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Open Access Nano Express

Lithography-Free Fabrication of Large Area Subwavelength Antireflection Structures Using Thermally Dewetted Pt/Pd Alloy Etch Mask

Youngjae Lee1, Kisik Koh1, Hyungjoo Na1, Kwanoh Kim1, Jeong-Jin Kang2 and Jongbaeg Kim1*

Author Affiliations

1 School of Mechanical Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-Gu, Seoul, 120-749, Korea

2 Korea Institute of Industrial Technology (KITECH), Bucheon-si, Kyunggi-do, Korea

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Nanoscale Research Letters 2009, 4:364-370  doi:10.1007/s11671-009-9255-4

Published: 24 January 2009

Abstract

We have demonstrated lithography-free, simple, and large area fabrication method for subwavelength antireflection structures (SAS) to achieve low reflectance of silicon (Si) surface. Thin film of Pt/Pd alloy on a Si substrate is melted and agglomerated into hemispheric nanodots by thermal dewetting process, and the array of the nanodots is used as etch mask for reactive ion etching (RIE) to form SAS on the Si surface. Two critical parameters, the temperature of thermal dewetting processes and the duration of RIE, have been experimentally studied to achieve very low reflectance from SAS. All the SAS have well-tapered shapes that the refractive index may be changed continuously and monotonously in the direction of incident light. In the wavelength range from 350 to 1800 nm, the measured reflectance of the fabricated SAS averages out to 5%. Especially in the wavelength range from 550 to 650 nm, which falls within visible light, the measured reflectance is under 0.01%.

Keywords:
Subwavelength antireflection structure; Nanostructure; Thermal dewetting; Self-agglomeration