Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting.

Qiang Li,Kening Mao,Ding Zhao,Xu Fang,Hui Ye,Kaikai Du,Min Qiu

doi:10.1038/srep29195

Abstract

A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis.

Highlights

To explore the enhanced transmission based on strong interference dominated by interface phase shift in planar metal/semiconductor double-layered films, Si layers with thicknesses of [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25] nm (in a 5 nm increment) on 30-nm-thick Ag layers are fabricated and experimental transmission at normal incidence in the visible range
Amorphous silicon (a-Si) and Ag are used as semiconductor and metal materials, respectively
The amorphous silicon (a-Si) is highly absorbing at visible frequencies owing to direct electronic transitions at energies above the absorption edge

Summary

Introduction

To explore the enhanced transmission based on strong interference dominated by interface phase shift in planar metal/semiconductor double-layered films, Si layers with thicknesses of [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25] nm (in a 5 nm increment) on 30-nm-thick Ag layers are fabricated and experimental transmission at normal incidence in the visible range

Results

Conclusion