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Abstrak :
ABSTRAK
ABSTRACT
ZnO is one of the potential semiconductors for photodetector application. However, the responsivity and the time responses are still low and need more improvement. Therefore, the nanohybrid between ZnO and the transition metal decalchogenides (TMDs) is a promosing structure could increase the photodetector performance. In this study, ZnO nanorods structure was fabricated on the interdigitated indium tin oxide (ITO) electrode on glass substrate via ultrasonics spray pyrolysis and hydrothermal method, then MoS2 nanosheets with two different liquid exfoliation times (4 and 8 hours) were deposited on ZnO nanorods by spin-coating method. In this study it has been shown that the variation of exfoliation time of 4 and 8 hours produces MoS2 nanosheets that are almost the same number of layers, namely 3-6 layers. However, MoS2 8H can be deposited much more onto the surface of ZnO nanorods. Generally, this study shows that the addition of MoS2 can improve the performance of the ZnO nanorods photodetector in both the UV region and the visible light. Based on the increase in the value of Responsivity, Detectivity and Sensitivity, the addition of MoS2 8H produces the best nanohybrid MoS2/ZnO structure especially for red light photodetectors (625 nm) due to the highest increase in photocurrent and high electron mobility in MoS28H.

Abstrak :

ZnO merupakan salah satu material semikonduktor yang unggul untuk aplikasi fotodetektor Ultraviolet (UV) karena memiliki celah pita yang lebar, sifat transparasi yang baik, tidak beracun, dan biaya produksi rendah dengan proses sintesis yang sederhana. Namun, mobilitas elektron fotodetektor UV masih rendah sehingga photocurrent dan responsivitas yang dihasilkan belum optimal. Oleh karena itu dalam penelitian ini dibuat heterostructure ZnO nanorods dengan MoSe₂ nanosheets. MoSe₂ nanosheets disintesis dengan metode liquid phase exfoliation dan dideposisi di atas permukaan ZnO nanorods yang ditumbuhkan di atas substrat kaca berelektroda Indium Tin Oxide (ITO) dengan metode spin coating. Penelitian ini menghasilkan MoSe₂ nanosheets dan ZnO/MoSe₂ dengan celah pita masing-masing sebesar 1,92 dan 3,17 eV. Penambahan MoSe₂ nanosheets pada permukaan ZnO nanorods dapat meningkatkan responsivitas, detektivitas, dan sensitivitas fotodetektor UV berbasis ZnO nanorods, yaitu masing-masing sebesar 1,25 A/W, 1,9 Jones, dan 5701%. Peningkatan kinerja ini mungkin akibat pengurangan rekombinasi elektron-hole hasil fotoeksitasi oleh sinar UV dan penurunan arus gelap mungkin karena elektron terperangkap oleh MoSe₂. Sedangkan, fotodetektor ZnO nanorods dan ZnO/MoSe₂ tidak berfungsi di bawah penyinaran cyan dan red, karena photocurrent yang dihasilkan sangat kecil.

 

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ZnO is one of the semiconductor materials that has been received much attention and also considered as a promising candidate for the photodetector due to its wide bandgap, good transparencey, non-toxicity, low-cost and simple preparation. However, photocurrent and responsivity of ZnO-based photodetector based on nanorods is less optimal because of its low electron mobility. Therefore, this study propose the heterostructure of ZnO nanorods and MoSe₂ nanosheets. MoSe₂ nanosheets were synthesized by the liquid phase exfoliation method and deposited on the surface of ZnO nanorods grown on Indium Tin Oxide electrode coated glass substrate (ITO) via the spin coating method. MoSe₂ nanosheets and ZnO/MoSe₂ show a bandgap of 1,92 and 3,2 eV, respectively. Responsivity, detectivity, and sensitivity of ZnO/MoSe₂ heterostructures is is 1,25 A/W; 1,9 Jones; and 5701%, respectively. The increase in performance may be due to a reduction in the recombination of UV photoexcitated electron-holes and a decrease in dark currents possibly due to electrons being trapped by MoSe₂. Whereas, ZnO nanorods and ZnO/MoSe₂ photodetectors do not function under cyan and red irradiation, because the generated photocurrent is very small.

 

Abstrak :
Penambahan material Transition Metal Dichalcogedines (TMD) pada fotodetektor berbasis ZnO telah menarik banyak perhatian karena dapat meningkatkan kinerja fotodetektor. Material TMD yang digunakan pada pekerjaan ini adalah Tungsten disulfide (WS₂). WS₂ menunjukan sifat optik dan listrik yang lebih baik saat bentuknya berubah dari bulk menjadi monolayer. Pada pekerjaan ini, kami melaporkan pengaruh penambahan WS₂ nanosheet pada fotodetektor berbasis ZnO nanorods. ZnO disiapkan menggunakan metode hidrotermal selama 6 jam dan WS₂ disiapkan dengan metode liquid phase exfoliation selama 8 jam. Larutan WS₂ yang telah dieksfoliasi kemudian dideposisi di atas permukaan ZnO nanorods menggunakan metode spin coat. Sampel dikarakterisasi menggunakan SEM, TEM, EDS, Raman spektroskopi, UV-Vis spectrometer dan Uji fotodetektor dengan penyinaran cahaya 365, 505, dan 625 nm. Keberhasilan yang didapatkan dari penelitian ini adalah berupa penurunan nilai dark current yang terjadi akibat penambahan lapisan WS₂ di atas permukaan ZnO nanorods. Penurunan nilai dark current ini berdampak pada peningkatan ketiga parameter kinerja fotodetektor yaitu Sensitivitas, Responsivitas, dan Detektivitas yang dihitung pada tegangan 5V. Dibawah penyinaran sinar UV (365 nm) dengan daya 3.0 mW, nilai sensitivitas meningkat dari 129.06% menjadi 334.04%, nilai responsivitas meningkat dari 0.93 A/W menjadi 1.11 A/W, dan kemampuan detektivitas naik dari 2.5x10⁹ menjadi 4.4 x 10⁹ Jones.

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The addition of Transition Metal Dichalcogedines (TMD) towards the photodetector based on ZnO has attracted much attention due to their ability to improve the performance of photodetector. TMD that used in this work is Tungsten disulfide (WS₂). WS₂ shows better optical and electrical properties when it changed from bulk to monolayer. In this work, we report the effect of  WS₂ nanosheets addition to the performance of photodetector based on ZnO nanorods. ZnO were prepared by hydrothermal method for 6 hours and WS₂ were prepared by liquid phase exfoliation for 8 hours. Exfoliated WS₂ was deposited on the ZnO nanorods surface by spin-coating method. The sample was characterized by SEM, EDS, TEM, Raman spectroscopy, UV-Vis spectrometer, and photodetector test using 365, 505, and 625 nm incident lights. Our work has successfully lowered the dark current after WS₂ addition on ZnO nanorods surface. It has an impact to the enhancement of photodetector performances such as sensitivity, responsivity, and detectivity that measured at voltage bias 5V. Under the illumination of UV light with 3.0 mW power, the sensitivity increased from 129.06% to 334.04%, responsivity increased from 0.93 to 1.11 A/W, and the detectivity increased from 2.5 x 10⁹  to 4.4 x 10⁹ Jones.