Texture Morphology of SnO₂:F Films and Cell Reflectance

Abstract

The texture formation on the surface of SnO2:F films was carried out using a four component CVD reaction system with tin tetrachloride as a main source. The texture up to about 30% in terms of the haze value could be formed by selecting CVD parameters. It was found in the transmission measurement of hazy SnO2:F films that a part of incident light escaped from the cut edges of the glass substrate even if the integration sphere was used. A nondestructive immersion method is proposed. This enables more exact evaluation of light quantity effectively transmitted to the active part of the a-Si solar cell when it is combined with the reflectance measurement of a pseudocell. It was also found that the reflectance of pseudocells decreased as the haze value increased, and as the shape of grains became sharper when the haze values were similar.

Plasma Textured Glass Surface Morphologies for Amorphous Silicon Thin Film Solar Cells-A review

“…Effective light scattering not only enhances the current density of a-Si TFSCs but also saves cost by making thinner solar cells [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. To obtain textured TCO surface morphologies, various strategies have been applied in the solar cell industry.…”

“…Figure 1 shows various light trapping surface morphologies for the TCO films. Figure 1(a) and 1(b) represents textured TCO surface morphologies of SnO 2 :F and ZnO:B films being employed by the Ashai-U research group [46,[56][57][58][59][60][61]. The ZnO:B films were grown by low pressure CVD (LP-CVD) from precursors of diethyl-zinc and H 2 O; the conductivity was easily controlled by using di-borane as the dopant source [58,59] [1,6,7].…”

Applications of Oxide Coatings in Photovoltaic Devices

“…Generally, thermally grown silicon oxide thin films are denser than those grown by either PECVD or sputtering and thus are better diffusion barriers [45]. However, CVD growth leads to denser SiO 2 films than either sol gel processed or evaporated SiO 2 [46]. PECVD grown silicon oxide films using silane and oxygen sources such as CO 2 and nitrous oxide are usually oxygen poor and thus the refractive indices are usually higher than the value of 1.46 for bulk SiO 2 [13,41,45].…”

“…In thin film silicon pin PV cells, oxides are used for different functionalities. Usually a SiO 2 [46] or SiON x barrier layer grown between the glass and front electrode is used as an anti-reflection coating and as a barrier to sodium diffusion from the soda lime glass substrate. Since the front electrode of thin film silicon pin PV cell, must be both highly conductive and transparent for visible and infra-red light, transparent conducting oxides such as ZnO:Al [97], ZnO:B [30], ZnO:Ga [29] and SnO 2 :F [29,46] are used for this purpose.…”

“…Usually a SiO 2 [46] or SiON x barrier layer grown between the glass and front electrode is used as an anti-reflection coating and as a barrier to sodium diffusion from the soda lime glass substrate. Since the front electrode of thin film silicon pin PV cell, must be both highly conductive and transparent for visible and infra-red light, transparent conducting oxides such as ZnO:Al [97], ZnO:B [30], ZnO:Ga [29] and SnO 2 :F [29,46] are used for this purpose. Additionally, the surface texture achieved on these front electrodes plays a crucial role in light management by enhancing photo-current generation and thus increasing the overall PCE [29,30,46,97].…”