Investigation of Antireflection Nb2O5 Thin Films by the Sputtering Method under Different Deposition Parameters

Abstract

In this study, Nb2O5 ceramic was used as the target to deposit the Nb2O5 thin films on glass substrates with the radio frequency (RF) magnetron sputtering method. Different deposition temperatures and O2 ratios were used as parameters to investigate the optical properties of Nb2O5 thin films. The deposition parameters were a pressure of 5 × 10−3 Torr, a deposition power of 100 W, a deposition time of 30 min, an O2 ratio (O2/(O2 + Ar), in sccm) of 10% and 20%, and deposition temperatures of room temperature (RT), 200, 300 and 400 °C, respectively. We found that even if the deposition temperature was 400 °C, the deposited Nb2O5 thin films revealed an amorphous phase and no crystallization phase was observed. The optical properties of transmittance of Nb2O5 thin films deposited on glass substrates were determined by using a ultraviolet-visible (UV-vis) spectrophotometer (transmittance) and reflectance spectra transmittance (reflectance, refractive index, and extinction coefficient) in the light wavelength range of 250–1000 nm. When the O2 ratio was 10% and the deposition temperature increased from RT to 200 °C, the red-shift was clearly observed in the transmittance curve and the transmission ratio had no apparent change with the increasing deposition temperature. When the O2 ratio was 20%, the red-shift was not observed in the transmittance curve and the transmission ratio apparently decreased with the increasing deposition temperature. The variations in the optical band gap (Eg) values of Nb2O5 thin films were evaluated from the Tauc plot by using the quantity hν (the photon energy) on the abscissa and the quantity (αhν)r on the ordinate, where α is the optical absorption coefficient, c is the constant for direct transition, h is Planck’s constant, ν is the frequency of the incident photon, and the exponent r denotes the nature of the transition. As the O2 ratio of 10% or 20% was used as the deposition atmosphere, the measured Eg values decreased with the increase of the deposition temperature. The reflectance ratio, extinction coefficient, and refractive index curves of Nb2O5 thin films were also investigated in this study. We would show that those results were influenced by the deposition temperature and O2 ratio.

Development of the α-IGZO/Ag/α-IGZO Triple-Layer Structure Films for the Application of Transparent Electrode

“…Small grains in the α-IGZO/Ag/α-IGZO triple-layer structure appeared as the Ag thickness grew larger than 11.5 nm. The average particle sizes of nano-crystallization α-IGZO grains can be calculated using the following equation [ 28 ]: G = −2.9542 + 1.4427 ln( N ) where G is the number of grains per unit area at a particular magnification, N is the number of grains/mm 2 . As the thicknesses of Ag film was 11.5 nm-, 13 nm-, 14.5 nm-, and 16 nm, the average particle sizes of nano-crystallization grains were about 35.8 nm, 39.6 nm, 43.5 nm, and 54.3 nm, respectively, as shown in Figure 1 b–e.…”

Optical Properties of Porous Alumina Assisted Niobia Nanostructured Films–Designing 2-D Photonic Crystals Based on Hexagonally Arranged Nanocolumns

“…The optical, structural, and electrochromic properties of the different crystalline polymorphic forms of the niobia films make them attractive for optical applications [ 19 , 20 ]. There are various methods for the oxide materials synthesis, in particular, alumina and niobia: the metal thermal oxidation with oxygen to obtain an oxide in the highest oxidation state [ 18 , 21 ] and metal subsequent sintering (sinter) with higher oxide in vacuum in required proportion to obtain oxides in an intermediate oxidation state [ 20 ], spray pyrolysis deposition [ 22 , 23 ], atomic-layer deposition [ 24 , 25 ], and plasma-enhanced atomic layer deposition [ 26 ], magnetron sputtering technique [ 18 , 27 , 28 , 29 ], and reactive magnetron sputter process [ 30 ], chemical precipitation from solution [ 18 , 31 ], the controlled precipitation method [ 16 ], sol-gel method [ 4 , 10 , 18 , 32 , 33 ], polymeric precursors (Pechini) method [ 32 ], hydro-thermal (in water) and solvothermal (in other solvents such as acetone and isopropyl alcohol) synthesis techniques [ 18 ], extraction from natural minerals [ 4 ], chemical vapor deposition [ 19 , 34 ], and plasma-enhanced chemical vapor deposition [ 35 ], pulsed laser deposition [ 36 , 37 , 38 ], electron beam evaporation [ 22 ], molecular beam epitaxy [ 39 ], electrodeposition [ 18 ].…”

Influence of the Characteristics of Multilayer Interference Antireflection Coatings Based on Nb, Si, and Al Oxides on the Laser-Induced Damage Threshold of ZnGeP2 Single Crystal

“…Currently, there are many film-forming materials that can cover a wide range from UV to mid-IR. Several materials, such as Ta 2 O 5 , Nb 2 O 5 , SiO 2 , HfO 2 , YbF 3 , ZnS, Al 2 O 3 , etc., have high transparency and low absorption coefficients in the mid-IR region of the spectrum from 2 to 13 µm [18][19][20][21][22]. These materials are being actively studied and are the most promising as film-forming materials for the development of antireflection coatings and dielectric mirrors with high radiation resistance.…”