Gallium indium eutectic masking prior to porous silicon formation creates unique spatially-dependent chemistries

• Published in: Analytica chimica acta 2018-11, Vol.1032, p.147-153
• Main Authors: Collado, Crystal M., Horner, Ian J., Empey, Jennifer M., Nguyen, Lisa N.Q., Bright, Frank V.
• Format: Article
• Language: English
• Subjects: Correlation analysis; Emission analysis; Eutectics; Fabrication; Fourier transforms; Gallium; Gallium indium eutectic; Gaseous analyte response; Indium; Luminescence; Masking; Organic chemistry; Oxidation; Photoluminescence; Photons; Porosity; Porous silicon; Scanning electron microscopy; Silicon; Spatially-dependent chemistries; Spatially-dependent response
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2018.05.052

We demonstrate that gallium indium (GaIn) eutectic can be used to create interesting crystalline Si/porous silicon (cSi/pSi) platforms that exhibit unique analyte- and spatially-dependent photoluminescence (PL) responses. Here we characterize these cSi/pSi regions by using profilometry, scanning electron microscopy (SEM), wide-field PL microscopy, and Fourier transform infrared (FTIR) microscopy. As we move along a vector from the cSi/pSi interface out into “bulk” pSi, the: (i) analyte-dependent, PL-based response initially increases and then decreases; (ii) total PL emission intensity, in the absence of analyte, increases; (iii) pSi thickness increases; and (iv) relative O2Si-H to Si-H band amplitude ratio decreases. Thus, the analyte-dependent PL response magnitude is correlated to the extent of pSi oxidation; which can be easily controlled by using GaIn eutectic as a mask during the pSi fabrication process. [Display omitted] •Unique porous silicon (pSi) microarrays can be created by using GaIn masks.•Array elements show analyte- and spatially-dependent responses.•The relative O2Si-H to Si-H band amplitude ratio is spatially dependent.•Responses arise from competition between analytes and different pSi surface sites.