scholarly journals Atomic Layer Deposition of Superconducting CuO Thin Films on Three-Dimensional Substrates

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 650
Author(s):  
Aile Tamm ◽  
Aivar Tarre ◽  
Valeriy Verchenko ◽  
Helina Seemen ◽  
Raivo Stern

In previous decades, investigation of superconductors was aimed either at finding materials with higher critical temperatures or at discovering nontypical superconducting behavior. Here, we present the cupric (CuO) thin films, which were synthesized by atomic layer deposition by using a metal-organic precursor, copper (II)-bis-(-dimethylamino-2-propoxide), and ozone as an oxidizer. The deposition process was optimized by employing a quartz crystal monitoring, and the contact between the deposited films and planar and three-dimensional SiO2/Si substrates was examined by scanning electron microscopy with a focused ion beam module. Phase and elemental composition were analyzed by X-ray diffraction and X-ray fluorescence. Two-probe electrical resistivity measurements revealed a resistivity drop below the critical temperature of 4 K, which may indicate low-temperature superconductivity of the CuO thin films.

2019 ◽  
Vol 217 (8) ◽  
pp. 1900237
Author(s):  
Zhen Zhu ◽  
Saoussen Merdes ◽  
Oili M. E. Ylivaara ◽  
Kenichiro Mizohata ◽  
Mikko J. Heikkilä ◽  
...  

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 136 ◽  
Author(s):  
Zhigang Xiao ◽  
Kim Kisslinger ◽  
Sam Chance ◽  
Samuel Banks

We report the growth of nanoscale hafnium dioxide (HfO2) and zirconium dioxide (ZrO2) thin films using remote plasma-enhanced atomic layer deposition (PE-ALD), and the fabrication of complementary metal-oxide semiconductor (CMOS) integrated circuits using the HfO2 and ZrO2 thin films as the gate oxide. Tetrakis (dimethylamino) hafnium (Hf[N(CH3)2]4) and tetrakis (dimethylamino) zirconium (IV) (Zr[N(CH3)2]4) were used as the precursors, while O2 gas was used as the reactive gas. The PE-ALD-grown HfO2 and ZrO2 thin films were analyzed using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). The XPS measurements show that the ZrO2 film has the atomic concentrations of 34% Zr, 2% C, and 64% O while the HfO2 film has the atomic concentrations of 29% Hf, 11% C, and 60% O. The HRTEM and XRD measurements show both HfO2 and ZrO2 films have polycrystalline structures. n-channel and p-channel metal-oxide semiconductor field-effect transistors (nFETs and pFETs), CMOS inverters, and CMOS ring oscillators were fabricated to test the quality of the HfO2 and ZrO2 thin films as the gate oxide. Current-voltage (IV) curves, transfer characteristics, and oscillation waveforms were measured from the fabricated transistors, inverters, and oscillators, respectively. The experimental results measured from the HfO2 and ZrO2 thin films were compared.


2019 ◽  
Vol 9 (10) ◽  
pp. 1990 ◽  
Author(s):  
Jinseong Ahn ◽  
Changui Ahn ◽  
Seokwoo Jeon ◽  
Junyong Park

Atomic layer deposition (ALD) is a unique tool for conformally depositing inorganic thin films with precisely controlled thickness at nanoscale. Recently, ALD has been used in the manufacture of inorganic thin films using a three-dimensional (3D) nanonetwork structure made of polymer as a template, which is pre-formed by advanced 3D nanofabrication techniques such as electrospinning, block-copolymer (BCP) lithography, direct laser writing (DLW), multibeam interference lithography (MBIL), and phase-mask interference lithography (PMIL). The key technical requirement of this polymer template-assisted ALD is to perform the deposition process at a lower temperature, preserving the nanostructure of the polymer template during the deposition process. This review focuses on the successful cases of conformal deposition of inorganic thin films on 3D polymer nanonetworks using thermal ALD or plasma-enhanced ALD at temperatures below 200 °C. Recent applications and prospects of nanostructured polymer–inorganic composites or hollow inorganic materials are also discussed.


2014 ◽  
Vol 565 ◽  
pp. 277-284 ◽  
Author(s):  
Peng Wang ◽  
Michael R. Hudak ◽  
Allan Lerner ◽  
Robert K. Grubbs ◽  
Shanmin Wang ◽  
...  

2017 ◽  
Vol 727 ◽  
pp. 907-914
Author(s):  
Wen Hui Tang ◽  
Yi Jia ◽  
Bo Cheng Zhang ◽  
Chang Wei Yang ◽  
You Zhi Qu ◽  
...  

