Antireflective layers

Layer Stacks and Protective Layers. The layer stack of an MO disk consists mainly of an MO layer, a dielectric antirefiection layer, and a metallic reflection layer (Fig. 14). The thickness of the antireflection layer as well as that of the MO layer have to be properly chosen to obtain a maximum magnetooptical figure-of-mefit (FOM). The FOM can be further increased by using a quadfilayer configuration with dielectric layers on both sides of the MO layer. Practical disks use the generalized configuration 50—120-nm dielectric layer, 25—90-nm MO layer, 17—70-nm dielectric layer (for quadfilayer configuration only), and 15—150-nm reflective layer. 

Fig. 13. Schematic cross section of Time-Zero SX-70 integral film. In this film the polymeric acid layer and the timing layer are located beneath the negative layers, rather than in the positive sheet. Time-Zero and all later Polaroid integral films have an antireflection layer coated on the outer surface of the clear...

Horn, M. W., Antireflection Layers and Planarization for Microlithography, Solid State Technology, pp. 57-62 (Nov. 1991)... 

A typical semiconductor device (found in the back-end of the line or the interconnects) consists of a layer of glass followed by a sputtered layer of titanium, which is thermally treated to form a titanium silicide. Next, a layer of titanium nitride is deposited on top of the silicide and on the sidewall of the contacts by sputtering or by MOCVD (see Fig. 13.3 in Ch. 13).P ]P ] This layer of TiN acts as a diffusion barrier and an adhesion promoter. It is followed by the main interconnect, which is an aluminum-copper alloy, in turn followed by another layer of TiN, which acts as adhesion and antireflecting layer. 

Figure 4.3 Transmission benefit of porous Si02 antireflection layer. The solar transmittance of a glass sheet increases from 90 to 95%. (Reproduced from Merck.com)...

The scattering effect is exploited in the longitudinal mode, i.e. with the light and applied field directions collinear. The major faces of the plate are coated with ITO electrodes and antireflection layers. The arrangement of the device is shown in Fig. 8.14. 

The substituted garnet plates can be produced by slicing from a single crystal rod grown by the floating zone method or, more economically, from thick films grown onto a host substrate by liquid phase epitaxy (see Section 3.11). The plates are lapped, polished, coated with antireflection layers and then diced to produce the final elements ( 2mm side by 100/mi thickness) ready for assembly into the isolator. 

The photocurrent uniformity for these photosensors is mainly dependent on the antireflection layer thickness and the picture element dimensions. A less than 5% nonuniformity of photocurrent has been obtained. 

It is interesting to note that the first antireflection layer on glass was made incidentally 1817 by Fraunhofer [13] in Germany by treating polished glass with concentrated sulphuric or nitric acid. But no technical application was tried at that time. 

Spectral transmittance of photo objectives uncoated and coated with antireflection layers (Leica, Wetzlar, FRG)... 

Fig. n.8 The structure of an OLED with three organic layers and a dielectric cover layer. HTL refers to the hole transport layer, EML to the emission layer, ETL to the electron transport layer. N, and k, are the optical constants of the layers (for their definitions, see Sect. 11.2.3). The dielectric is an antireflection layer. After [6, 10]. 

Fig. n.n Improvement of the efficiency by means of a ZnSe antireflection layer 60 nm thick. From [10]. 

This already rather high value could be improved further by adding a reflection-reducing ZnSe layer onto the semitransparent cathode. Figure 11.11 shows the efficiency as a function of the operating voltage V, with and without the antireflection layer. With a 60 nm thick ZnSe layer, the efficiency was further increased by about a factor of 2. 

Adamian, Z. N., Hakhoyan, A. E, Aroutiounian, V. M., Barseghian, R.S. and Touryan, K. J. Investigations of solar cells with porons silicon as antireflection layer (2000) Sol. Energy Mater. Sol. Cells, 64,347-51. 

The maximal theoretical efficiency of solar energy conversion (for normal intensity of solar radiation) in silicon solar batteries with one p-n-junction is about 30% (Shockley-Queisser limit, described in 1961). For multijunction tandem solar batteries and for batteries with an optical light condenser the theoretical limit is higher. The practical efficiency is lower and depends on several factors, including the crystalline modification of silicon and the thickness of the semiconductor, where photons are adsorbed. For high thickness silicon batteries the efficiency reaches about 20%. For low thickness batteries made from amorphous silicon it is 5-10%. The maximum practical conversion efficiency silicon has is at a temperature of about 25 C. With rising temperatures the efficiency diminishes. The battery is often covered by a thin layer of silicium nitride that reflects UV light and prevents a temperature rise (antireflection layer). 

Additional novel particles, including nylon 66, alumina, " gold, garnet, diamond, graphite, polyaniline, and boron nitride nanosheets, and nanoparticles of low molecular weight borate esters, have been introduced to increase ionic conductivities. Boron-doped PDMS has been used as scintillators for thermal neutron detection. Nanowires of ZnO have been inserted into PDMS to give tunable, flexible antireflection layers, and ZnO has also been introduced into such polymers as quantum dots. Similarly, color-tunable luminescent... 

Acoustic matching layer Antireflective layer of acoustic wave... 

In order to longitudinally collect the fight, and to guide it as well as possible in the optical fibre, the proposed solution is to successively deposit an antireflective layer on the optical fibre or textile and a reflective layer on the lower half of the fibre or textile. Thus, the obtained solution is close to the desired one, as shown in Fig. 21.17. 

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