Chemistry, Physics and Technology of Surface

ISSN 2518-1238 (Online), ISSN 2079-1704 (Print)

The purpose of this article is to present theoretical calculations of the optical spectra of periodic silicon nanostructures dependent on their length. For calculations, the structure with silicon nanowires with a constant diameter and period was simulated. The diameter of the nanowires is 80 nm, and the structure period is 100 nm. The dependence of absorption, reflection and transmission spectra on the length of nanowires (500–5000 nm) was investigated. For theoretical studies, the Maxwell equation was solved by the finite difference method in the time domain (FDTD). This method can be applied precisely to general electromagnetic structures, including free-form particles. The advantage of this method is the simplicity and the capability to obtain results for a wide range of wavelengths in single calculation, as well as the capability to specify the properties of materials at any point of the calculation grid, which allows us to consider anisotropic, dispersive and nonlinear environments. At the same time, the FDTD method can be very resource-intensive, especially when simulating complex structures. This method requires from 10 to 30 points per wavelength, and small wavelengths determine the very high sampling frequency. This leads to cumbersome calculations, especially in three dimensions. To simplify calculations, the problem was carried out in two-dimensional form. It is shown that for these parameters of the structure, the reflection coefficient does not depend on the length of the nanowires, although by 30 % it is smaller than that in the solid silicon plate. The transmission coefficient decreases with the increase in the length of the nanowires, although at all calculated wavelengths it remains higher than that in the silicon wafer. It is shown that in the visible region of the spectrum, the absorption coefficient is significantly higher and with the increase of the length of nanowires, an expansion of absorption spectra is observed, indicating an increase in the absorption range of sunlight. It is shown that the use of silicon nanostructures as solar cells is an important and perspective direction of research.

1. Hongzhe W., Zixu S., Weiqiang H., Junshuai L., Jichun Ye. Efficient light trapping in low aspect-ratio honeycomb nanobowl surface texturing for crystalline silicon solar cell applications. Appl. Phys. Lett. 2013. 103(25): 153105. https://doi.org/10.1063/1.4851236

2. Hua B., Xiulin R. Optical absorption enhancement in disordered vertical silicon nanowire arrays for photovoltaic applications. Opt. Lett. 2010. 35(20): 3378. https://doi.org/10.1364/OL.35.003378

3. Wenbo S., Qiang F., Zhizhang C. Finite-difference time-domain solution of light scattering by dielectric particles with a perfectly matched layer absorbing boundary condition. Appl. Optics. 1999. 38(15): 3141. https://doi.org/10.1364/AO.38.003141

4. Sullivan D., Liu J., Kuzyk M. Three-dimensional optical pulse simulation using the FDTD method. IEEE transactions on microwave theory and techniques. 2000. 48(7): 1127. https://doi.org/10.1109/22.848495

5. Taflove A., Hagness S.C. Computational Electrodynamics: the finite-difference time-domain method. 2nd ed. (Boston, Ma: Artech House, 2000).

6. Hirigoyen F., Crocherie A., Vaillant J., Cazaux Y. FDTD-based optical simulations methodology for CMOS image sensor pixels architecture and process optimization. SPIE-IS&T. 2008. 6816: 681609-1. https://doi.org/10.1117/12.766391

7. Bogolubov A.N., Belokopytov G.V., Dombrovskaya Z.O. Modelling of spectral dependencies for 2D photonic crystal waveguide systems. Moscow University Physics Bulletin. 2013. 5: 8. [in Russian]. https://doi.org/10.3103/S0027134913050044

8. Deinega A., Valuevb I. Long-time behavior of PML absorbing boundaries for layered periodic structures. Computer Physics Communications. 2011. 182(1): 149. https://doi.org/10.1016/j.cpc.2010.06.006

9. Pylypova O.V., Evtukh A.A., Parfenyuk P.V., Korobchuk I.M., Havryliuk O.O., Semchuk O.Yu. Influence of Si nanowires on solar cell properties: effect of the temperature. Appl. Phys. A. 2018. 124(11): 773. https://doi.org/10.1007/s00339-018-2200-6

10. Li J., Yu H.Yu., Wong S.M., Zhang G., Sun X., Lo P.G.Q., Kwong D.L. Si nanopillar array optimization on Si thin films for solar energy harvesting. Appl. Phys. Lett. 2009. 95(3): 033102. https://doi.org/10.1063/1.3186046

11. Li J., Wong S.M., Li Y., Yu H.Yu. High-efficiency crystalline Si thin film solar cells with Si nanopillar array textured surfaces. In: 35th IEEE Photovoltaic Specialists Conference. 2010. https://doi.org/10.1109/PVSC.2010.5614445. https://doi.org/10.1109/PVSC.2010.5614445

12. Li J., Yu H. Yu., Li Y., Wang F., Yang M., Wong S.M. Low aspect-ratio hemispherical nanopit surface texturing for enhancing light absorption in crystalline Si thin film-based solar cells. Appl. Phys. Lett. 2011. 98(2): 021905. https://doi.org/10.1063/1.3537810

13. Garnett E.C., Brongersma M.L., Cui Y., McGehee M.D. Nanowire Solar Cells. Annu. Rev. Mater. Res. 2011. 41: 269. https://doi.org/10.1146/annurev-matsci-062910-100434

14. Hu L., Chen G. Analysis of optical absorption in silicon nanowire arrays for photovoltaic applications. Nano Lett. 2007. 7(11): 3249. https://doi.org/10.1021/nl071018b

15. Avakyants L.P., Bokov P.Yu., Chervyakov A.V., Chuyas A.V., Yunovich A.E., Vasileva E.D., Bauman D.A., Uelin V.V., Yavich B.S. Interference effects in the electroreflectance and electroluminescence spectra of InGaN/AlGaN/GaN light-emitting-diode heterostructures. Semiconductors. 2010. 44(8): 1090. https://doi.org/10.1134/S1063782610080245

16. Sturmberg B.C.P., Dossou K.B., Botten L.C., Asatryan A.A., Poulton C.G., de Sterke C.M., McPhedran R.C. Modal analysis of enhanced absorption in silicon nanowire arrays. Opt. Express. 2011. 19(S5): A1067. https://doi.org/10.1364/OE.19.0A1067