Investigating the Composition and Conductance Distributions on Highly GeSi Mixed Quantum Dots and Inside Oxidation Problem

Abstract

With the help of a nanoscale trench, the composition and conductance distributions of single GeSi quantum dots (QDs) are obtained by conductive atomic force microscopy combined with selective chemical etching. However, the obtained composition and current distributions are unwonted and inconsistent on the QDs grown at 680°C. With a series of confirmatory experiments, it is suggested that a thick oxide layer is formed and remains on the QDs' surface after etching. Though this selective chemical etching has already been widely applied to investigate the composition distribution of GeSi nanostructures, the oxidation problem has not been concerned yet. Our results indicate that the oxidation problem could not be ignored on highly GeSi mixed QDs. After removing the oxide layer, the composition and conductance distributions as well as their correlation are obtained. The results suggest that QDs' current distribution is mainly determined by the topographic shape, while the absolute current values are influenced by the Ge/Si contents.

Controlled Formation of Stacked Si Quantum Dots in Vertical SiGe Nanowires

“…SiGe QD formation has been accomplished on Si(100) surfaces through a variety of patterning and deposition methods − as well as through the use of SiGe/Si heterostructures . Ge QDs have also been realized through growth on Si(100) surfaces, − as well as through controlled oxidation of SiGe nanostructures. ,, In particular, vertically stacked Ge QDs have been fabricated through SiGe pillar oxidation, with the Ge QD position being controlled via Ge QDs “burrowing” through SiO 2 to reach SiN layers. − Vertically stacked Si QDs encapsulated in SiO 2 have also been fabricated through oxidation of corrugated Si nanopillars, resulting in stacked Si QDs with visible to near-infrared photoluminescence. However, SiO 2 is limited as an encapsulating material for some QD microelectronics applications in part due to the insulating nature of oxide.…”