Design guidelines of periodic Si nanowire arrays for solar cell application

Abstract

In this letter, optimum periodic Si nanowire (SiNW) arrays are designed via simulation for solar cell application, in terms of the structural parameters, e.g., the array periodicity (P) and SiNW diameter (D). It is found that the more efficient light absorption compared to that of the Si thin film with the same thickness could be realized when P is between 250 and 1200 nm. Further, the ratio of D to P should be >0.5 (or more specifically ∼0.8) for the optimized solar energy harvesting. The underlying physics is also discussed in this work.

Modal analysis of enhanced absorption in silicon nanowire arrays

“…In addition to these single Bloch mode resonances there exist composite resonances, where energy is coupled from one absorbing mode into another through the reflection matrix R 21 . These occur as a valid solution of the continuity requirements at the top and bottom interfaces.…”

“…This is a complex task due to the interplay of a multitude of effects, which include the propagation of energy along the nanowires, diffraction by the periodic array, and Fabry-Pérot-type resonances caused by reflections off the top and bottom interfaces, all of which are strongly wavelength dependent. To date numerical investigations have used the finite-difference time-domain method (FDTD) [19], the finite element method (FEM) [20,21] and the transfer matrix method [12,22] to calculate the reflectance, transmittance and absorptance of arrays, along with the total field distributions, whilst dispersive band structures have been calculated using FDTD [12]. These are all purely numerical approaches which can require substantial computational resources, and importantly, the results of which cannot isolate the various photonic effects, allowing for only general statements about suppressed reflection, optical concentration and the excitation of guided resonance modes [12,16,21].…”

Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

“…[5][6][7][8] This study focuses on the light trapping properties of semiconductor nanowire arrays, which arise from their subwavelength features. Semiconductor nanowires and nanowire arrays can exhibit remarkable optical phenomena, such as reduced reflectance, [9][10][11] enhanced absorption, [12][13][14][15] and spectral selectivity, [16][17][18] which arise due to efficient coupling into discrete photonic modes. For individual nanowires, the photonic modes have been identified as leaky waveguide modes, 6,16 which are resonantly excited via illumination perpendicular to their axis.…”

Nanowire Applications: Thermoelectric Cooling and Energy Harvesting

“…Li et al, 2009). SiNWs are appealing choice because of their ideal interface compatibility with conventional Si-based devices.…”