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Name (Title):
Dr. Ujjal K. Gautam, ICYS-MANA researcher
Affiliation:
International Center for Young Scientists, International Center for Materials
Nanoarchitectonics (MANA-NIMS)
Address:
1-1 Namiki, Tsukuba. Ibaraki 305-0044, Japan
Email: GAUTAM.Ujjal@nims.go.jp
Home Page: http://www.nims.jp/mana/members/icys_mana_researcher/u_gautam/index.html
Presentation Title:
Solution Synthesis, Cathodoluminescence, and Field-Emission Properties N-Doped ZnO
Nanobullets
Abstract:
In the absence of external influences, homogenous crystallization in solution is expected to
lead to growth that is symmetric at least in two opposite facets. Such was not the case when we
synthesized ZnO nanostructures by employing a solvothermal technique. Instead, the reaction
product was found to consist of tiny bullet-shaped single crystals with abrupt hexagonal bases
and sharp tips. A careful analysis of the product and the intermediate states of the synthesis
reveals that one of the reaction intermediates with sheet-like morphology acts as a self-sacrificing
template and induces such unexpected and novel growth. The synthesis was further extended to
dope the nanobullets with nitrogen as previous studies showed this can induce p-type behavior in
ZnO, which is technologically complementary to the naturally occurring n-type ZnO. Herein, a
soft-chemical approach is used for the first time for this purpose, which is otherwise
accomplished only with high-temperature techniques. Investigations using cathodoluminesce
(CL) spectroscopy reveal stable optical behavior within a pure nanobullet, while the CL spectra
from the surfaces and the cores of the doped samples are different, pointing at a N-rich core.
Finally, even though N-doped ZnO is known to have high conductivity, our study demonstrates
that the field-emission characteristics of ZnO can also be largely enhanced by means of N
doping.
References :
U. K. Gautam, L. S. Panchakarla, B. Dierre, X. Fang, Y. Bando, T. Sekiguchi, A. Govindaraj, D.
Golberg, C. N. R. Rao, Adv. Funct. Mater. (in press)
10.1002/adfm.200801259
114
Poster Session PIR-1