Reactive Ion Etching Texturing for Multicrystalline Silicon Solar Cells Using a SF₆/O₂/Cl₂Gas Mixture

Abstract

Maskless random reactive ion etching (RIE) texturing employing a SF6/O2/Cl2 gas mixture was investigated in order to achieve higher efficiencies in multicrystalline silicon (mc-Si) solar cells. Triangular pyramid structures with an aspect ratio of 1 were formed and, when the RIE power increased, the average reflectance was reduced by about 1.46% per 10 W. This was due to the increased density of the surface features. The performances of all of the RIE-textured mc-Si solar cells were improved compared with that of the reference cell. Among them, the 110 W cell, which had a 0.6% higher efficiency than the reference cell, had the highest efficiency of 16.82%. An impedance analysis was carried out to determine series resistance (R s), shunt resistance (R sh), and junction capacitance (C j). Interestingly, the cell with higher efficiencies and higher structure densities had higher linear reverse currents.

Plasma nanotexturing of silicon surfaces for photovoltaics applications: influence of initial surface finish on the evolution of topographical and optical properties

“…Indeed, RIE processing of silicon induces defects such as impurities or vacancies [43] that will degrade the surface passivation level and, in turn, the open-circuit voltage of the cell [42]. In order to achieve good passivation, though, a damage removal etching subsequent to nanotexturing might be applied [14,44], which will also improve the short wavelength response of the solar cell, since these wavelengths are absorbed at very shallow depths [45]. However, this additional step usually also induces a recovery of the reflectance over the entire solar spectrum due to a smoothing of the nanostructures.…”

Atomic force microscopy studies of formation of black silicon by reactive ion etching

“…The gases are supplied from the edge of the upper electrode. 31 The RIE process can provide high rates of isotropic etching, which makes it possible to vary the etch directionality between isotropic and anisotropic etching using SF 6 /O 2 at various flow rates. 32 In SF 6 /O 2 /CHF 3 plasma, each gas has its specific function and influence.…”