Growth of TiO ₂ anti-reflection layer on textured Si (100) wafer substrate by metal-organic chemical vapor deposition method

Recently anti-reflective films (AR) have been intensely studied. Particularly for textured silicon solar cells, the AR films can further reduce the reflection of the incident light through trapping the incident light into the cells. In this work, TiO ₂ anti-reflection films have been grown on the textured Si (100) substrate which is processed in two steps, and the films are deposited using metal-organic chemical vapor deposition (MOCVD) with a precursor of titanium tetra-isopropoxide (TTIP). The effect of the substrate texture and the growth conditions of TiO ₂ films on the reflectance has been investigated. Pyramid size of textured silicon had approximately 2-9 μm. A well-textured silicon surface can lower the reflectance to 10%. For more reduced reflection, TiO ₂ anti-reflection films on the textured silicon were deposited at 600 °C using titanium tetra-isopropoxide (TTIP) as a precursor by metal-organic chemical vapor deposition (MOCVD), and the deposited TiO ₂ layers were then treated by annealing for 2 h in air at 600 and 1000 °C, respectively. In this process, the treated samples by annealing showed anatase and rutile phases, respectively. The thickness of TiO ₂ films was about 75±5 nm. The reflectance at specific wavelength can be reduced to 3% in optimum layer.