Wettability and Surface Energy of Hydrogen- and Oxygen-Terminated Diamond Films*

Abstract

The contact angle and surface energy values of diamond are systemically investigated in terms of surface treatments (hydrogen- and oxygen-terminations), structure feature (single crystal diamonds and polycrystalline diamond films), crystal orientation ((100), (111) and mixed (100)/(111) orientations), different fluids (probes of polar deionized water and nonpolar di-iodomethane). It is found that the hydrophobic/hydrophilic characteristic and surface energy values of diamond are mainly determined by the surface hydrogen/oxygen termination, and less related to the structural features and crystal orientation. Based on the contact angle values with polar water and nonpolar di-iodomethane, the surface energies of diamond are estimated to be about 43 mJ/m2 for hydrogen-termination and about 60 mJ/m2 for oxygen-termination. Furthermore, the varying surface roughness of diamond and fluids with different polarities examined determine the variation of contact angles as well as the surface energy values. These results would be helpful for a more detailed understanding of the surface properties of diamond films for further applications in a broad number of fields, such as optical and microwave windows, biosensors, and optoelectronic devices, etc.

Selective deposition of silver particles on {111} or {100} diamond facets

“…45, the surface energies of the (100) and (111) facets in the relaxed state were calculated to be 6.639 J m −2 and 2.772 J m −2 , respectively When the surface of diamond is functionalized, the surface energy of the facets decreases dramatically. 46 In the case of oxygen-termination, the surface energies of the {100} and {111} facets are quite close to each other (0.05–0.06 J m −2 ). This is higher than the surface energy in the case of hydrogen-termination (0.04 J m −2 ).…”

Structure and Wettability Engineering of Polycrystalline Diamond Films Treated by Thermally Oxidation, Second Growth and Surface Termination

“…In fact, there are many kinds of factors such as crystal orientation, surface termination, surface structure, grain size, and roughness, which affect the wettability and surface energy. [5] Therefore, the data recorded in this work provide additional information of diamond features and properties in various stages.…”

“…The majority of nanocrystalline diamond and/or nondiamond-phase carbonaceous nanoparticles appearing at grain boundaries could be oxidized and vaporized, and the large microsized grains were maintained. [5,11] This treated sample was named as sample B. The oxidized sample was sent back to the MPCVD chamber for the second growth process (sample C).…”

“…Because oxygen-terminated diamond has enhanced polarity, it has a strong adsorption effect on polar molecules. [5] The wettability feature with a modulated surface polarity could be applied widely in the fields of catalyst, optoelectronics, etc. [25] As presented in Table 2, the proportion of the polarity component on the O-terminated diamond surface is much higher than that of the H-terminated diamond surface.…”

Surface Oxygen Adsorption and Electric Property of Hydrogen-Terminated Single Crystal Diamonds by UV/ozone Treatment*

“…The saturated contact angles are larger than those for UV/ozone treated ultrananocrystalline diamonds (having a small contact angle of ∼10 ∘ at ∼8% oxygen content), [15] due to the significant differences in surface structure and morphology. [19,20] It is known that the diamond with H-termination (Otermination) is hydrophobic (hydrophilic) with a contact angle region of 90 ∘ -160 ∘ (0 ∘ -90 ∘ ), which can be further modulated by introducing some special rough surface designs. [19−22] For single crystal diamonds with smooth surface, hydrogenation or oxygenation plays a key role in determining its wettability, i.e., the hydrogenated (oxygenated) surface has a contact angle of about 90 ∘ (40 ∘ -50 ∘ ).…”