Comparative Study of Surface Energies of Native Oxides of Si(100) and Si(111) via Three Liquid Contact Angle Analysis

Narayan, S. P. Atul; Day, Jack M.; Thinakaran, Harshini L.; Herbots, Nicole; Bertram, M.; Cornejo, Christian E.; Diaz, Timoteo C.; Kavanagh, K. L.; Culbertson, Robert; Ark, Franscesca J.; Ram, Sukesh; Mangus, M.W.

doi:10.1557/adv.2018.473

Cited by 19 publications

(8 citation statements)

References 18 publications

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“…Defects are expected to increase γ T . On the other hand, both as-received p + Si (100) wafers are initially hydrophilic with a γ T of 59.7 ± 1.7 mJ/m 2 , consistent with a large number of previously characterized p + Si (100) [35].…”

Section: Gaas and Si Native Oxidessupporting

confidence: 85%

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GaAs to Si Direct Wafer Bonding at T ≤ 220°C in Ambient Air via Nano-BondingTM and Surface Energy Engineering (SEE)

Gurijala

Khanna

et al. 2021

Preprint

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When different semiconductors are integrated into hetero-junctions, native oxides generate interfacial defects and cause electronic recombination. Two state-of-the-art integration methods, hetero-epitaxy and Direct Wafer Bonding (DWB), require temperatures > 400°C to reduce native oxides. However, T > 400°C leads to defects due to lattice and thermal expansion mismatches. In this work, DWB temperatures are lowered via Nano-Bonding™ (NB) at T ≤ 220°C and P ≤ 60 kPa (9 psi). NB uses Surface Energy Engineering (SEE) at 300K to modify surface energies (γT) to far-from-equilibrium states, so cross-bonding occurs with little thermal activation and compression. SEE modifies γT and hydro-affinity (HA) via chemical etching, planarization, and termination that are optimized to yield 2-D Precursor Phases (2D-PP) metastable in ambient air and highly planar at the nano- and micro- scales. Complementary 2D-PPs nano-contact via carrier exchange from donor 2D-PP surfaces to acceptor ones. Here, NB models and SEE are applied to the DWB of GaAs to Si for photo-voltaics. SEE modifies (1) the initial γT0 and HA0 measured via Three Liquid Contact Angle Analysis, (2) the oxygen coverage measured via High Resolution Ion Beam Analysis, and (3) the oxidation states measured via X-Ray Photoelectron Spectroscopy. SEE etches hydrophobic GaAs oxides with γT = 33.4 ± 1 mJ/m2, and terminates GaAs (100) with H+, rendering GaAs hydrophilic with γT = 60 ± 2 mJ/m2. Similarly, hydrophilic Si native oxides are etched into hydrophobic SiO4H2. H+- GaAs nano-bonds reproducibly to Si, as measured via Surface Acoustic Wave Microscopy, validating the NB model and SEE design.

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Section: Gaas and Si Native Oxidessupporting

confidence: 85%

“…1.g. Such low relative variation indicates that dopants do not affect GaAs native oxide γ T0 unlike on Si [35]. 4 Experimental Procedure NB uses SEE to remove native oxides and planarize wafer surfaces by reducing macro-scale wafer warp and both nano-and micro-scale roughness.…”

Section: Nano-bonding ™ and Surface Energy Engineering (See) At T ≤ 220°cmentioning

confidence: 99%

GaAs to Si Direct Wafer Bonding at T ≤ 220°C in Ambient Air via Nano-BondingTM and Surface Energy Engineering (SEE)

Gurijala

Khanna

et al. 2021

Preprint

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“…Two distinct growth modes were identified for D(C 7 CO)-BTBT . Similar to that observed in C 8 -BTBT , the initial ~600 nm of the D(C 7 CO)-BTBT film showed dense packing of island-based morphology (VW growth mode), which is obviously a direct result of our modified PVD film growth dynamics 24 , 29 and the tendency of the crystal growth with lowest-energy surfaces ((200) for D(C 7 CO)-BTBT and (001) for C 8 - BTBT -based on BFDH) 40 covering the high-energy substrate surface ( γ = 52.5 mJ/m 2 for native oxide) 41 . Once this dense film is formed, growth mode in D(C 7 CO)-BTBT shows the transition into a highly porous 3D morphology forming loosely connected and vertically oriented nanoplates in the top-lying ~4.5–5.0 μm.…”

