Highly Efficient Silicon Nanowire Surface Passivation by Bismuth Nano-Coating for Multifunctional Bi@SiNWs Heterostructures

Abstract

A key requirement for the development of highly efficient silicon nanowires (SiNWs) for use in various kinds of cutting-edge applications is the outstanding passivation of their surfaces. In this vein, we report on a superior passivation of a SiNWs surface by bismuth nano-coating (BiNC) for the first time. A metal-assisted chemical etching technique was used to produce the SiNW arrays, while the BiNCs were anchored on the NWs through thermal evaporation. The systematic studies by Scanning Electron Microscopy (SEM), energy dispersive X-ray spectra (EDX), and Fourier Transform Infra-Red (FTIR) spectroscopies highlight the successful decoration of SiNWs by BiNC. The photoluminescence (PL) emission properties of the samples were studied in the visible and near-infrared (NIR) spectral range. Interestingly, nine-fold visible PL enhancement and NIR broadband emission were recorded for the Bi-modified SiNWs. To our best knowledge, this is the first observation of NIR luminescence from Bi-coated SiNWs (Bi@SiNWs), and thus sheds light on a new family of Bi-doped materials operating in the NIR and covering the important telecommunication wavelengths. Excellent anti-reflectance abilities of ~10% and 8% are observed for pure SiNWs and Bi@SiNWs, respectively, as compared to the Si wafer (50–90%). A large decrease in the recombination activities is also obtained from Bi@SiNWs heterostructures. The reasons behind the superior improvement of the Bi@SiNWs performance are discussed in detail. The findings demonstrate the effectiveness of Bi as a novel surface passivation coating, where Bi@SiNWs heterostructures are very promising and multifunctional for photovoltaics, optoelectronics, and telecommunications.

Guided CdTe Nanowires Integrated into Fast Near-Infrared Photodetectors

“…To that we can also add a passivation effect of the surface states by the Bi thin films deposited on the NWs as shown in Figure . A similar passivation effect was previously shown in a paper by Naffeti et al for Si NWs, decorated by Bi nanocrystals . This study demonstrated that the deposition of Bi nanocrystals on top of Si NWs induces a synergetic effect, augmenting the optical properties of the NWs.…”

“…A similar passivation effect was previously shown in a paper by Naffeti et al for Si NWs, decorated by Bi nanocrystals. 61 This study demonstrated that the deposition of Bi nanocrystals on top of Si NWs induces a synergetic effect, augmenting the optical properties of the NWs. The Bi coverage serves a dual purpose, acting both as a surface passivation agent and as an effective antireflector coating.…”

Structure and electrical behavior of silicon nanowires prepared by MACE process

“…Recently, it was shown that MACE-produced SiNW arrays are covered with porous structures, silicon nanocrystals, which result from the lateral etching of NWs sidewalls. The broad PL spectrum centered at 695 nm (1.78 eV) is attributed to radiative recombination of excitons in these nanocrystals [29]. In our experiment, even if the length of the NWs does not differ very much, the PL intensity is substantially higher in the case of long wires which suggests the formation of a larger number of luminescence centers.…”

Improvement of the Electrical Performance of Ag/MEH-PPV/SiNWs Schottky Diode by the Insertion of a Thin Layer of MEH-PPV Polymer and Study of the Annealing Effect

“…Organic electronics have recently experienced relentless interest [5,6]. In order to improve the performance of SiNWs and integrating it into the field of organic electronics, research efforts have focused on the passivation process by depositing layers acting as a barrier with the external environment [7,8]. Conjugated polymers are materials of great interest in photovoltaic, organic electronics and optoelectronic devices [9][10][11].…”