Abstract: The three-phase contact angle on SiC wafer/water interface was measured under different pH values using the goniometric technique.Furthermore, the influence of different pH value on surface tension, spreading coefficient, surface potential and surface charge density at the SiC wafer/water interface were investigated by theoretical calculation.The results demonstrate that the three-phase contact angle on SiC wafer/water interface increase first and then decrease with the increase in pH value.The maximum contact angle is found around pH 5-6.The wettability of SiC wafer/water interface is better in strong acid or base environment than in mild conditions, especially in strong base conditions.According to the theoretical calculation, the surface potential and surface charge density of the SiC wafer appeare positive and decrease with the increasing pH value when the pH value is below 5, while they show negative and the absolute value increase with the increasing pH value when the pH value is ablove 6.

Key words: The three-phase contact angle on SiC wafer/water interface was measured under different pH values using the goniometric technique.Furthermore, the influence of different pH value on surface tension, spreading coefficient, surface potential and surface charge density at the SiC wafer/water interface were investigated by theoretical calculation.The results demonstrate that the three-phase contact angle on SiC wafer/water interface increase first and then decrease with the increase in pH value.The maximum contact angle is found around pH 5-6.The wettability of SiC wafer/water interface is better in strong acid or base environment than in mild conditions, especially in strong base conditions.According to the theoretical calculation, the surface potential and surface charge density of the SiC wafer appeare positive and decrease with the increasing pH value when the pH value is below 5, while they show negative and the absolute value increase with the increasing pH value when the pH value is ablove 6.