AVS 51st International Symposium
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP24
Synthesis and Characterization of Germanium Nanocrystals

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: H. Gerung, University of New Mexico
Authors: H. Gerung, University of New Mexico
S.D. Bunge, Sandia National Laboratories
T.J. Boyle, Sandia National Laboratories
C.J. Brinker, University of New Mexico
J. Lee, University of New Mexico
M. Osinski, University of New Mexico
S.M. Han, University of New Mexico
Correspondent: Click to Email
Semiconductor nanocrystals promise numerous potential applications, ranging from phosphors to biosensors. Herein, we focus on synthesis and characterization of Ge nanocrystals (NCs). Compared to group III-V or II-VI compound semiconductor NCs, the synthesis of Ge NCs in solution has been a challenge due to their covalent bond nature. Very few solution-phase syntheses have been reported, and the precursor preparation often involves a relatively high-pressure (>1 atm) process. We have developed a new method of synthesizing Ge NCs. The size of these crystals ranges from 3 to 10 nm. The control over shape and size dispersion of Ge NCs will be discussed in this presentation. We will present the effect of processing temperature and precursor concentration on the size. The synthesis relies on solution reduction of Ge@super 2+@ to Ge@super 0@ with commercially available precursors at relatively low temperature (300 °C) and at 1 atm of Ar ambient. This new synthetic route is scalable for mass production of Ge NCs. Photoluminescence spectra of Ge NCs show emission from 380 to 510 nm, and they demonstrate the quantum confinement effect of Ge NCs. However, ultraviolet-visible (UV-Vis) spectroscopy and attenuated-total-reflection Fourier transform infrared spectroscopy (ATR-FTIRS) show that Ge NCs are sensitive to air exposure, and they degrade over time in the absence of proper surface passivation. We therefore utilize different types of surfactants to encapsulate and stabilize the Ge NCs. The stabilized Ge NCs can be then incorporated into a silica matrix via sol-gel approach to form a self-assembled 3-dimensionally (3-D) ordered matrix.