Delivered by Publishing Technology to: Tohoku University IP: 130.34.74.60 On: Tue, 10 Mar 2015 08:38:49 Copyright: American Scientific Publishers Copyright © 2009 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Nanoscience and Nanotechnology Vol. 9, 5865–5869, 2009 Formation and Characterization of Sub-Nanometer Scale cF8 Ge Precipitates in Si-Based Amorphous Matrix Dmitri V. Louzguine-Luzgin 1 2 ∗ , Parmanand Sharma 2 , Mikio Fukuhara 2 , Andriy Dmytruk 3 , and Akihisa Inoue 1 2 1 WPI Advanced Institute for Materials Research, Tohoku University, Aoba-Ku, Sendai, 980-8577, Japan 2 Institute for Materials Research, Tohoku University, Aoba-Ku, Sendai, 980-8577, Japan 3 Center for Interdisciplinary Research, Tohoku University, Aramaki Aza Aoba, Aoba-ku, Sendai, 980-8578, Japan Sub-nanometer size cF8 Ge clusters are found to be homogeneously distributed within the Si–Mn amorphous matrix of the SiGeMn thin films deposited by sputtering technique on silicon substrate. The existence of such clusters is observed by XRD and TEM. The electrical conduction in such a composite film seems to be governed by the variable range hopping. Such a two-phase semi- conductive composite material with nearly atomic-scale phase separation may be considered as a suitable functional material for nano-electronics and nano-electromechanical systems. Keywords: Amorphous Alloys, Semiconductors, Nanomaterial. 1. INTRODUCTION Amorphous metalloids Si, Ge and their alloys are impor- tant semiconductive materials. 1 The structure and proper- ties of amorphous Si and Ge have been investigated long ago. 2–4 Some Al-based alloys 5 are known to form metal- lic glassy alloys. 67 Two decades ago Al–Si–TM (TM- transition metal) and Al–Ge–TM alloys with high Ge content up to 50 at% were produced 8 9 by rapid solidifi- cation of the melt 10 using a melt spinning technique. The detailed structural study of the atomic structure among the Ge-based alloys has been done for the Ge 50 Al 40 Cr 10 alloy by using conventional X-ray diffraction, anomalous X-ray scattering and transmission electron microscopy. 11 Following recent progress in metallic glassy alloys 1213 Si–Al–TMs (TMs-several transition metals) alloys contain- ing up to 60 at% Si were produced later. 14 The amor- phous alloys containing up to 70 at% Ge were also obtained by rapid solidification of the melt. 15 The addition of RE metals favors the glass-formation. 16 Glass-forming ability (GFA) of some Ge-based alloys is relatively high among amorphous alloys (marginal glass-formers). For example, critical ribbon thickness for amorphous Ge 55 Al 30 Cr 10 Ce 5 ribbon samples produced by rapid solid- ification of the melt was about 0.125 mm. It is known ∗ Author to whom correspondence should be addressed. that in order to enhance the glass-forming ability of an alloy three empirical principles should be satisfied: multicomponent systems consisting of at least three ele- ments; significant atomic size ratios among the main con- stituent elements; and negative heats of mixing among the three main constituent elements. 17 RE metals sig- nificantly raise the degree of satisfaction to these prin- ciples, i.e., they have large negative values of heat of mixing for binary liquid alloys with Ge and are signifi- cantly larger in size than Ge. A comparative study of the GFA of Si–Ni–Nd and Ge–Ni–Nd alloys have been per- formed and indicated that an addition of Nd to Ge–Ni alloys caused formation of an amorphous single phase in the Ge 60 Ni 35 Nd 5 18 alloy but not in Si–Ni–Nd alloys. Taking into consideration geometrical, physical and chem- ical factors, Si–Ni–Nd alloys show better adherence to the requirements while the amorphous single phase was obtained only in the Ge–Ni–Nd system alloy. Nanotechnology is an emerging frontier for the devel- opment of various future electronic devices. The minia- turization of electrical components greatly increased the utility and portability of electronic devices. The semicon- ductor industry has produced one of the most sophisti- cated manufacturing processes. The key challenge have been the scaling of the transistors. Indeed, the production and wide use of common devices such as personal com- puters is dependent on advances in nanotechnology. Up J. Nanosci. Nanotechnol. 2009, Vol. 9, No. 10 1533-4880/2009/9/5865/005 doi:10.1166/jnn.2009.1221 5865