Thickness Dependence Of Optical Properties Research Articles

Thickness dependence of optical properties of sputtered AZO film on borosilicate glass

Sputtered AZO film with different thicknesses (98, 141, 206, 249 and 306 nm) was deposited on a borosilicate substrate. The XRD pattern indicated that the deposited AZO films showed the prominent peak of the AZO phase in the (002) direction, and the (004) plane was also observed on the 141, 206, 249 and 306 nm films. The peak intensity was increased with film thickness. AFM images reveal that all films show a granule surface and columnar structure with different sizes and distributions depending on thickness. In addition, the surface roughness and electrical resistance of the films were increased with increasing thickness. The 98 nm film exhibited a constant transmission, but the optical transmission of the rest of the films fluctuated with the wavelength in the 400-1000 nm range, and their transmission was thickness-dependent. The maximum mobility and carrier concentration was observed on the 306 and 249 nm, respectively. The energy bandgap of the film ranged from 3.5-3.6 eV and was increased with the film thickness. The results attribute that the thickness significantly modifies structural phase, surface morphology, and roughness, strongly affecting the optical properties of sputtered AZO films.

Layer thickness-dependent optical properties of GaTe

Gallium Telluride (GaTe) has emerged as a potential candidate for optoelectronic applications due to its outstanding optical properties. However, a comprehensive understanding of the thickness-dependent optical properties, particularly the bandgap and vibration modes, is still lacking. In this study, we investigated the dependence of bandgap and Raman-active modes on layer thickness by measuring micro-photoluminescence (PL) and micro-Raman spectroscopy of GaTe at 77 K. Our results revealed a significant dependence of bandgap and Raman-active modes on layer thickness, with the bandgap of GaTe flakes increasing from 1.736 to 2.09 eV as the thickness decreases from bulk to 1.5 nm. Furthermore, the quantum confinement effect led to a direct to indirect bandgap transition in few-layered GaTe. We also interpret interlayer coupling and long-range Coulomb interactions between layers resulted in the appearance of an extra Raman peak associated with the shear or breathing modes and structural change for GaTe-flakes with decreasing their thickness down to a few layers. Additionally, we observed a softening of Ag3, Ag4, and Ag5 modes and stiffening of others with reducing thickness. Our results provide a comprehensive understanding of the thickness dependence of optical properties in GaTe material.

Thickness dependence of optical properties of thin multilayer Ag/Bi structures and their surface plasmon-enhanced photoluminescence capability

Preparation technology, optical properties and surface-enhanced photoluminescence features of thin Ag/Bi layers with different ratios of the chemical elements are subject of present work. Coatings with different number of Ag/Bi stacks were tested in order to determine the minimum number of sublayers required to achieve epsilon-near-zero properties (ENZ). The results for the complex permittivity showed that the Ag/Bi films possess epsilon-near-zero properties in a wide spectral range of 1.3-6 eV. It was established that the most promising material for photoluminescence signal amplification is the four stacked Ag50:Bi50 thin layer.

Thickness dependence of optical properties of amorphous indium oxide thin films deposited by reactive evaporation

AbstractThe electrical conductivity and absorption coefficient of amorphous indium oxide thin films, thermally evaporated on glass substrates at room temperature, were evaluated. For direct transitions the variation of the optical band gap with thickness was determined and this variation was supposed to appear due to the variation of localized gap states, whereas the variation of conductivity with thickness was supposed to be due to the variation of carrier concentration. We attribute the variation of absorption coefficient with thickness to the variation of optical band gap energy rather than optical interference. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Thickness dependence of optical properties of VO 2 thin films epitaxially grown on sapphire (0 0 0 1)

Vanadium dioxide (VO 2) films were epitaxially grown on α-Al 2O 3 (0 0 0 1) by rf reactive magnetron sputtering. The effects of film thickness ranging from 3 to 150 nm on optical properties were investigated. It revealed that the semiconductor–-metal phase transition temperature considerably decreases as film thickness decreases, in particular for the film with thickness less than 10 nm. On the other hand, we found that the difference in visible transmittance between the two phases of VO 2 also varies with film thickness. For the films with thickness less than 50 nm, the semiconductor phase exhibits lower visible transmittance than its metallic phase, while for those with thickness larger than 50 nm the situation is reversed.

Barrier thickness dependence of optical properties in GaAs coupled quantum wires

Barrier thickness dependences, namely coupling strength dependences, of optical properties in GaAs coupled quantum wires are investigated by the photoluminescence (PL), photoluminescence excitation (PLE) and radiative lifetime measurements. In the photoluminescence characteristics, the coupled states of symmetric and antisymmetric states are clearly observed with large barrier thickness dependence. Also, the temperature dependence of the radiative lifetime shows a barrier thickness dependence which might be due to the difference of the oscillator strength in the coupled quantum wires with different barrier thicknesses.

Thickness dependence of optical properties of hydrogenated amorphous silicon films

A detailed study of the thickness dependence of optical constants of glow discharge prepared hydrogenated amorphous silicon thin films (a-Si:H) is reported in this paper. The thicknesses of the films range from 0.32 to 1.77 μm. The optical constants, refractive index n( λ), absorption coefficient α( λ), extinction coefficient ( k( λ) and consequently the real and imaginary parts of the dielectric constant and the optical bandgap, are determined from the transmission spectrum alone, obtained over the wavelength region of 550 nm to 900 nm by means of a spectrophotometer. The absorption coefficient α, refractive index n and the extinction coefficient k are found to increase for thinner films (0.32 to 0.9 μm) and showed apparently little change for thicker films (above 0.9 μm). The bandgap E g, calculated from both (ahν) 1 2 versus hv and (ε ″) 1 2 versus hv, is found to increase with increasing film thickness. Activated electrical conduction also showed an increase in the fermi level for increasing film thickness. These results are discussed in terms of the quality of the films.