Silicon Quantum Wires Oxidation and Transport Studies

Abstract

Fabricating well controlled nanostructures and obtaining precise structural, electrical, and optical information from them are essential for understanding die intrinsic properties of silicon (Si) nanostructures, which in turn is important for exploring the potential of quantum confinement induced light emission from crystalline Si. A combination of high resolution electron beam lithography, anisotropic reactive ion etching (RIE), and thermal oxidation has been successfully applied to obtain sub-5 nm Si columnar structures [1]. A transmission electron microscopy (TEM) technique has also been used to characterize die precise structural dimensions of these columns [1]. To obtain the electrical and optical information, a process based on polyimide planarization was developed to establish electrical contacts to these nanostructures. The same process is also applicable for fabricating device structures to study electrically pumped optical response. Preliminary transport studies have confirmed current conduction through die Si nano-pillars and yielded an estimate of die conductivity.

Structural imaging of a Si quantum dot: Towards combined PL and TEM characterization

“…Oxidation occurs at relatively low temperature in order to utilize the selflimiting regime [7] whereby stress build up at high curvatures more or less inhibits further oxidation. For a narrow, vertical pillar this will result in slower oxidation at the top where the curvature is largest compared to the rest of the pillar.…”

“…First, due to the non-uniform oxidation at surface with curvatures, the silicon trunk is consumed in two places (Fig. 2a), corresponding to the positions of the outer surface with concave shape [7]. At this stage a nanocrystal is formed at the top of a pillar where oxidation is slowed due to the convex curvature.…”