Antireflection coatings structure

The wafers are processed into solar cells, the majority of which have a diode structure, as sketched in Figure 11.4, characterized by a thin, diffused, doped emitter, screen-printed front and back contacts and a front-surface antireflective coating. Prior to the effective cell manufacturing step, a chemical treatment of the silicon wafers removes... 

The interfaces of importance in SECS are the solid/solid (S/S), solid/gas (S/G), and solid/ liquid (S/L) (4). The area-intensive nature of SECS components was established in the previous section. The major problem is collecting solar energy at a cost that is competitive with other energy forms. Thus, low initial cost is required for the materials, support structures, and production processes in the SECS of interest in Fig. 1 (6). This requires, for example, using thin films in mirrors, in photovoltaic systems, for antireflection coatings on windows, for passive collection, etc. in addition, these films must be made from inexpensive, durable, and easily processed materials (5). Inexpensive long-life materials in flat-plate collectors and durable, stable absorber coatings are also necessary. 

Another structure that has been used to make relatively efficient a-Si H solar cells is shown in Fig. 6b. In this case, the p layer is deposited on a steel substrate, and indium tin oxide (ITO) is electron-beam evaporated onto the flayer. The ITO serves as both a top contact layer and an antireflection coating. The steel substrate may be coated with Cr to improve the back surface reflection. Generally, in all p-i-n cells the top doped layer is thin (— 10 nm) in order to minimize losses due to absorption and recombination in that layer. 

Hamano et al. (1982) have fabricated an a-Si H photodiode array linear image sensor. The sensor structure is shown in Fig. 5. The sensor is constructed by first forming individual electrodes on a glass or a ceramic substrate. Then l-/mi-thick undoped a-Si H is produced at 230°C by glow-discharge decomposition of silane and finally 1500-A-thick ITO common electrode, which also acts as an antireflection coating, is deposited by dc sputtering. 

FIGURE 22 Semiconductor optical amplifier structures Antireflection coated, buried facets, and angle striped. 

X. Li, J. Gao, L. Xue, Y. Han, Porous polymer films with gradient-refractive-Index structure for broadband and omnidirectional antireflection coatings. Advanced Functional Materials 20 (2010) 259-265. 

Vinod PN (2009) Specific contact resistance and carrier tuimeling properties of the silver metal/ porous silicon/p-Si ohmic contact structure. J Alloys Compd 470 393-396 Vinod PN (2013) The fire-through processed screen-printed Ag thick film metal contacts formed on an electrochemically etched porous silicon antireflection coating of silicon solar cells. RSC Adv 3 3618-3622... 

Figure 16.7 Single layer antireflection coating, (a) Schematic structure and working principle (b) simulated reflectance spectrum with refractive indices of 1.52 and 1.38 for the substrate and the film, respectively (no dispersion assumed).

An approach that can be generally applied to various multilayer structures is the well-known transfer matrix technique [87, 180]. It can be used regardless of the geometry of the layers or the intended application of the multilayer. Besides being usable for the calculation of quarterwave Bragg mirrors, it can be used without modification to accurately determine the properties of antireflection coatings, step-down structures, various quasiperiodic, aperiodic and random stractures, but also 2D and 3D photonic crystals as well [241]... 

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