Proposed Correction of Calculated physical Quantities for Multi-Layer Thin Films (One-Dimensional Photonic Crystals)

There has been much interest in photonic and spectroscopic devices that are useful for controlling transmission and reflection coefficients such as multilayer thin films, photonic crystals, and various Bragg structures in the form of molds or multilayer thin films.

Fabricating Photonic Crystals and Their Characterization

Photonic crystals is a low-loss periodic medium with periodic changes of refractive index, which is used to control the light. Theoretically, Photonic crystals can be studied using Maxwell equations, but it’s difficult to find a general analytical solution for these equations, since we are dealing with vectors. So we resort to the numerical solutions for Maxwell’s equations to calculate the reflection and transmission coefficients and the Photonic band gap.

Laser Deposition of SnO2 Thin Films by Continuous CO2 Laser and Their Characterizations

There are wide uses of tin oxide thin films, especially in the field of transparent conductors, solar cells, gas sensors and piezoelectric materials. Laser deposition is considered one of the most important techniques followed to obtain these films. In this research, we develop a technique to obtain homogeneous thin films of tin oxide depending on vaporization of pile targets of this oxide by continuous CO2 laser in the atmosphere, with a fan which guarantees obtaining homogenous films. Some of these films were annealed in different conditions. The optical microscope images revealed the presence of high degree of homogeneity, while the X-Ray study showed different crystallization grain orientations which depend on the preparation conditions. The preferred direction is (110). The optical absorption gives information about the value of the effective band gal for the samples before and after thermal annealing. We have found that some films have Eg = 3.2 ev. before annealing, and after long annealing they have Eg=1.3ev. In addition, the hard annealed thin films reveal anisotropy in the optical and electrical. Characteristics, they have different absorption coefficients in two perpendicular directions, also there is an electrical resistance anisotropy along these two directions especially after hard annealing. The Eb was 0.73 ev before annealing, it became 0.37 ev for one direction and 0.32 ev for the other direction.