pH值对SiC单晶表面润湿性及电学性质的影响

采用液滴捕捉技术,测量了不同pH值下SiC单晶-水界面间的三相接触角,并通过理论计算,研究了不同pH值对SiC单晶表面张力、铺展系数、表面电势和表面电荷密度的影响.结果表明,水溶液在SiC单晶表面的三相接触角随着溶液pH值的增加先增大后降低,最大接触角出现在pH 5~6之间;在强酸性和强碱性环境中, SiC单晶表面润湿性较好,尤其在强碱性环境下,其表面润湿性能最好.由理论计算可知,当pH<5时,SiC单晶表面电势和表面电荷密度为正,且其值随着溶液pH值的减少而增加;当pH>6时,SiC单晶表面电势和表面电荷密度为负,且其绝对值随着溶液pH值的增加而增加.

Influence of pH Value on Wettability and Electrical Properties of SiC Single-crystal Surface

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.