Polycrystalline GaN thin films were successfully grown at low temperature (250 °C) by plasma-enhanced atomic layer deposition with NH3, N2, N2/H2 gas mixture and trimethylgallium (TMG) as precusor. The growth rate, crystal structure, surface composition and the valence state of the corresponding element of the GaN thin films using different nitrogen sources were characterized and examined systematically via the spectroscopic ellipsometry, the x-ray diffractometer, the x-ray photoel-ectron spectrometer. It is showed that all the GaN thin films using different nitrogen sources were polycrystalline structure and the preffered orientation were mainly (100). The films using N2 and N2/H2 gas mixture had a higher crystal quality than films using NH3. The GPC (growth rate per cycle) would increase with the increase of the N2 flow rate. The films using a suitable ratio of N2/H2 flow rate had not only a high GPC but a good crystal quality. The ratios of Ga/N element of the films using N2/H2 gas mixture were approximated to 1:1, it would increase with the ratio of the N2/H2 flow rate in the gas mixture, which is showing much effect of the ratios of N2/H2 flow rate on the nitrogen content of the thin films.


2019 ◽  
Vol 10 ◽  
pp. 1443-1451
Author(s):  
Ivan Kundrata ◽  
Karol Fröhlich ◽  
Lubomír Vančo ◽  
Matej Mičušík ◽  
Julien Bachmann

Lithiated thin films are necessary for the fabrication of novel solid-state batteries, including the electrodes and solid electrolytes. Physical vapour deposition and chemical vapour deposition can be used to deposit lithiated films. However, the issue of conformality on non-planar substrates with large surface area makes them impractical for nanobatteries the capacity of which scales with surface area. Atomic layer deposition (ALD) avoids these issues and is able to deposit conformal films on 3D substrates. However, ALD is limited in the range of chemical reactions, due to the required volatility of the precursors. Moreover, relatively high temperatures are necessary (above 100 °C), which can be detrimental to electrode layers and substrates, for example to silicon into which the lithium can easily diffuse. In addition, several highly reactive precursors, such as Grignard reagents or n-butyllithium (BuLi) are only usable in solution. In theory, it is possible to use BuLi and water in solution to produce thin films of LiH. This theoretical reaction is self-saturating and, therefore, follows the principles of solution atomic layer deposition (sALD). Therefore, in this work the sALD technique and principles have been employed to experimentally prove the possibility of LiH deposition. The formation of homogeneous air-sensitive thin films, characterized by using ellipsometry, grazing incidence X-ray diffraction (GIXRD), in situ quartz crystal microbalance, and scanning electron microscopy, was observed. Lithium hydride diffraction peaks have been observed in as-deposited films by GIXRD. X-ray photoelectron spectroscopy and Auger spectroscopy analysis show the chemical identity of the decomposing air-sensitive films. Despite the air sensitivity of BuLi and LiH, making many standard measurements difficult, this work establishes the use of sALD to deposit LiH, a material inaccessible to conventional ALD, from precursors and at temperatures not suitable for conventional ALD.


Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2434
Author(s):  
Aaron J. Austin ◽  
Elena Echeverria ◽  
Phadindra Wagle ◽  
Punya Mainali ◽  
Derek Meyers ◽  
...  

Silica nanosprings (NS) were coated with gallium nitride (GaN) by high-temperature atomic layer deposition. The deposition temperature was 800 °C using trimethylgallium (TMG) as the Ga source and ammonia (NH3) as the reactive nitrogen source. The growth of GaN on silica nanosprings was compared with deposition of GaN thin films to elucidate the growth properties. The effects of buffer layers of aluminum nitride (AlN) and aluminum oxide (Al2O3) on the stoichiometry, chemical bonding, and morphology of GaN thin films were determined with X-ray photoelectron spectroscopy (XPS), high-resolution x-ray diffraction (HRXRD), and atomic force microscopy (AFM). Scanning and transmission electron microscopy of coated silica nanosprings were compared with corresponding data for the GaN thin films. As grown, GaN on NS is conformal and amorphous. Upon introducing buffer layers of Al2O3 or AlN or combinations thereof, GaN is nanocrystalline with an average crystallite size of 11.5 ± 0.5 nm. The electrical properties of the GaN coated NS depends on whether or not a buffer layer is present and the choice of the buffer layer. In addition, the IV curves of GaN coated NS and the thin films (TF) with corresponding buffer layers, or lack thereof, show similar characteristic features, which supports the conclusion that atomic layer deposition (ALD) of GaN thin films with and without buffer layers translates to 1D nanostructures.


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