Qian Yang, Magginetti David J, Jeon Seokmin, Yoon Yohan, Olsen Tony L, Wang Maoji, Gerton Jordan M, Yoon Heayoung P
Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, 84112, USA.
Materials Science and Engineering, University of Utah, Salt Lake City, UT, 84112, USA.
Sci Rep. 2020 Oct 1;10(1):16349. doi: 10.1038/s41598-020-73445-x.
Recent progress achieved in metal-assisted chemical etching (MACE) has enabled the production of high-quality micropillar arrays for various optoelectronic applications. Si micropillars produced by MACE often show a porous Si/SiO shell on crystalline pillar cores introduced by local electrochemical reactions. In this paper, we report the distinct optoelectronic characteristics of the porous Si/SiO shell correlated to their chemical compositions. Local photoluminescent (PL) images obtained with an immersion oil objective lens in confocal microscopy show a red emission peak (≈ 650 nm) along the perimeter of the pillars that is threefold stronger compared to their center. On the basis of our analysis, we find an unexpected PL increase (≈ 540 nm) at the oil/shell interface. We suggest that both PL enhancements are mainly attributed to the porous structures, a similar behavior observed in previous MACE studies. Surface potential maps simultaneously recorded with topography reveal a significantly high surface potential on the sidewalls of MACE-synthesized pillars (+ 0.5 V), which is restored to the level of planar Si control (- 0.5 V) after removing SiO in hydrofluoric acid. These distinct optoelectronic characteristics of the Si/SiO shell can be beneficial for various sensor architectures.
金属辅助化学蚀刻(MACE)取得的最新进展使得能够生产用于各种光电子应用的高质量微柱阵列。通过MACE制备的硅微柱在由局部电化学反应引入的晶体柱芯上通常会呈现出多孔的Si/SiO壳层。在本文中,我们报告了多孔Si/SiO壳层与其化学成分相关的独特光电子特性。在共聚焦显微镜下使用浸油物镜获得的局部光致发光(PL)图像显示,沿着柱体周边存在一个红色发射峰(≈650nm),其强度是柱体中心的三倍。基于我们的分析,我们发现在油/壳界面处出现了意外的PL增强(≈540nm)。我们认为这两种PL增强主要归因于多孔结构,这与之前的MACE研究中观察到的行为类似。与形貌同时记录的表面电位图显示,MACE合成柱体的侧壁上具有显著较高的表面电位(+0.5V),在氢氟酸中去除SiO后恢复到平面硅对照的水平(-0.5V)。Si/SiO壳层的这些独特光电子特性可能对各种传感器架构有益。