Sains Malaysiana 43(2)(2014):
273–281
Synthesis
and Characterization of Cu-doped ZnO Nanorods
(Sintesis dan Pencirian Cu-terdop Nanorod ZnO)
S.Y. PUNG*1, C.S. ONG1, K. MOHD ISHA2& M.H.
OTHMAN2
1School of Materials and Mineral Resources Engineering, Engineering
Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal,
Pulau Pinang, Malaysia
2Advanced Materials Research Centre, SIRIM Berhad, Lot 34, Jalan
Hi-Tech 2/3,
Kulim Hi-Tech Park, 09000 Kulim, Kedah, Malaysia
Diserahkan: 7 Januari 2013/Diterima: 17 Julai 2013
ABSTRACT
Cu-doped ZnO nanorods were synthesized by sol-gel method using
zinc nitrate tetrahydrate, methenamine and cupric acetate monohydrate as
precursors. The as-synthesized ZnO nanorods have a twin-rod structure. The
polar (002) surface of ZnO nanorods, which could be either negatively charge
(O-terminated) or positively charged (Zn-terminated), was responsible for the
formation of twin-rod structure. The results showed that the size, aspect
ratio, crystallinity and c-lattice parameter of Cu doped ZnO nanorods decreased
with increasing of Cu dopant concentration. In fact, the presence of Cu
retarded the growth of ZnO nanorods in its preferred growth direction, i.e.
(0001). The XPS analysis indicates that Cu ions were oxidized (Cu2+) and substituted
into the ZnO lattice at the Zn2+ site. The presence of Cu reduced the optical
bandgap of ZnO from 3.34 eV (undoped ZnO nanorods) to 3.31 eV (20 mol% Cu doped
ZnO). Besides, it induced a visible PL emission at 2.97 eV, which could be related
to the transition of electrons from conduction band (Ec) to Cu acceptor energy
level (Ev +
0.45 eV) radiatively.
Keywords: Copper; in-situ doping; semiconductor; sol-gel processes; ZnO nanorods
ABSTRAK
Cu-terdop nanorod ZnO telah disintesis dengan kaedah sol-gel
dengan menggunakan zink nitrat tetrahidrat, metenamin dan kuprik asetat
monohidrat sebagai prapenanda. Nanorod ZnO yang disintesis ini mempunyai
struktur rod berkembar. Permukaan (002) nanorod ZnO yang berkutub, sama ada caj
negatif (dipangkalkan oleh O) atau caj positif (dipangkalkan oleh Zn),
bertanggungjawab untuk pembentukan struktur rod berkembar ini. Keputusan
menunjukkan bahawa saiz, nisbah bidang, kehabluran dan parameter kekisi-c
Cu-dop nanorod ZnO ini menurun dengan meningkatnya pendopan kepekatan Cu.
Sebenarnya, kehadiran Cu menghalang pertumbuhan nanorod ZnO dalam halaan
pertumbuhan yang diutamakan, iaitu (0001). Analisis XPS menunjukkan bahawa
ion Cu telah dioksidakan (Cu2+) dan digantikan dalam kekisi ZnO di
kedudukan Zn2+. Kehadiran Cu juga mengurangkan jalur
tenaga optikal ZnO daripada 3.34 eV (nanorod ZnO tanpa dop) ke 3.31 eV (20 mol%
ZnO Cu-terdop). Tambahan lagi, ia menghasilkan pancaran PL di 2.97 eV, yang boleh
dikaitkan dengan peralihan elektron dari jalur konduksi (Ec) kepada paras tenaga Cu
penerima (Ev + 0.45 eV) secara radiatif.
Kata kunci: Kuprum; nanorod ZnO; pendopan in-situ; proses sol-gel; semikonduktor
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*Pengarang
untuk surat-menyurat; email: sypung@eng.usm.my
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