4. Fabrication of Nano-Pyramid Array (NPA) and Control of Its Surface Potential
We have produced a simple process to fabricate nanopyramid arrays (NPAs) on Si surface (Fig.1). This process uses combination of two etching phenomena, that is, the enhanced etching of ion-exposed SiO2 in HF and the retarded etching of ion-exposed Si in hydrazine.
First, we reported relationship between the ion dose and the etch rate of Si in hydrazine (Fig.2).The etch rate retardation occurs independently of ion type or Si type.
Next, We reported fabrication of convex Nano-Pyramid Array (cNPA). Ions are implanted onto a Si substrate through the patterned resist mask, after the convex nanopyramids are fabricated under the damaged region mask by dipping in hydrazine(Fig.3).
And this process enables us to easily fabrication a p-n junction in the apex of the nanopyramid. Because we report the electrical properties the Nanopyramid sing Scanning Maxwell-stress microscopy (SMM).
We observed phosphorus ion implantation into p-type Si and etching (which is called gn-on-p-typeh in this page; and BF2 ion implantation into n-type named gp-on-n typeh) by SMM. Fig4.(b) is SMM topographical images of n-on-p-type, Fig.4(c) is SMM surface potential images of n-on-p-type and Fig.4(d) is SMM surface potential images of p-on-n-type. In this case, the topographical images of the topsithis part seems to the region of white colorjmeans apex of the nanopyramid. And surface potential images of the tops (this part seems to the region of white color) means that positively charged donor ions exists there of p-on-n-type, and acceptor ions exists there of n-on-p-type. These two regions are agreements. This result means apex of p-on-n type nanopyramid charged donor ions exists.
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2002/01/24 webmasters@coe.waseda.ac.jp