Anti-reflection layers

Ogawa, A. Sekiguchi, and N. Yoshizawa, Advantages of a SiO NyiH anti reflective layer for ArF excimer laser lithography, Jpn. J. Appl. Phys. 35 6360 (1996). 

The second strategy was more complicated and involved the lamination of alhin anti reflective layer onto a suitably transparent textile material followed by plasma, thermal or chemical treatment. The next successive step focuses on application of a photoanode electrode onto the textile material. Subsequent procedure led to the deposition of the active material and finally evaporation of the cathode electrode complete the device as a textile PV composed of organic, inorganic and also their composites. 

We will also briefly discuss anti-reflection layers. A surface without any special preparation between an external medium (frequently air), with refractive index ng, and an optical component with refractive index n, has a reflectivity R given by... 

Figure 16.9 Porous coating acting as an anti reflection layer with low refractive index.

The implementation of so-called back-thinned CCD removes sensitivity limitations of classical front-illuminated and UV-coated CCD. Using this improved technology, the substrates with extremely thin silica layers are back-illuminated and a large increase in quantum efficiency in the UV range up to 0.9 electrons per photon can be achieved. Specific anti-reflection layers on the detector surface produce further enhancement of the detector efficiency for certain spectral bands. 

Kesmez, O., Erdem Camurlu, H., Burunkaya, E. and Arpac, E. (2009) Sol-gel preparation and characterization of anti-reflective and self-cleaning Si02-Ti02 double-layer nanometric films. Solar Energy Materials and Solar Cells, 93, 1833-1839. 

A substrate 10 of HgCdTe is provided with an upper surface region 11 formed by an annealing procedure, or as an epitaxial layer or evaporated film. A layer of insulating material 12 is formed in which windows are provided. The windows are partially filled with a thin layer of metal 13 which is deposited therein to form a metal-semiconductor diode with the upper surface region. The metal layer is deposited to a thickness on the order of 10-50 nm thick and is sufficiently thin to be semi-transparent to infrared radiation. A thick layer of metal 14 is deposited to form an expanded contact and an anti-reflection coating 15 is provided. External conductors in the form of jumper wires 16 are ball bonded to the contact 14. 

Modern technological developments and many fields of pure and applied research depend on the quantitative information about the spatial element distribution in thin solid layers and thin-film systems. For example, without the use of thin films the experimental studies on the physics of semiconductor are very difficult. Similarly the diffusion processes in solids, sandwich-like thin films structures in microelectronics, anti-reflecting or selectively transparent optical films, catalysts, coatings, composites - all rely on material properties on an atomic scale. The development of these new materials as well as the understanding of the basic physical and chemical properties that determine their specific characters are not possible without the knowledge of their compositional structure, in particular in the interface regions. 

In Chapter 9 properties of antireflection coatings were examined. At that time the simplified case of a single film separating air and a substrate was considered. Here the discussion is on how such a film might be produced. Acmal films, such as the anti-reflective coatings on the lenses found in eyeglasses, contain multiple layers plus a protective coating. 

Compositions for an anti-reflective light-absorbing layer using diazoquinones, (III), were prepared by Yoon [2] and used in forming patterns in semiconductor devices. 

As a last feature we will discuss the slight oscillations added to the spectrum measured with the chip-size spectrometer. These are caused by Fabiy-Perot oscillations within the protection layer on top of the CMOS chip in the camera. An appropriate anti-reflection coating on top of the protection layer will efficiently remove this artifact. Moreover, for a real device the protection layer will be replaced by depositing the graded filter directly on top of the CMOS chip. 

---