skip to main content

Title: Laser-induced particle size tuning and structural transformations in germanium nanoparticles prepared by stain etching and colloidal synthesis route

In this study, with the aid of Raman measurements, we have observed transformations in small (∼3 nm and ∼10 nm) free-standing Ge nanoparticles under laser light exposure. The nanoparticles were obtained by the chemical stain etching of a monocrystalline Ge wafer and of Ge powder and by colloidal synthesis route. We found that the transformation path depends on laser power and exposure time. At relatively low values of the laser power (2 mW) over a period of 100 min, the Raman signal indicates transformation of the sample from a nanocrystaline to bulk-like state, followed by partial oxidation and finally a conversion of the entire sample into alpha-quartz type GeO{sub 2}. However, when the laser power is set at 60 mW, we observed a heat release during an explosive crystallization of the nanocrystalline material into bulk Ge without noticeable signs of oxidation. Together with the transmission electron microscopy measurements, these results suggest that the chemical stain etching method for the preparation of porous Ge may not be a top-down process as has been widely considered, but a bottom up one. Systematic studies of the laser exposure on Ge nanoparticles prepared by colloidal synthesis results in the fact that the explosive crystallisation is common for H-terminatedmore » and partially disordered Ge nanoparticles regardless of its particle size. We suggest possible bio-medical applications for the observed phenomena.« less
Authors:
 [1] ;  [2] ; ; ; ;  [1] ;  [3]
  1. Centre for Condensed Matter and Materials Physics, School of Physics and Astronomy, Queen Mary, University of London, London E1 4NS (United Kingdom)
  2. (Turkey)
  3. Bio-Nanotechnology Research and Development Centre, Fatih University, 34500 Buyukcekmece, Istanbul (Turkey)
Publication Date:
OSTI Identifier:
22493097
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CRYSTALLIZATION; CRYSTALS; ETCHING; GERMANIUM; GERMANIUM OXIDES; HEAT; LASER RADIATION; NANOPARTICLES; NANOSTRUCTURES; PARTICLE SIZE; POROUS MATERIALS; POWDERS; QUARTZ; RAMAN EFFECT; STAINS; TRANSMISSION ELECTRON MICROSCOPY