Recent improvement of silicon absorption in opto-electric devices

Abstract

Silicon dominates the contemporary electronic industry. However, being an indirect band-gap material, it is a poor absorber of light, which decreases the efficiency of Si-based photodetectors and photovoltaic devices. This review highlights recent studies performed towards improving the optical absorption of Si. A summary of recent theoretical approaches based on the first principle calculation has been provided. It is followed by an overview of recent experimental approaches including scattering, plasmon, hot electron, and near-field effects. The article concludes with a perspective on the future research direction of Si-based photodetectors and photovoltaic devices.

Improvement of Plasmonic CuS Nanocrystals’ Optoelectronic Properties via Cation Exchange for Infrared Detection Enhancement

“…Therefore, excitation efficiency is low in devices. Optical near-field (ONF) is a large localized electrical field generated at the nanoscale around plasmonic materials, irradiated by propagating light. , The generated ONF component is highly non-uniform in space, leading to the existence of Fourier components with large wave numbers (Δ k ) that are 2 to 3 orders of magnitude larger than those of the propagating light (based on numerical calculations) . Although plasmon excitation can generate a large value of Δ k , Noda et al revealed that a large Δ k can be generated by field confinement only, without plasmon excitation .…”

“…To illustrate the application of the as-produced NCs in optical devices, electronic properties of NCs in a lateral photodetector device configuration were investigated. The photodetector working mechanisms based on the two samples along with their results can be considered as follows: (1) Lightly cation-exchanged NCs: Due to the indirect band gap of the parent CuS NCs and the illuminated wavelength range opposite to the plasmon resonance of NCs, the dominant mechanism for increased photo-response is the direct excitation in the indirect band gap semiconductor via an optical near-field (ONF) effect, while low concentrations of Pb 2+ cations act as an electron acceptor and charge separation occurs. ,, (2) Hetero-structured NCs: Charge separation is hinted by constructing band alignment in the Cu 2– x S/PbS nano-hetero-structure and conversion of excitons to free charge carriers. , …”

Silicon-Au nanowire resonators for high-Q multiband near-infrared wave absorption

“…The photonic Mie resonances in dielectric materials including semiconductors are formed by the displacement currents rather than the actual currents, which leads to a much lower loss than that in the metallic resonators. Recently, intense light absorption has been realized in the semiconductors [15][16][17], which paves a new way for high-performance optoelectronic device and applications [18,19]. Broadband perfect absorption, which is useful for photovoltaics, has also been demonstrated in the semiconductor resonators including the particles and the ultrathin films [20][21][22][23].…”