Ultra-low reflectivity polycrystalline silicon surfaces formed by surface structure chemical transfer method

Abstract

A nanocrystalline Si layer can be formed by the surface structure chemical transfer (SSCT) method in which a platinum mesh is instantaneously contacted with polycrystalline Si wafers immersed in hydrogen peroxide plus hydrofluoric acid solutions. The polycrystalline Si surface after the SSCT method possesses an ultra-low reflectivity. The nanocrystalline Si layer possesses a 100–150 nm thickness, and gives a photoluminescence with a peak maximum at ∼670 nm, indicating band-gap widening. The minority carrier lifetime of as-sliced Si wafers greatly increases after the SSCT method most probably due to the enlargement of the nanocrystalline Si band-gap.

Regarding the Optical Properties of Porous Layers Prepared on Si Substrates

“…PL maximum of a black silicon layer prepared on polycrystalline Si wafer at room temperature had the position ~1.85 eV [2]. A similar method was also applied for the preparation of the BSi samples in this contribution.…”

Ultralow reflectivity surfaces by formation of nanocrystalline Si layer for crystalline Si solar cells

“…We have recently developed a method to produce low reflectivity Si surfaces by the surface structure chemical transfer (SSCT) method [10,11] in which a catalytic Pt mesh was contacted with Si immersed in an H 2 O 2 plus HF solution. The reflectivity of the Si surface is reduced to less than 3% in the 300-800 nm wavelength region.…”

“…Due to an extremely fast surface reaction, a 6 in. wafer could be treated in ∼30 s. This SSCT method formed a nanocrystalline Si layer with $150 nm thickness [11]. After the SSCT method, nitric acid oxidation of Si (NAOS) method [12] was performed to form ultrathin SiO 2 on Si nanocrystals.…”

About complex refractive index of black Si

“…The PL maximum of a black silicon layer prepared on polycrystalline Si wafer at room temperature had the position ≈ 1.85 eV, [1]. A similar method was also applied for the preparation of the BSi samples in this contribution.…”