Broadband near-infrared absorption enhancement in Si substrate via random distributed Ag nanoparticles

Abstract

A broadband near-infrared (NIR) absorption from 1200 to 2500 nm in Si substrate is investigated by Ag film deposition and subsequent thermal annealing. Under thermal annealing, Ag films can crack and shrink into Ag nanoparticles (NPs). Annealing temperature greatly affects the size, distribution status and morphology of Ag NPs, resulting in different NIR absorption. The influence of the size and distribution of Ag NPs on NIR absorption originated from localized surface plasmon resonance (LSPR) is theoretically simulated by a finite difference time domain method. The band width of LSPR belongs to different type Ag NPs are discussed.