Optimization of nano-grating structure to reduce the reflection losses in gaas solar cells

In this paper, finite-difference time domain (FDTD) method is used to simulate the reflection losses of subwavelength grating (SWG) structure in GaAs solar cells. The SWG structures make an excellent alternative antireflective (AR) coating due to its capacity to reduce the reflection losses in GaAs solar cells. The SWG structures allow the gradual change in refractive index that confirm excellent AR and light trapping properties, when compare with planar thin film structures. The nanorod (nano-grating) structure acts as a single layer AR coating, whereas the triangular (conical or perfect cone) and parabolic (or truncated cone) shaped grating structures act as a multilayer AR coating. Simulation results show that the reflection loss of triangular (conical or perfect cone) shaped nano-grating structure having a 300 nm grating height and a 830 nm period is ~2%, which is about 28% less than that of flat type substrates.