Preparation And Wetting Of Porous Silicon

The wetting of liquid on solid and interfacial interaction between liquid and solid metal usually occur in the material fabrication and processing, which decide the possibility of material fabrication and properties. The wetting of mercury on Si was chosen as the research object in this thesis. The research work mainly contains the following aspects:This thesis utilizes electrochemical etching technology to prepare the strip and pillar ordered porous silicon array on the n-type <100> Si substrate. Influence of the hydrofluoric acid concentration of electrolytic solution, etching current density and etching time on the depth and surface morphology of ordered porous silicon array was studied. Ordered porous silicon array on the n-type <100> Si substrate was prepared.Electrowetting of mercury on flat Si substrate which was covered different thickness SiO2 was studied by sessile drop method under room temperature. The research results showed that with increase of supplied voltage the contact angle between mercury and flat Si substrate was reduced gradually at the initial applied voltage stage. When the supplied voltage reached the certain critical voltage, the contact angle saturation phenomenon will be appear. The contact angle would not change when the supplied voltage was increased. The critical voltage for contact angle saturation was related to the thickness of dielectric layer on flat silicon substrate. The critical voltage was increased gradually with the dielectric layer thickness. A greater supplied voltage is required for a thicker dielectric layer substrate in order to reach the same contact angle. These experimental phenomena were analyzed by combination of the electrowetting mechanism with the property of silicon.Electrowetting of mercury on porous silicon substrate which was covered SiO2 was studied by sessile drop method under room temperature. The research results showed that the apparent contact angle of mercury on porous silicon substrate is greater than that of mercury on flat silicon substrate. In the same voltage change, the change range of the apparent contact angle of mercury on porous silicon increases with the depth of porous silicon.