Open Access Nano Express

Bimetallic non-alloyed NPs for improving the broadband optical absorption of thin amorphous silicon substrates

Chee Leong Tan1, Sung Jun Jang2, Young Min Song24, Kamal Alameh3 and Yong Tak Lee12*

Author Affiliations

1 Advance Photonic Research Institute, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea

2 School of Information and Communications, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea

3 Electron Science Research Institute, Edith Cowan University, 270 Joondalup Dr, Joondalup WA 6027, Australia

4 Department of Electronics Engineering, Pusan National University, Busandaehak-ro, 63beon-gil, Geumjeong-gu, Busan 609-735, Republic of Korea

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Nanoscale Research Letters 2014, 9:181  doi:10.1186/1556-276X-9-181

Published: 13 April 2014

Abstract

We propose the use of bimetallic non-alloyed nanoparticles (BNNPs) to improve the broadband optical absorption of thin amorphous silicon substrates. Isolated bimetallic NPs with uniform size distribution on glass and silicon are obtained by depositing a 10-nm Au film and annealing it at 600°C; this is followed by an 8-nm Ag film annealed at 400°C. We experimentally demonstrate that the deposition of gold (Au)-silver (Ag) bimetallic non-alloyed NPs (BNNPs) on a thin amorphous silicon (a-Si) film increases the film's average absorption and forward scattering over a broad spectrum, thus significantly reducing its total reflection performance. Experimental results show that Au-Ag BNNPs fabricated on a glass substrate exhibit resonant peaks at 437 and 540 nm and a 14-fold increase in average forward scattering over the wavelength range of 300 to 1,100 nm in comparison with bare glass. When deposited on a 100-nm-thin a-Si film, Au-Ag BNNPs increase the average absorption and forward scattering by 19.6% and 95.9% compared to those values for Au NPs on thin a-Si and plain a-Si without MNPs, respectively, over the 300- to 1,100-nm range.

Keywords:
Optics at surface; Surface plasmon resonance; Antireflection; Scattering light