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Figure 1 | Nanoscale Research Letters

Figure 1

From: Superparamagnetic iron oxide nanoparticle attachment on array of micro test tubes and microbeakers formed on p-type silicon substrate for biosensor applications

Figure 1

Top-view SEM images of macroporous Si formed on p-type substrate with different formation parameters. (a) random, wide, and connected porous structure formed on 0.1 to 0.5-Ω-cm wafer with J = 2 mA/cm2, t = 30 min and HF/DMF ratio = 1:11; (b) hexagonal, honey-comb type pore structure with narrow pore walls formed on 2 to 5-Ω-cm resistivity wafer using J = 3 mA/cm2, t = 60 min and HF/DMF ratio = 1:10; (c) more-or-less regular and circular macropores on 10-Ω-cm wafer formed with J = 5 mA/cm2, t = 60 min and HF/DMF ratio = 1:9; (d) widely separated pores formed with the same formation parameters as in (c) but on a 100-Ω-cm wafer; and (e) shows the formation of cracks without any resolvable porous structure for 0.01 to 0.05-Ω-cm wafer.

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