Continuous Flow Supercritical Chemical Fluid Deposition of Optoelectronic Quality CdS

Abstract

Supercritical chemical fluid deposition (SCFD) has attracted considerable attention recently due to its ability to fill high aspect ratio templates. One technologically relevant example is the damascene process deposition of conformal low-resistivity copper interconnects within the latest generation 32nm node integrated circuits. Furthermore, SCFD technology can be extended to a wide range of metals, including Cu, Ni,[6] Au, Ru, Co, Rh, and Ir into macro- and meso-structured environments for a variety of applications, particularly micro-electronics. More recently SCFD has been demonstrated as uniquely suitable for the deposition of metals, polymers, and elemental semiconductors into micro-structured optical fibers enabling a new generation of photonic devices including chemical sensors and optical modulators. The ability to deposit a conformal coating of metals, oxides, and indirect bandgap, elemental semiconductor materials via SCFD inside meso- and micro-scale template structures has been clearly demonstrated, with the depositions yielding continuous tubes, or wires without detectable central voids, ca. 3 nm diam. It is clear that the extension of SCFD to the deposition of optoelectronic quality direct bandgap semiconductors would be a valuable technological advance, with important niche applications.