Section: Resultsmentioning

confidence: 94%

Enabling three-dimensional porous architectures via carbonyl functionalization and molecular-specific organic-SERS platforms

et al. 2021

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Molecular engineering via functionalization has been a great tool to tune noncovalent intermolecular interactions. Herein, we demonstrate three-dimensional highly crystalline nanostructured D(C7CO)-BTBT films via carbonyl-functionalization of a fused thienoacene π-system, and strong Raman signal enhancements in Surface-Enhanced Raman Spectroscopy (SERS) are realized. The small molecule could be prepared on the gram scale with a facile synthesis-purification. In the engineered films, polar functionalization induces favorable out-of-plane crystal growth via zigzag motif of dipolar C = O···C = O interactions and hydrogen bonds, and strengthens π-interactions. A unique two-stage film growth behavior is identified with an edge-on-to-face-on molecular orientation transition driven by hydrophobicity. The analysis of the electronic structures and the ratio of the anti-Stokes/Stokes SERS signals suggests that the π-extended/stabilized LUMOs with varied crystalline face-on orientations provide the key properties in the chemical enhancement mechanism. A molecule-specific Raman signal enhancement is also demonstrated on a high-LUMO organic platform. Our results demonstrate a promising guidance towards realizing low-cost SERS-active semiconducting materials, increasing structural versatility of organic-SERS platforms, and advancing molecule-specific sensing via molecular engineering.

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“… = 1.5 J/m 2 can be taken as an average value. The surface energy of SiO 2 can be determined through the contact angles of droplets (particles), which are formed due to the dewetting of various liquids on SiO 2 70 , 71 , including melted Ge 34 . This gives ~ 0.05 J/m 2 .…”

Section: Resultsmentioning

confidence: 99%

Dewetting behavior of Ge layers on SiO2 under annealing

Shklyaev

Латышев

2020

Sci Rep

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the solid-state dewetting phenomenon in Ge layers on Sio 2 is investigated as a function of layer thickness d Ge (from 10 to 86 nm) and annealing temperature. The dewetting is initiated at about 580-700 °C, depending on d Ge , through the appearance of surface undulation leading to the particle formation and the rupture of Ge layers by narrow channels or rounded holes in the layers with the thicknesses of 10-60 and 86 nm, respectively. The channel widths are significantly narrower than the distance between the particles that causes the formation of thinned Ge layer areas between particles at the middle dewetting stage. the thinned areas are then agglomerated into particles of smaller sizes, leading to the bimodal distributions of the Ge particles which are different in shape and size. The existence of a maximum in the particle pair correlation functions, along with the quadratic dependence of the corresponding particle spacing on d Ge , may indicate the spinodal mechanism of the dewetting in the case of relatively thin Ge layers. Despite the fact that the particle shape, during the solid-state dewetting, is not thermodynamically equilibrium, the use of the Young's equation and contact angles allows us to estimate the particle/substrate interface energy.

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Comparative Study of Surface Energies of Native Oxides of Si(100) and Si(111) via Three Liquid Contact Angle Analysis

Cited by 19 publications

References 18 publications

GaAs to Si Direct Wafer Bonding at T ≤ 220°C in Ambient Air via Nano-BondingTM and Surface Energy Engineering (SEE)

GaAs to Si Direct Wafer Bonding at T ≤ 220°C in Ambient Air via Nano-BondingTM and Surface Energy Engineering (SEE)

Enabling three-dimensional porous architectures via carbonyl functionalization and molecular-specific organic-SERS platforms

Dewetting behavior of Ge layers on SiO2 under annealing

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