorb molecules on their surfaces as non-bonded dopants. In the present work, the molecular adsorption of NO2 and NH3 on the two-dimensional trigonal prismatic (1H) and octahedral (1T) phases of Hf and Zr dichalcogenides (S, Se, Te) is studied using dispersion-corrected periodic density functional theory (DFT) calculations. The adsorption configuration, energy, and charge-transfer properties during molecular adsorption are investigated. In addition, the effects of the molecular dopants (NH3 and NO2) on the electronic structure of the materials are studied. It was observed that the adsorbed NH3 donates electrons to the conduction band of the Hf (Zr) dichalcogenides, while NO2 receives electrons from the valance band. Furthermore, the NO2 dopant affects than NH3 significantly. The resulting band structure of the molecularly doped Zr and Hf dichalcogenides are modulated by the molecular adsorbates. This study explores, not only the properties of the two-dimensional 1H and 1T phases of Hf and Zr dichalcogenides (S, Se, Te), but also tunes their electronic properties by adsorbing non-bonded dopants.
Highlights
Nanomaterials often manifest fascinating and useful properties, which can be exploited for a variety of applications [1,2,3,4,5,6,7,8,9]
Two-dimensional transition metal dichalcogenides (TMDCs) are gaining research interest due to their atomic thickness and unique mechanical, electric, and optical properties, further, they are considered as promising high-performance electronic and optoelectronic materials [15,16]
Zr- and Hf-based TMDCs demonstrate a moderate bandgap comparable to Si. They demonstrate the unique advantage that their native oxides (ZrO2 and HfO2) are excellent dielectric materials, which show potential to replace Si in semiconductor technology [20]. These TMDCs exhibit ohmic contact like Si with their native oxides, which enable the isolation of components, and they demonstrate a reduced leakage current compared to Si transistors
Summary
Nanomaterials often manifest fascinating and useful properties, which can be exploited for a variety of applications [1,2,3,4,5,6,7,8,9]. Two-dimensional transition metal dichalcogenides (TMDCs) are gaining research interest due to their atomic thickness and unique mechanical, electric, and optical properties, further, they are considered as promising high-performance electronic and optoelectronic materials [15,16]. Depending on their chemical compositions and structural configurations, 2D TMDC materials can be categorized as metallic, semimetallic, semiconducting, insulating, or superconducting. They demonstrate the unique advantage that their native oxides (ZrO2 and HfO2) are excellent dielectric materials, which show potential to replace Si in semiconductor technology [20] These TMDCs exhibit ohmic contact like Si with their native oxides, which enable the isolation of components, and they demonstrate a reduced leakage current compared to Si transistors. 1.01 calc.: calculated values from literature, exp’t: experimental values from literature [33,34,35,36]
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