University of Kentucky
Tailoring Porous Alumina Templates for Use in Nano-Scale Heterojunctions
Institution
University of Kentucky
Faculty Advisor/ Mentor
Vijay Singh
Abstract
Thin-film anodized porous alumina templates have the potential for revolutionary impact in nano-structured solar cells and display devices. They can be used to create large, uniform, self-ordered nanoscale hetero-junctions. Aluminum anodized in a suitable acidic electrolyte under controlled conditions forms a hydrated aluminum oxide containing a two-dimensional hexagonal array of cylindrical pores. Electrodeposition of subsequent materials in the pores leads to the formation of individual devices, each isolated from the other by the insulating alumina matrix around it. Evaporative deposition may also be possible with thin porous alumina and lower aspect ratio. The advantages of this method are (1) uniform pores with sub-micrometer to nanometer diameters, (2) arrangement of vertically directed pores at almost identical spacing, (3) ability to control diameter of pores by changing electrolyte composition and electrochemical processing regimes, and (4) high reproducibility of the film structure for samples of large sizes. The challenges for our application are to tailor the thickness of the film to the desired solar cell. We are also working to determine whether an aluminum contact layer attached to the pores is a desirable attribute. Anodization of porous alumina has been performed at different temperatures and for different durations. Characterization has been done by FE-SEM, UV-Vis Spectrophotometer and 4-point probe.
Tailoring Porous Alumina Templates for Use in Nano-Scale Heterojunctions
Thin-film anodized porous alumina templates have the potential for revolutionary impact in nano-structured solar cells and display devices. They can be used to create large, uniform, self-ordered nanoscale hetero-junctions. Aluminum anodized in a suitable acidic electrolyte under controlled conditions forms a hydrated aluminum oxide containing a two-dimensional hexagonal array of cylindrical pores. Electrodeposition of subsequent materials in the pores leads to the formation of individual devices, each isolated from the other by the insulating alumina matrix around it. Evaporative deposition may also be possible with thin porous alumina and lower aspect ratio. The advantages of this method are (1) uniform pores with sub-micrometer to nanometer diameters, (2) arrangement of vertically directed pores at almost identical spacing, (3) ability to control diameter of pores by changing electrolyte composition and electrochemical processing regimes, and (4) high reproducibility of the film structure for samples of large sizes. The challenges for our application are to tailor the thickness of the film to the desired solar cell. We are also working to determine whether an aluminum contact layer attached to the pores is a desirable attribute. Anodization of porous alumina has been performed at different temperatures and for different durations. Characterization has been done by FE-SEM, UV-Vis Spectrophotometer and 4-point probe.