Trilayer Stacks Research Articles

Polarizing properties of embedded symmetric trilayer stacks under conditions of frustrated total internal reflection: erratum

Polarizing properties of embedded symmetric trilayer stacks under conditions of frustrated total internal reflection: erratum

Influence of capping layers on the crystallization of doped SbxTe fast-growth phase-change films

Isothermal crystallization of doped SbxTe fast-growth phase-change films, with and without capping layers, was investigated using transmission electron microscopy, which provided direct and quantitative information on nucleation and growth processes separately. Two types of amorphous dielectric layers, ZnS–SiO2 and GeCrN, were used for sandwiching the SbxTe films to form typical trilayer stacks, which are the active part in applications. The nucleation and growth parameters of SbxTe films were found to be influenced by the dielectric capping layers. The crystal growth rate is temperature dependent and it reduces when the film is sandwiched between the dielectric layers. The reduction in growth rate differs with the capping layer type. The capping layer influence on the growth rate is pronounced at lower temperatures ∼160°C, but tends to vanish at higher temperatures ∼200°C. The activation energy for crystal growth is 2.4±0.3eV for an uncapped film and it increases ∼40% when the capping layers, GeCrN or ZnS–SiO2, are added. A temperature and time dependent nucleation rate is found and it is accelerated ∼1.7 times by GeCrN layers, whereas it is retarded ∼5 times by ZnS–SiO2 layers. The activation energy for crystal nucleation is 6.1±0.4eV for an uncapped film and it is not noticeably altered by the capping layers. These variations observed in the crystallization kinetics are attributed to variations in interface energy between the phase-change film and the capping layers or vacuum and the confinement effect by the capping layers on the phase-change film.

Polarizing properties of embedded symmetric trilayer stacks under conditions of frustrated total internal reflection

An all-transparent symmetric trilayer structure, which consists of a high-index center layer coated on both sides by a low-index film and embedded in a high-index prism, can function as an efficient polarizer or polarizing beam splitter under conditions of frustrated total internal reflection over a wide range of incidence angles. For a given set of refractive indices, all possible solutions for the thicknesses of the layers that suppress the reflection of either the p or s polarization at a specified angle, as well as the reflectance of the system for the orthogonal polarization, are determined. A 633 nm design that uses a MgF2-ZnS-MgF2 trilayer embedded in a ZnS prism achieves an extinction ratio (ER) > 40 dB from 50 degrees to 80 degrees in reflection and an ER > 20 dB from 58 degrees to 80 degrees in transmission. IR polarizers that use CaF2-Ge-CaF2 trilayers embedded in a ZnS prism are also considered.

Giant magnetoimpedance in trilayer structures of patterned magnetic amorphous ribbons

We have measured the giant magnetoimpedance (GMI) and giant magnetoresistance (GMR) of Metglas®/Cu/Metglas trilayer stacks of micropatterned amorphous magnetic Metglas 2714a ribbons and Cu foils. We obtain room-temperature GMI ratios [Z(0)−Z(Hs)]/Z(Hs) up to 800%, and GMR ratios [R(0)−R(Hs)]/R(Hs) up to 2400% at frequencies of 100 kHz–10 MHz, with Hs the magnetic field in which impedance and resistance saturate towards their minimum values. These high values are a direct consequence of the large dynamic relative permeability of the magnetic ribbons and the chosen trilayer geometry. We analyze our results in the context of a theoretical model of L. V. Panina and K. Mohri [Sens. Actuators A 81, 71 (2000)].

Copper alloy formation and film properties after annealing of Al/Cu stacks in different ambients

In this work, the improvement of MOCVD Cu properties by alloy formation was investigated. Sequential deposited Al/Cu bilayer and Al/Cu/Al trilayer were annealed at 230–450°C in vacuum and H 2. Additionally, the trilayer was annealed in N 2. Vacuum annealing of both bilayer and trilayer stacks results in significant interdiffusion of Al into Cu and remarkable resistivity increase accompanied with much better adhesion. A strong adhesion coupled with a moderate resistivity increase was found for the trilayer annealing in N 2, being a promising approach for fabrication of copper alloy metallization. H 2 annealing provides sufficient adhesion only for the trilayer and only at a very high temperature (400°C). The sheet resistance of all differently processed wafers were stable during half-year-storage except for one sample. The different results between the tested annealing ambients are discussed in detail in this paper.