Sains Malaysiana 42(11)(2013): 1663–1670

Struktur dan Sifat Optik Filem Nipis Nanozarah ZnO Terdop Ga

(Structural and Optical Properties of Ga-doped ZnO Nanoparticle Thin Films)

R. AWANG*, SITI N.H.M. DAUD, CHI CHIN YAP, MOHAMMAD HAFIZUDDIN HAJI JUMALI & Z. ZALITA

Pusat Pengajian Fizik Gunaan, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E. Malaysia

Received: 13 June 2012/Accepted: 11 June 2013

ABSTRAK

Filem nipis ZnO terdop Ga (ZnO:Ga) disediakan menggunakan teknik sol-gel dan salutan berputar. Ga didopkan kepada ZnO dengan peratusan berat (wt. %) yang berbeza iaitu 0, 2, 4, 6 dan 8 wt. %. Kesan pengedopan Ga ke atas struktur dan sifat optik filem nipis ZnO dikaji. Pencirian struktur filem nipis ini dilakukan menggunakan kaedah pembelauan sinar-X (XRD), mikroskop imbasan elektron pancaran medan (FESEM) dan mikroskop daya atom (AFM). Pencirian sifat optik filem nipis pula dilakukan menggunakan spektroskopi ultraungu cahaya nampak (UV-VIS) dan fotoluminesen (PL). Ujian XRD mengesahkan kesemua sampel berstruktur wurtzit. Saiz kristalit ZnO mengecil dengan peningkatan peratusan berat Ga seterusnya mengurangkan kekasaran permukaan filem. Pengedopan Ga menunjukkan peratus transmisi cahaya pada panjang gelombang 300 - 380 nm bertambah berbanding filem nipis ZnO tanpa dop. Nilai jurang tenaga optik, Eg dan keamatan PL filem nipis ZnO meningkat apabila pengedopan Ga dilakukan. Hasil kajian ini menunjukkan saiz kristalit yang lebih kecil memberi kesan ke atas sifat optik sampel pada peratus pengedopan Ga 0-6%. Pada peratus pengedopan Ga yang lebih tinggi, kesan transformasi struktur menjadi lebih dominan dalam mempengaruhi nilai Eg.

Kata kunci: Fotoluminesen; jurang tenaga optik; sol-gel

ABSTRACT

Ga-doped zinc oxide (ZnO:Ga) thin films were prepared by using sol-gel spin coating method. Different weight percentage, wt. % (0, 2, 4, 6 and 8 wt. %) were doped into ZnO thin films. The effects of Ga dopant on structural and optical properties of these films were investigated. The structural properties of these thin films were studied by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The optical properties were examined by ultraviolet visible spectroscopy (UV-VIS) and photoluminescence (PL) spectroscopy. XRD measurement indicates that all the samples displayed wurtzite structure. The crystallite size of the films reduced with the increase of Ga concentrations and the surface roughness remarkably decreased. Ga-doping has clearly increased the light transmission percentage for wavelength in the range of 300 - 380 nm as compared to un-doped ZnO film. The optical band gap, Eg and the PL intensity of the films increased with the Ga-doping. The experimental results showed that, smaller crystallite size has an effect on the optical properties of the samples at 0-6% of Ga-doping. Structural transformation has more dominant influence to the Eg value at higher percentage of Ga-doping.

Keywords: Optical band gap; photoluminescence; sol-gel

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*Corresponding author; email: rozida@ukm.my