High efficient Si nano-textured light-emitting diodes and solar cells with obvious photonic crystal effect

The light-emission efficiency in Si light-emitting diodes with nano-scale trench structure on the top surface can be enhanced about 10 times than it in the control device. The photonic crystal effect, the characteristics of the wavelength extraction, is also observed easily and it agrees well with the theoretical surface plasma calculation. In addition to the application of nano-scale textured surface structure for the light-emitting diode, the nano-textured surface Si solar cell is also observed and investigated to have the higher open-circuit voltage, short circuit current, and optic-electric transformation efficiency, due to the light trapping, low reflection on the nano-textured surface, and more carriers collected in the larger n/p junction area. The efficiency can successfully be improved about 2.9% (from 12% to 14.9%) by the nano-surface structure. These experimental results prove that the dimension of the surface structure on the Si photonic device is worthy to continuously scale down to the nano-meter scale; even the current device structure is in the order of the micro-meter scale level.