Periodic Nanostructured Thin-Film Solar Cells

Abstract

Si-based photonic crystal device such as solar cells have been developed and attract lots of attention. Whether what kind of different structures are used, two key problems are needed to investigate. One is the improvement of the optic-electric (or electric-optic) transformation efficiency. Another is the capability to modulate the light-emitting and detection wavelength for various industrial applications. The wavelength of the light emission and detection can also be further adjusted by changing the material band-gap. In this work, we develop the periodic nanoscale surface textured solar cells. The characteristics of top thin film textured solar cells is developed and estimated to see if the structure is worthy to be scaled from the modern micrometer (um) level down to the nanometer (nm) level continuously. The process of nm-scale textured Si optoelectronic device used in this work is fully comparable to the modern CMOS industry. Optimal Ge concentration in SiGe-based solar cells has been investigated qualitatively by the systemic experiments. With the appropriate addition of Ge to a SiGe-based solar cell, the short current density (Isc) is successfully increased without affecting the open-circuit voltage (Voc) and then the overall efficiency is successfully improved about 4 % than the nanoscale surface textured Si solar cell.