Formation of ultrahigh density Ge nanodots on oxidized Ge/Si(111)

Apr 27, 2004

Yoshiaki Nakamura et al. present their work in Journal of Applied Physics (Vol. 95, No. 9, pp. 5014–5018 ). They grew Ge nanodots with a typical size of ~4 nm and ultrahigh density (>1012 cm–2) on ultrathin SixGe1–x oxide films made by oxidizing Ge wetting layers grown on Si (111)–(7×7) surfaces. This is a promising result for the application of SiGe-based optoelectronics because of the ultrahigh density of Ge dots in addition to their small dot size.

Considerable efforts have been made to fabricate quantum dots with a size on the order of 10 nm because of the potential to modify the physical properties of the material through the effects of quantum carrier confinement. To use the quantum confinement phenomena, the dots in nanostructures have to be smaller than 10 nm for SiGe-based electronics. However, three-dimensional (3D) Ge islands fabricated by a self-organization process of strained Ge layers on Si substrates are larger than 30 nm because the surface morphology is formed through unstable intermediate phases. In addition to dot miniaturization, another requirement is that the dots be formed with a high density.

Yoshiaki Nakamura et al. achieved 4 nm dots with ultrahigh density by replacing SiO2 films with oxidized SixGe1–x films. The density of the nanodots was independent of the Ge deposition rate, indicating that the chemical reaction between Ge atoms and the oxide films determined the nucleation of Ge nanodots. The size and density of Ge nanodots grown on the ultrathin SixGe1–x oxide films depended on the growth temperature and deposition amount. These dependences indicate that they can form the Ge nanodots with ultrahigh density controllably by using ultrathin SixGe1–x oxide films.

Explore further: Scientists fabricate defect-free graphene, set record reversible capacity for Co3O4 anode in Li-ion batteries

add to favorites email to friend print save as pdf

Related Stories

Amazing raw Cassini images from this week

33 minutes ago

When Saturn is at its closest to Earth, it's three-quarters of a billion miles away—or more than a billion kilometers! That makes these raw images from the ringed planet all the more remarkable.

Researchers look at small RNA pathways in maize tassels

43 minutes ago

Researchers at the University of Delaware and other institutions across the country have been awarded a four-year, $6.5 million National Science Foundation grant to analyze developmental events in maize anthers ...

Proteins: New class of materials discovered

43 minutes ago

Scientists at the Helmholtz Center Berlin along with researchers at China's Fudan University have characterized a new class of materials called protein crystalline frameworks.

Recommended for you

Copper shines as flexible conductor

2 hours ago

Bend them, stretch them, twist them, fold them: modern materials that are light, flexible and highly conductive have extraordinary technological potential, whether as artificial skin or electronic paper.

Nanoparticles may aid oil recovery, frack fluid tracking

3 hours ago

Two Colorado State University researchers are examining how nanoparticles move underground, knowledge that could eventually help improve recovery in oil fields and discover where hydraulic fracking chemicals ...

User comments : 0