Studies of porous semiconducting materials and their applications in nanotechnology

Hee Cheul Choi, Purdue University

Abstract

In this thesis, a variety of studies about the effect of organic monolayers on the light emitting properties of porous silicon (PS), electrochemical applications for the preparation and patterning of porous semiconducting materials such as PS, porous germanium (PG), and semiconducting metal oxides (ZnO, CeO, Cr2O3) are described. A simple technique for preparation of noble metal nanoparticles is also developed. The PS samples functionalized with alkynes or alkenes by various reaction techniques show improved light emitting properties with increased lifetimes. The other important effect of functionalization of PS surface on ECL is to decrease the induction time. For the PS functionalized by anodic electrografting (AEG) recycles ECL about 10 times by applying a brief 10 s of a cathodic bias. It is also remarkable that PG, PS's congener, has been prepared by a novel bipolar electrochemical etching (BEE) technique from an ethanolic HCl electrolyte system. Both positive and negative microscale patterns of semiconducting metal oxides are efficiently and rapidly prepared on flat Si (100) surfaces via a simple photo-assisted bipolar electrochemical process. Selective crystallization of three different metal oxides, ZnO, CeO2, or Cr2O 3 can be achieved in a straightforward manner by a short (5 s) anodic current prior to the cathodic electrodeposition with illumination through a photomask. Lastly, a new technique for preparation of noble metal nanoparticles on semiconducting (Ge) or metallic (Cu, Al, In, Sn, Zr, Zn) surfaces is developed. Redox-derived electroless deposition process is combined with nanolithography techniques, such as dip-pen nanolithography or soft lithography (μ-CP, micro-contact printing), to prepare nanoarchitectures.

Degree

Ph.D.

Advisors

Buriak, Purdue University.

Subject Area

Chemistry

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