MoS2 on an amorphous HfO2 surface: An <i>ab initio</i> investigation

Scopel, Wanderlã L.; Miwa, R. H.; Schmidt, T. M.; Venezuela, P.

doi:10.1063/1.4921058

Cited by 17 publications

(18 citation statements)

References 20 publications

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“…For reference, the KPFM measurement helps confirm that the work function of graphene was approximately 4.581 eV (Figure c). Another possible explanation is the presence of charge puddles due to charged impurities and adsorbed polar molecules on the surface of SiO 2 , which is known to cause p-doping in 2D materials. − We speculate that this charge-puddle effect probably enhanced the p-type properties of WSe 2 on SiO 2 to a greater extent compared to that of WSe 2 on graphene.…”

Section: Resultsmentioning

confidence: 95%

Light-Triggered Ternary Device and Inverter Based on Heterojunction of van der Waals Materials

Shim

Kim

et al. 2017

ACS Nano

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Multivalued logic (MVL) devices/circuits have received considerable attention because the binary logic used in current Si complementary metal-oxide-semiconductor (CMOS) technology cannot handle the predicted information throughputs and energy demands of the future. To realize MVL, the conventional transistor platform needs to be redesigned to have two or more distinctive threshold voltages (Vs). Here, we report a finding: the photoinduced drain current in graphene/WSe heterojunction transistors unusually decreases with increasing gate voltage under illumination, which we refer to as the light-induced negative differential transconductance (L-NDT) phenomenon. We also prove that such L-NDT phenomenon in specific bias ranges originates from a variable potential barrier at a graphene/WSe junction due to a gate-controllable graphene electrode. This finding allows us to conceive graphene/WSe-based MVL logic circuits by using the I-V characteristics with two distinctive Vs. Based on this finding, we further demonstrate a light-triggered ternary inverter circuit with three stable logical states (ΔV of each state <0.05 V). Our study offers the pathway to substantialize MVL systems.

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Section: Resultsmentioning

confidence: 95%

Light-Triggered Ternary Device and Inverter Based on Heterojunction of van der Waals Materials

Shim

Kim

et al. 2017

ACS Nano

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“…To simulate experimentally relevant situations, the amorphous SiO2 (a-SiO2) bulk structure was further generated through the molecular dynamics (MD) simulations based on the VASP code following the same procedure as showed in detailed in literatures [55,56]. The WS2/SiO2 heterostructure was further simulated by constructing a repeated-slab model, including a-SiO2, (3×3)-WS2, and a 20 Å vacuum region.…”

Section: Resultsmentioning

confidence: 99%

Band alignment of 2D WS2/HfO2 interfaces from x-ray photoelectron spectroscopy and first-principles calculations

Zhu

Zhou

Tang

et al. 2018

Applied Physics Letters

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Two-dimensional (2D) WS2 films were deposited on SiO2 wafers, and the related interfacial properties were investigated by high-resolution x-ray photoelectron spectroscopy (XPS) and first-principles calculations. Using the direct (indirect) method, the valence band offset (VBO) at monolayer WS2/SiO2 interface was found to be 3.97 eV (3.86 eV), and the conduction band offset (CBO) was 2.70 eV (2.81 eV).Furthermore, the VBO (CBO) at bulk WS2/SiO2 interface is found to be about 0.48 eV (0.33 eV) larger due to the interlayer orbital coupling and splitting of valence and conduction band edges. Therefore, the WS2/SiO2 heterostructure has a Type I energy-band alignment. The band offsets obtained experimentally and theoretically are consistent except the narrower theoretical bandgap of SiO2. The theoretical calculations further reveal a binding energy of 75 meV per S atom and the totally separated partial density of states, indicating a weak interaction and negligible Fermi level pinning effect between WS2 monolayer and SiO2 surface. Our combined experimental and theoretical results provide proof of the sufficient VBOs and CBOs and weak interaction in 2D WS2/SiO2 heterostructures.

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“…The thermal stability of HfO 2 , melting point (2700 C), will be ideal for a high temperature graphene growth environment. A recent theoretical study showed that there is no chemical bonding at the graphene-HfO 2 interface and its energetic stability is ruled by the van der Waals interaction [9]. In addition, HfO 2 /graphene structures exhibited ultra high mobility compared to other oxide/graphene structures [10,11] and welldeveloped half-integer quantum Hall states and magnetoresistance oscillations [12], similar to that of pristine exfoliated graphene [8].…”

Section: Introductionmentioning

confidence: 99%

Direct graphene growth on transitional metal with solid carbon source and its converting into graphene/transitional metal oxide heterostructure

Park

Back

Fairchild

et al. 2017

Carbon

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International audienceThe oxide/semiconductor structure is key to controlling current in electronic devices and HfO$_2$ is a common gate material in conventional electronic devices due to its favorable dielectric properties. Graphene devices also require insulating gates. We demonstrate a unique direct growth approach to obtain the bottom gate structure (graphene/HfO$_2$/n-SiC). The present approach involves transfer of graphene grown by chemical vapor deposition (CVD) on Cu to oxidized Si wafers, a complex process prone to low yield and reduced performance. Furthermore, HfO$_2$ is preferred to SiO$_2$ because of its superior properties. The proposed concept consists of the direct deposition of graphene by solid carbon molecular beam epitaxy on Hf metal coated n-type SiC, followed by oxygen intercalation to form HfO$_2$. The oxygen intercalation will then convert the underlying Hf into HfO$_2$ due to the strong affinity of Hf with oxygen. We identify the graphene/HfO 2 formation by Raman, X-ray photoelectron spectroscopy (XPS), Low energy electron diffraction (LEED), Low energy electron microscopy (LEEM) and electrical properties including Hall mobility and leakage current measurement

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MoS2 on an amorphous HfO2 surface: An ab initio investigation

Cited by 17 publications

References 20 publications

Light-Triggered Ternary Device and Inverter Based on Heterojunction of van der Waals Materials

Light-Triggered Ternary Device and Inverter Based on Heterojunction of van der Waals Materials

Band alignment of 2D WS2/HfO2 interfaces from x-ray photoelectron spectroscopy and first-principles calculations

Direct graphene growth on transitional metal with solid carbon source and its converting into graphene/transitional metal oxide heterostructure

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