Self-assembled nanorings in Si-capped Ge quantum dots on (001)Si

Abstract

Nanorings with an average height and diameter of 1.2 and 65 nm, respectively, were observed to form in Si-capped Ge quantum dots grown at 600 °C by ultrahigh-vacuum chemical vapor deposition. The nanorings were captured with the rapid cooling of the samples with appropriate amount of Si capping. Based on the results of transmission electron microscopy and Raman spectroscopy, the formation of nanorings is attributed to alloying and strain relief in the Si/Ge/ ͑001͒Si system. The self-assembly of nanorings provides a useful scheme to form ultrasmall ring-like structure and facilitates the characterization of the physical properties of unconventional quantum structures.

Field-emission properties of self-assembled Si-capped Ge quantum dots

“…The previous results demonstrate that the formation of nanorings is closely correlated with a strain-driven process. The detailed formation mechanism and control of these nanorings were reported elsewhere [9]. For further deposition with 56 eq-MLs Si-capping layer, the nanorings tended to smooth out and were no longer evident in the AFM images.…”

“…In the previous investigation of the evolution of the Ge QDs during the initial stages of Si encapsulation up to 28 equivalent monolayers (eqMLs, 1 eq-ML= 6.27 Â 10 14 atom/cm 2 ) [8], drastic changes of shape and surface morphology of the Ge QDs have been observed [9]. In this work, the field-emission characteristics of self-assembled Ge QDs on Si(001) at different Si coverage are investigated.…”

Compositional mapping of semiconductor quantum dots and rings

“…The shape and composition evolution from SiGe QD to QR was monitored as a function of Si deposition on Ge/Si(001) islands [95]. As previously found by Rastelli et al [96], the initial prevalently dome-shaped islands tend to transform into pyramids upon capping with 14 ML Si, due to the different equilibrium shape of QDs depending on volume and composition as a result of intermixing.…”

Pyramid‐Shaped Si/Ge Superlattice Quantum Dots with Enhanced Photoluminescence Properties

“…[7] In addition to Ge QDs, various nanostructures, such as silicide nanodots and SiGe nanorings, have also been grown on SiGe. [8,9] In the present study, taking advantage of the relatively low etching rate and uniform size of Ge QDs on a Si/Ge SL, a method has been developed to fabricate pyramid-shaped Si/Ge SL nanodots with excellent uniformity over large areas. The fabrication process is compatible with Si/ SiGe-based integrated circuit technology.…”