Articles you may be interested inOn the structural-optical properties of Al-containing amorphous Si thin films and the metal-induced crystallization phenomenon Amorphous Si:Sb alloy thin films with various Sb concentrations were deposited on preoxidized Si substrates in an electron-beam evaporation system. The optical properties and the crystallization of the amorphous alloy as a function of Sb concentration were investigated with spectroscopic ellipsometry and x-ray diffraction (XRD), respectively. It has been found that the optical energy band gap decreases from 1.6 to 0.35 eV with increasing Sb concentration from 0 to 50 at. %, and that the index of refraction decreases overall with the increase of Sb concentration. From the crystallization study, it is seen that the crystallization temperature of the alloy decreases with increasing Sb concentration. From a detailed XRD examination, three different crystallization products from the amorphous alloys have been observed in low, medium, and high Sb concentration regions. The structure of the amorphous alloys and the correlation between the optical properties and the structures of the amorphous alloys are discussed. It is suggested that the amorphous alloys have differing favorable bonding structures, depending on the Sb concentration, that correspond to the bonding structures of the crystallization products.

Thermal stability and crystallization of amorphous Si:P alloy thin films consisting of 20–44 at. % P have been studied in this work. The results show that the alloys have crystallization temperatures ranging from 850 to 1150 °C, which are all higher than that of pure amorphous Si, and that the variation of resistivity of the alloys during the 120 h aging at 300 °C is small (0.6%). These results indicate that the alloys have a high thermal stability, which is in agreement with the thermodynamic prediction we have made. It has also been observed that the crystallization products for these alloys are different. A new silicon phosphide phase has been observed in the 30 at. % alloy sample and suggested to be possibly a hexagonal Si7P3 phase which has lattice parameters a=5.32 Å and c=13.3 Å. The alloy films were deposited onto quartz substrates and Si wafers by coevaporation of Si and P. X-ray diffractometry and transmission electron microscopy were utilized to investigate the crystallization temperature and product of the amorphous alloys.