scholarly journals Preparation of hexagonal nanoporous Al2O3/TiO2/TiN as a novel photodetector with high efficiency

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Asmaa M. Elsayed ◽  
Mohamed Rabia ◽  
Mohamed Shaban ◽  
Arafa H. Aly ◽  
Ashour M. Ahmed

AbstractThe unique optical properties of metal nitrides enhance many photoelectrical applications. In this work, a novel photodetector based on TiO2/TiN nanotubes was deposited on a porous aluminum oxide template (PAOT) for light power intensity and wavelength detection. The PAOT was fabricated by the Ni-imprinting technique through a two-step anodization method. The TiO2/TiN layers were deposited by using atomic layer deposition and magnetron sputtering, respectively. The PAOT and PAOT/TiO2/TiN were characterized by several techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray (EDX). The PAOT has high-ordered hexagonal nanopores with dimensions ~ 320 nm pore diameter and ~ 61 nm interpore distance. The bandgap of PAOT/TiO2 decreased from 3.1 to 2.2 eV with enhancing absorption of visible light after deposition of TiN on the PAOT/TiO2. The PAOT/TiO2/TiN as photodetector has a responsivity (R) and detectivity (D) of 450 mAW-1 and 8.0 × 1012 Jones, respectively. Moreover, the external quantum efficiency (EQE) was 9.64% at 62.5 mW.cm−2 and 400 nm. Hence, the fabricated photodetector (PD) has a very high photoelectrical response due to hot electrons from the TiN layer, which makes it very hopeful as a broadband photodetector.

2016 ◽  
Vol 316 ◽  
pp. 160-169 ◽  
Author(s):  
Nicholas David Schuppert ◽  
Santanu Mukherjee ◽  
Alex M. Bates ◽  
Eun-Jin Son ◽  
Moon Jong Choi ◽  
...  

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Anna Majtyka ◽  
Anna Nowak ◽  
Benoît Marchand ◽  
Dariusz Chrobak ◽  
Mikko Ritala ◽  
...  

The present paper pertains to mechanical properties and structure of nanocrystalline multiferroic BeFiO3(BFO) thin films, grown by atomic layer deposition (ALD) on the Si/SiO2/Pt substrate. The usage of sharp-tip-nanoindentation and multiple techniques of structure examination, namely, grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectrometry, enabled us to detect changes in elastic properties(95 GPa≤E≤118 GPa)and hardness(4.50 GPa≤H≤7.96 GPa)of BFO after stages of annealing and observe their relation to the material’s structural evolution. Our experiments point towards an increase in structural homogeneity of the samples annealed for a longer time. To our best knowledge, the present report constitutes the first disclosure of nanoindentation mechanical characteristics of ALD-fabricated BeFiO3, providing a new insight into the phenomena that accompany structure formation and development of nanocrystalline multiferroics. We believe that our systematic characterization of the BFO layers carried out at consecutive stages of their deposition provides pertinent information which is needed to control and optimize its ALD fabrication.


2007 ◽  
Vol 990 ◽  
Author(s):  
Sung-Hoon Chung ◽  
Vladislav Vasilyev ◽  
Evgeni Gorokhov ◽  
Yong-Won Song ◽  
Hyuk-Kyoo Jang

ABSTRACTWe investigated effects of thermal annealing on Ru films deposited on the 8 inch Si substrates using a volatile liquid-phase Ru precursor, tricarbonyl-1,3-cyclohexadienyl ruthenium (Ru(CO)3(C6H8)) by an atomic layer deposition (ALD) technique. Structural and electrical properties of the films were characterized by scanning probe microscopy, X-ray diffractometry, sheet resistance. Grazing incidence X-ray diffraction (GIXRD) patterns show typical Ru hexagonal polycrystalline peaks as annealing temperature was increased. At the highest annealing temperature condition, Ta = 700 °C electrical resistivity become 6 times less than in as-deposited films.


2007 ◽  
Vol 22 (12) ◽  
pp. 3455-3464 ◽  
Author(s):  
Rajesh Katamreddy ◽  
Ronald Inman ◽  
Gregory Jursich ◽  
Axel Soulet ◽  
Christos Takoudis

Tetrakis-diethylamino hafnium (TDEAH), tris-diethylamino aluminum (TDEAA), and ozone were used for the atomic layer deposition (ALD) of HfO2, Al2O3, and HfAlOx films. The ALD rates were measured to be 1.1 Å/cycle for HfO2 and 1.3 Å/cycle for Al2O3. The ALD temperature windows were found to be between 200 and 325 °C for TDEAA, and between 200 and 275 °C for TDEAH. The overlap of these ALD windows between 200 and 275 °C is critical for ALD of the composite film, HfAlOx. In addition to the overlapping ALD temperature windows, the two metal precursors have similar thermal characteristics, as shown by TGA and differential scanning calorimetry. As-deposited films and films postannealed at 600 and 800 °C films were analyzed using Fourier transformed infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffraction (XRD) techniques. FTIR spectra revealed interfacial oxide growth during deposition of both HfO2 and Al2O3 whose thickness increased with annealing temperature. The FTIR data also indicated hydroxyl and nitrate groups in the films; these species were removed after annealing in Ar at a temperature of ⩾600 °C. Both FTIR and XRD results indicated the crystallization of pure HfO2 after annealing at temperatures as low as 600 °C. On the other hand, pure Al2O3 remained amorphous after annealing at temperatures up to 800 °C. XRD data of the composite HfAlOx film show that films deposited by alternating five cycles of HfO2 and one cycle of Al2O3 remained amorphous after annealing at 600 °C. Rutherford backscattering analysis of HfAlOx deposited with a varied number of alternating HfO2 and Al2O3 cycles demonstrated a strong correlation between the cyclic dosage of TDEAA and TDEAH and the film composition.


Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1505
Author(s):  
José Rosa ◽  
Mikko J. Heikkilä ◽  
Mika Sirkiä ◽  
Saoussen Merdes

Y2O3:Eu is a promising red-emitting phosphor owing to its high luminance efficiency, chemical stability, and non-toxicity. Although Y2O3:Eu thin films can be prepared by various deposition methods, most of them require high processing temperatures in order to obtain a crystalline structure. In this work, we report on the fabrication of red Y2O3:Eu thin film phosphors and multilayer structure Y2O3:Eu-based electroluminescent devices by atomic layer deposition at 300 °C. The structural and optical properties of the phosphor films were investigated using X-ray diffraction and photoluminescence measurements, respectively, whereas the performance of the fabricated device was evaluated using electroluminescence measurements. X-ray diffraction measurements show a polycrystalline structure of the films whereas photoluminescence shows emission above 570 nm. Red electroluminescent devices with a luminance up to 40 cd/m2 at a driving frequency of 1 kHz and an efficiency of 0.28 Lm/W were achieved.


2018 ◽  
Vol 64 (3) ◽  
pp. 206
Author(s):  
R. S. Castillo Ojeda ◽  
Joel Díaz-Reyes ◽  
M. Galván-Arellano ◽  
K. N. Rivera-Hernández ◽  
M. S. Villa-Ramírez ◽  
...  

In this work are presented the results obtained from the deposition ofCd1-xZnxTe nanolayers using as precursor the vapours of the elementsZn, Te, and a mixture of Cd and Zn on GaAs and GaSb (001) substrates by Atomic Layer Deposition technique (ALD), which allows the deposition of layers of nanometric dimensions. At each exposure of the growth surface to the of cation or anion precursors vapours, this surface is saturated. Therefore, it is considered that the process is self-regulated. The ZnTe layers were grown in a wide range of temperatures; however, ZnTe nanolayers with a shiny mirror-like surface could be grown at temperatures between 370 and 410oC. Temperatures higher than 400oC were necessary for the CdTe growth. The layers of the Cd1-xZnxTe ternary alloy were deposited at temperature range of 400 and 425oC. The grown nanofilms were characterized by Raman spectroscopy and high-resolution X-ray diffraction. The Raman spectrumshows the peak corresponding to LO-ZnTe at 208 cm-1, which is weak and is slightly redshifted in comparison with the reported for the bulk ZnTe. For the case of the CdTe nanolayers, Raman spectrum presents the LO-CdTe peak, which is indicative of the successfully growth of the nanolayers, its weakness and its slight redshifted in comparison with the reported for the bulk CdTe can be related with the nanometric characteristic of this layer. The performed high resolution X-ray diffraction measurements allowed to study some importantcharacteristics, as the crystallinity of the grown layers. Additionally, the performed HR-XRD measurements suggest that the crystalline quality have dependence with the growth temperature.


2019 ◽  
Vol 61 (10) ◽  
pp. 1941
Author(s):  
И.А. Тамбасов ◽  
М.Н. Волочаев ◽  
А.С. Воронин ◽  
Н.П. Евсевская ◽  
А.Н. Масюгин ◽  
...  

Thin films of aluminum doped zinc oxide were grown using atomic layer deposition at a temperature of 200 ° C. Using X-ray diffraction, it was found that thin ZnO: Al films have peaks from the (100), (002), (110) and (201) planes of the hexagonal ZnO phase. The (101) and (102) planes were also detected using electron diffraction. Thin ZnO: Al films grow smooth with a root-mean-square roughness of Rq of 0.33 nm and characteristic nanocrystallite sizes of ~ 70 and ~ 15 nm without additional phases associated with aluminum or aluminum oxides. The transmission at a wavelength of 550 nm, taking into account the substrate, was ~ 96%. The refractive indices and absorption coefficients of thin ZnO: Al films in the wavelength range of 250–900 nm were found. The maximum values ​​for the refractive and absorption coefficients were 2.09 at a wavelength of 335 nm and 0.39 at a wavelength of 295 nm, respectively. The optical band gap was 3.56 eV. The resistivity, the Seebeck coefficient and the power factor of thin ZnO: Al films were ~ 1.02 · 10-3 Ohm · cm, ~ - 60 μV / K and 340 μW · m-1 · K-2 at room temperature, respectively. The maximum power factor reached 620 μW · m-1 · K-2 at a temperature of 200 ° C.


Inorganics ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 113 ◽  
Author(s):  
Xinyu Mao ◽  
Alexandre C. Foucher ◽  
Eric A. Stach ◽  
Raymond J. Gorte

LaCoO3 films were deposited onto MgAl2O4 powders by atomic layer deposition (ALD) and then used as catalyst supports for Pt. X-ray diffraction (XRD) showed that the 0.5 nm films exhibited a perovskite structure after redox cycling at 1073 K, and scanning transmission electron microscopy and elemental mapping via energy-dispersive X-ray spectroscopy (STEM/EDS) data demonstrated that the films covered the substrate uniformly. Catalysts prepared with 3 wt % Pt showed that the Pt remained well dispersed on the perovskite film, even after repeated oxidations and reductions at 1073 K. Despite the high Pt dispersion, CO adsorption at room temperature was negligible. Compared with conventional Pt on MgAl2O4, the reduced forms of the LaCoO3-containing catalyst were highly active for the CO oxidation and water gas shift (WGS) reactions, while the oxidized catalysts showed much lower activities. Surprisingly, the reduced catalysts were much less active than the oxidized catalysts for toluene hydrogen. Catalysts prepared from thin films of Co3O4 or La2O3 exhibited properties more similar to Pt/MgAl2O4. Possible reasons for how LaCoO3 affects properties are discussed.


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