PASSIVATION OF SILICON SOLAR CELLS VIA LOW TEMPERATURE WET CHEMICAL OXIDATION

In the development of high efficiency crystalline Si solar cells, decreasing bulk and surface recombination velocities of the minority carriers is vital. As the bulk recombination could be suppressed by enhancing the material quality, the effect of surface recombination on cell performance becomes more dominant. Also, recent studies have revealed that the area under the metal contacted region needs to be passivated to minimize the carrier recombination. The passivation of front and back surface of the cell can be achieved using different techniques and materials. Dry oxidation is a well-known process by the industry and requires high temperature treatment that increases thermal budget of the whole fabrication sequence and also degrades bulk lifetime. For this reason, a low temperature technique like wet chemical oxidation is highly desirable for the growth of thin oxide layers. In this work, 4 different wet chemical oxidation techniques based on nitric acid (HNO3), hydrogen peroxide (H2O2), RCA II (HCl: H2O2) and hydrochloric acid (HCl) solutions were studied and corresponding cell performances was compared with that of dry oxidation