Surface Passivation of Silicon by Electrochemically Formed Oxide Layers

Aluminum oxide and zinc oxide coatings of automatic high precision thickness control in the range of 10-200 nm have been grown onto p-type Czochralski silicon crystalline wafers and solar cells by electrodeposition from organic electrolyte solutions at room temperature with current densities of 0.5-4 mA/cm2 within 30-120 seconds. Silicon oxide films have been formed on the surface of silicon wafers by anodic oxidation in organic electrolyte solution. Passivation effects have been investigated by means of minority carrier lifetime measurements. Silicon wafers and solar cells with formed oxides layers were exposed to a post-deposition anneal in forming gas at 300-475oC. Crystallographic structure and surface morphology of newly developed electrochemically formed coatings have been examined by X-ray diffraction and scanning electron microscopy.