Nanocrystalline silicon multilayer structures for optoelectronics

Abstract

In this paper multilayer structures, based on nanocrystalline silicon, were synthesized in order to make use of the solar spectrum more efficiently. For this purpose, silicon thin films with structure, that varies from fine- to coarse-grained in the direction from top to bottom layer, were obtained. Nanocrystalline silicon thin films were deposited by electron beam evaporation. The structure of thin film was controlled by means of deposition time and temperature. Analysis of structural studies and transmission spectra has established, that thin silicon film should be deposited at different temperatures in the order of 130, 250 and 350 oC. It has been shown, that with increasing one-layer deposition time the significant potential barrier is formed, which leads to growth of rectifying coefficient and photo-emf in multilayer structure. At the same same time, the photocurrent and short-circuit current increases with decreasing thickness of the threelayered structure. The optimal deposition time for solar cells is chosen in view of the magnitude of the filling factor, which significantly affects on the efficiency of solar energy conversion. Obtained structures can be used in photo-and UV sensors, as well as in solar cells.