High-Efficient Si Nanotextured Light-Emitting Diodes and Solar Cells With Obvious Photonic Crystal Effect

The light-emission efficiency in Si LEDs with nanoscale trench structure on the top surface can be enhanced about ten times than it in the control planer device. The photonic-crystal effect, the characteristics of the special wavelength extraction, is also observed successfully. The experimental data agree well with the theoretical surface plasma calculation. Besides, the application of nanoscale surface textured structure for the LED, the nanotextured Si solar cell is also observed and demonstrated to have the higher open-circuit voltage, short-circuit current, and optic-electric transformation efficiency, due to the more light trapping, low reflection on the nanotextured surface, and more carriers collected in the larger n-p junction area. The solar cell efficiency can be improved about 2.9% (from 12 to 14.9%) by the designed nanosurface 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 nanometer scale; even the current device structure is in the order of the micrometer scale level. High-performance Si-based optical devices make them attractive to be integrated with electronic Si chip for the future application.