Enhancing light trapping of macroporous silicon by alkaline etching: application for the fabrication of black Si nanospike arrays

Abstract

ABSTRACT:The synthesis of highly absorbing silicon (black Si (BSi)) is a very active research topic with promising applications in the field of sustainable energies, ultrasensitive sensing and antibacterial materials. Here, we show that extended alkaline etching of macroporous Si, fabricated by photoelectrochemical etching drastically influence the surface structures as well as their optical properties. We demonstrate that this treatment can considerably improve the light trapping of the surface and we finally show that it is possible to use it for fabricating very quickly highly-absorbing arrays of sharp and crystalline BSi nanospikes (NSpikes).

Black Silicon Photoanodes Entirely Prepared with Abundant Materials by Low-Cost Wet Methods

“…First, n-type Si(100) wafers were structured by employing a rapid (<10 min) two-step method previously introduced by our group to fabricate a ~10 m-thick porous Si layer (Figure 1a) composed of vertically-aligned macropores bearing (Figure 1b). As previously reported, 23 these structures efficiently trap the incident light, as shown by their pitch-black visual appearance and their low reflectance (vide infra), we refer herein to them as BSi. Next, we modified the BSi surfaces with a catalytic and stabilizing coating.…”

Electrochemiluminescence with semiconductor (nano)materials

“…From an optical point of view, improved light absorption can be induced for nano-and microstructured SC by multiple internal reections or a smooth transition of refractive index, respectively. [117][118][119] Besides, the main advantage of using a structured photoelectrode compared to a planar is that it allows decoupling light absorption and carrier collection. 120 For instance, for SCs suffering from a short minority carrier diffusion length like oxides, using a structure with features smaller than the diffusion length (typically z5 nm for h + in a-Fe 2 O 3 ) can decrease recombination losses.…”

Silicon Photoelectrodes Prepared by Low-Cost Wet Methods for Solar Photoelectrocatalysis

“…To assess the versatility of our preparation strategies on different n-Si substrates and to determine if the photoanode performance could be further improved by enhanced photon absorption, the electrodeposition of transition metals was investigated on structured Si absorbers. 3 BSi, composed of an array of highly absorbing Si spikes prepared via a simple wet procedure (Figure 1c), 5 was used as the electrode substrate. It was modified by electrodepositing Ni-NiFe core−shell NPs (Figure 7a) by a two-step electrodeposition method.…”