Optical Function of Black Silicon

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K04974
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Nanostructural chemistry
• Research Institution: Osaka City University
• Principal Investigator: Tsuboi Yasuyuki 大阪市立大学, 大学院理学研究科, 教授 (00283698)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 光ピンセット / 光圧 / 蛍光顕微鏡 / 微粒子 / ナノ粒子 / プラズモン

Outline of Final Research Achievements

We present various modes of operation of optical tweezers (OT) using Si. Peculiarities of optical trapping of polymer beads of different sizes on a flat crystalline Si (F-Si) and nanostructured Si (black Si, B-Si) were investigated at laser wavelength λ = 808 and 1064 nm. Black Si surface can enhance an optical force to grip nanoparticles and dramatically change the trapping behavior. Different modes of OT were realized by changing nature of Si surface (flat v.s. nanotextured), wavelength λ, laser irradiation intensity I, and irradiation area. Namely, OT for (i) - a single particle trapping by tightly (I ~ MW/cm2) and loosely (kW/cm2) focused irradiation on F-Si, (ii) - a large-number of 3D trapped beads by a tightly focused irradiation (I ~ MW/cm2) on B-Si, (iii) - small number of particles trapped at I ~ kW/cm2 on F-Si, and (iv) - large number of particles trapped at I ~ kW/cm2 on B-Si resulting in a 2D self-ordered assembly. The OT mechanisms of these 4 modes are analyzed.

Free Research Field

基礎物理化学

Academic Significance and Societal Importance of the Research Achievements

これまで光機能材料として系統的な研究がなされてこなかった物質系といえるブラックシリコンを、プラズモニクス同様に光ピンセットや光化学反応系という、物理、化学の両側面からその機能を追求しようという点が特色であり、そのようなアプローチは未だない。
プラズモニクスを司る貴金属ナノ構造と違い、安価、高速、大面積、容易な方法でブラックシリコンは作製できる。よって、その光学機能を十分解明すれば、応用上の意義は非常に大きい。