Laser Ablation Fabricated Nano-Composite of Metal Silicide Crystallines in Silicon Wire
- PDF / 99,919 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 48 Downloads / 161 Views
Laser Ablation Fabricated Nano-Composite of Metal Silicide Crystallines in Silicon Wire Jifa Qi1,∗ and Yasuaki Masumoto1,2 1 Single Quantum Dot Project, ERATO, Japan Science and Technology Corporation, Tsukuba, Ibaraki 300-2635, Japan 2 Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan ABSTRACT Silicon nanowires containing a high density of copper atoms were prepared by laser ablation of Si/metal mixture targets at 1200 °C in argon gas flow. Copper atoms can gather in Si nanowires and precipitate into copper silicide nanocrystals distributed alone the wire axis. The diameters of the copper silicide nanocrystals increase with that of the host nanowire. The possible growth process of the composite nanowires was proposed. INTRODUCTION Nanometer-sized composite, consisting of several different types of nanostructures, is of extreme interests due to the unique properties arising from both the quantum size effect of each component and the interface effect, and the possible applications. To date, several semiconductor nanocomposites have been investigated [1-3]. However, so far, the nanosized composite structures of the metal or metal silicide nanocrystals embedded in nanosized silicon structures have not yet been reported to our knowledge. Recently, a method combining laser ablation cluster formation and VLS growth process was developed for synthesis of bulk quantities of silicon nanowires [3-5]. Like the bulk silicon, the metal diffusion, solubility and gathering in the silicon nanowires is an important subject. In the present paper, we report the formation of silicon nanowires containing high density of copper atoms, and the copper atom precipitated silicon nanowires–a nano-composite of the copper silicide nanocrystal array in the silicon nanowire. EXPERIMENTAL DETAILS A quartz tube was mounted inside of a high-temperature tube furnace of 50 cm in length.
∗
Present address: National Institute of Materials and Chemistry Research (NIMC), Tsukuba 305-8565, Japan.
[email protected].
F12.5.1
Mat. Res. Soc. Symp. Proc. Vol. 638 © 2001 Materials Research Society
Figure 1.
(a) Typical SEM image of the silicon nanowires.
(b) HRTEM image of a silicon
nanowire.
The spacing between (111) planes of Si nanowire is about 0.31 nm.
Silicon powder (99.999%) was mixed with Fe (99.9%) and Cu (99.99%) powder with a typical molar ratio of 0.85:0.05:0.10. The mixture powder was ball-milled and pressed into a plate. The plate was placed in the center of the quartz tube, which was evacuated by a mechanical rotary pump. High-purity argon was passed through the quartz tube at a flow rate of 50 standard cubic centimeters per second when furnace reached 400°C. The total tube pressure was controlled at a range between 50 and 100 Pa. As well as the furnace reached 1200°C, the temperature and the Ar flow was kept constant during the three-hour growth process. A pulsed XeCl excimer laser (308 nm, pulse energy and repetition are 170 mJ and 10 Hz, respectively)
Data Loading...
