Amorphous ultra-wide bandgap ZnOx thin films deposited at cryogenic temperatures

Abstract

Crystalline wurtzite zinc oxide (w-ZnO) can be used as a wide band gap semiconductor for light emitting devices and for transparent or high temperature electronics. The use of amorphous zinc oxide (a-ZnO) can be an advantage in these applications. In this paper we report on X-ray amorphous a-ZnOx thin films (~500 nm) deposited at cryogenic temperatures by reactive magnetron sputtering. The substrates were cooled by a nitrogen flow through the copper substrate holder during the deposition. The films were characterized by X-ray diffraction (XRD), Raman, infrared, UV-Vis-NIR spectroscopies, and ellipsometry. The a-ZnOx films on glass and Ti substrates were obtained at the substrate holder temperature of approximately -100C. New vibration bands at 201, 372, and 473 cm -1 as well as O-H stretch and bend absorption bands in the a-ZnOx films were detected by FTIR spectroscopy. Raman spectra showed characteristic ZnO2 peaks at 386 and 858 cm -1 attributed to the peroxide ion O2 2stretching and libration modes, respectively. In addition, the films contain neutral and ionized O2 and O2species. The a-ZnOx films are highly transparent in the visible light range (≈87%) and exhibit a refractive index of 1.68 at 2.25 eV (550 nm). An optical band gaps is 4.65 eV with an additional band edge 2 absorption feature at 3.50 eV. It has been shown that the deposition on actively cooled substrates can be a suitable technique to obtain low temperature phases that cannot be deposited at room temperature.

Amorphous WO3 thin films designed as gigahertz/terahertz dielectric lenses

“…Amorphous films of WO3 are mentioned beneficial for fabrication of supper capacitors [3] and as anodes for Li-ion batteries [7]. Amorphous films play important role in device fabrication because they are able to provide several advantages over crystalline ones like higher uniformity and better compatibility with flexible substrates [8]. On the other hand, Fig.…”

Optical properties of oxygen-containing yttrium hydride thin films during and after the deposition

“…In the case of absorption tales (at E < Eg) present in the extinction coefficient dispersion curves (like for the YHxOy films given in the Fig. 7(b)), Eg obtained from TLO are underestimated even for amorphous materials [43,44]. HJPS oscillator function offers precision in Eg evaluation for any material even with absorption tale's issues.…”

Enhanced Reflectivity Change and Phase Shift of Polarized Light: Double Parameter Multilayer Sensor

“…The fabrication process and characteristics of ZnO x thin films can be found in our reference. [ 35 ] The YHO thin films were fabricated on soda‐lime glass using the vacuum PVD coater G500M (Sidrabe Vacuum, Ltd.). YHO films were deposited by reactive DC magnetron sputtering from Y (purity 99.95%) target in an Ar (99.9999%) and H 2 (99.999%) atmosphere (H 2 to Ar gas flow ratio of 2:3).…”

“…In the simulations we use the complex dielectric dispersion curves obtained from WOOLLAM RC2 SE investigations for YHO and ZnOx [28] thin films developed at the Thin Film Laboratory of ISSP UL. The fabrication process and characteristics of ZnOx thin films can be found in our reference [35] . The YHO thin films were fabricated on soda-lime glass using the vacuum PVD coater G500M (Sidrabe Vacuum, Ltd.).…”