Pengukuran Kekasaran Permukaan Lapisan TiO₂ Terhadap Variasi Kecepatan Spin Coating Menggunakan Laser Spekel Fotografi

Mitsaqih, Rima (2026) Pengukuran Kekasaran Permukaan Lapisan TiO₂ Terhadap Variasi Kecepatan Spin Coating Menggunakan Laser Spekel Fotografi. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Lapisan TiO₂ banyak digunakan dalam sel surya, sensor, dan pelapisan optik, di mana kualitasnya sangat dipengaruhi oleh kekasaran permukaan. Penelitian ini bertujuan mengukur dan membandingkan kekasaran permukaan lapisan TiO₂ pada empat variasi kecepatan spin coating menggunakan metode laser spekel fotografi, serta memvalidasi hasilnya menggunakan Atomic Force Microscopy (AFM). Lapisan TiO₂ dideposisikan di atas substrat kaca berukuran 2,5 × 2,5 cm pada kecepatan 500, 1000, 1500, dan 2000 rpm (sampel G1, G2, G3 dan G4), dengan satu keping kaca tanpa lapisan sebagai referensi (G0). Pola spekel direkam menggunakan laser He-Ne (632,8 nm) dan kamera CMOS tanpa lensa (spekel objektif) pada 36 posisi per sampel, kemudian nilai kontras spekel C = σ/⟨I⟩ dihitung secara komputasional. Hasil menunjukkan nilai kontras spekel menurun secara konsisten dari C = 0,3263 (500 rpm) menjadi C = 0,2332 (2000 rpm) atau turun 28,5%, yang mengindikasikan penurunan kekasaran permukaan seiring meningkatnya kecepatan spin coating. Pemetaan spasial 36 posisi mendeteksi anomali ketidakseragaman terlokalisasi pada sampel G3 (1500 rpm) akibat efek penumpukan tepi, sedangkan G4 (2000 rpm) memiliki distribusi paling seragam. Karakterisasi AFM pada G4 menghasilkan Sa = 154,7 nm, Sq = 192,7 nm, Ssk = 0,093, dan St = 1288,0 nm, yang konsisten dengan rentang kekasaran lapisan TiO₂ spin coating pada literatur. Nilai kontras spekel terendah pada G4 bersesuaian dengan nilai Sa terukur terendah, sehingga hasil ini mendukung penggunaan kontras spekel sebagai indikator kekasaran permukaan lapisan TiO₂. Penelitian ini menunjukkan bahwa laser spekel fotografi merupakan metode pengukuran kekasaran permukaan lapisan TiO₂ yang non-kontak, non-destruktif, dan mampu memetakan keseragaman kekasaran secara spasial.
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TiO₂ thin films are widely used in solar cells, sensors, and optical coatings, where their quality strongly depends on surface roughness. This study aims to measure and compare the surface roughness of TiO₂ thin films at four spin coating speeds using laser speckle photography, and to validate the results using Atomic Force Microscopy (AFM). TiO₂ films were deposited on 2.5 × 2.5 cm glass substrates at 500, 1000, 1500, and 2000 rpm (samples G1, G2,G3 and G4), with one uncoated glass substrate as a reference (G0). Speckle patterns were recorded using a He-Ne laser (632.8 nm) and a lensless CMOS camera (objective speckle) at 36 positions per sample, and the speckle contrast C = σ/⟨I⟩ was computed numerically. The results show that the speckle contrast decreased consistently from C = 0.3263 (500 rpm) to C = 0.2332 (2000 rpm), a 28.5% reduction, indicating decreasing surface roughness as the spin coating speed increased. Spatial mapping of the 36 positions detected a localized non-uniformity anomaly in sample G3 (1500 rpm) caused by the edge-bead effect, whereas G4 (2000 rpm) exhibited the most uniform distribution. AFM characterization of G4 yielded Sa = 154.7 nm, Sq = 192.7 nm, Ssk = 0.093, and St = 1288.0 nm, consistent with the roughness range reported in the literature for spin-coated TiO₂ films. The lowest speckle contrast (G4) corresponded to the lowest measured Sa, supporting the use of speckle contrast as an indicator of the surface roughness of TiO₂ thin films. This study shows that laser speckle photography is a non-contact, non-destructive method capable of measuring and spatially mapping the surface roughness of TiO₂ thin films.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	kekasaran permukaan, kontras spekel, laser spekel fotografi, lapisan TiO₂, spin coating laser speckle photography, speckle contrast, spin coating, surface roughness, TiO₂ thin film
Subjects:	Q Science > QC Physics > QC411 Interferometry.
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Physics > 45201-(S1) Undergraduate Thesis
Depositing User:	Rima Mitsaqih
Date Deposited:	28 Jul 2026 07:24
Last Modified:	28 Jul 2026 07:24
URI:	http://repository.its.ac.id/id/eprint/136619

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