Influence of relative humidity on the wettability of silicon wafer surfaces

Abstract

Investigation of wetting properties of the original silicon wafers and modified by oxidation was carried out by contact angles measurements of water at varying relative humidity (RH) of the atmosphere present in the measuring chamber. At three selected humidities (10, 30 and 50%) contact angles of diiodomethane and formamide were also determined for the original silicon wafer only. The topography of the tested surfaces was determined with the help of atomic force microscopy (AFM). Using the measured contact angles the total apparent surface free energy and its components of studied silicon wafers were determined using two models: the contact angle hysteresis (CAH) and Lifshitz-van der Waals acid-base (LWAB) approaches. In the former approach the advancing and receding contact angles are employed, and in the latter only the advancing angles. It was found that in the case of original silicon wafer the contact angels and surface free energy depend on the humidity only in the RH range from 10 to 40% with a minimum at 30% RH, and then they fluctuate around a mean value. For the oxidized silicon wafer the changes in the contact angles and the surface free energy depend on the relative humidity and change periodically with increasing RH. These changes can result from water adsorption on the hydrophilic silicon surface.

Effect of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and phospholipase A2 (PLA2) on surface properties of silica materials

“…The Lifshitz-van der Waals LW S component of the powdered quartz determined by the I-D method is 42.8 mJ/m 2 and corresponds well to the mean value of 41.1 mJ/m 2 obtained by the thin-layer wicking method from the penetration rates of 12 n-alkanes [29]. Moreover, it correlates well with the values of apolar interactions of silica materials evaluated by other experimental methods [30,31]. The apolar interactions of the DPPC monolayer are close to that of bare quartz; however the electron-donor interactions are significantly higher, while the electron-acceptor ones are lower than those of bare quartz.…”

Convection-enhanced water evaporation

“…Nine datasets among thirty droplets tested in this study are shown to have TI and RI simultaneously in the given field of views. The initial contact angles of water droplets on cleaned silicon wafers were 20-50 degrees, 25 which are typical for silicon wafer with angle hysteresis (∼ 10 • ) 12,25 and under laboratory humidity.…”

Influence of surface energy parameters of dental self-adhesive resin cements on bond strength to dentin

“…The advancing contact angle (Θ a ) and receding one (Θ r ) of each of three different test liquids were determined on the surfaces of the luting cements and dentin by the dynamic sessile drop method at room temperature using a contact angle measurement apparatus (OCA 15 plus, DataPhysics Instrument GmbH, Filderstadt, Germany). Although solid surface energy parameters calculated from the LWAB approach are theoretically similar irrespective of the probe liquid used, [25] Combe et al [26] clearly showed that the choice of liquid triplets remains critical even in applying the LWAB method. In this study, water (W: γ: 72.8; γ LW : 21.8; γ + : 25.5; γ À : 25.5), glycerol (G: γ: 64; γ LW : 34; γ + : 3.92; γ À : 57.4), and methylene iodide (MI: γ: 50.8; γ LW : 50.8) were used as the test liquids (all in mJ m À2 ).…”

“…The receding contact angle was then measured after sucking 2 μL from the droplet into the syringe (Figure 1). [25,29] In the LWAB approach, only the advancing contact angles were employed. [25] If the solid shows contact angle hysteresis (CAH, the difference between advancing and receding contact angles), the CAH phenomenon can be utilized to characterize the surface.…”

“…[25,29] In the LWAB approach, only the advancing contact angles were employed. [25] If the solid shows contact angle hysteresis (CAH, the difference between advancing and receding contact angles), the CAH phenomenon can be utilized to characterize the surface. [30] This study thus also employs the CAH approach, which consists of measuring both the advancing contact angle and the receding one using the same measuring liquid of a known value of γ l .…”