a-Si:H crystallization from isothermal annealing and its dependence on the substrate used

Abstract

We present hydrogenated amorphous silicon ( a-Si:H) films which were deposited on two different sub­ strates (glass and mono-crystalline silicon) after an isothermal annealing treatment at 250"( for up to 14 h.The annealed amorphous films were analyzed using atomic force microscopy, Raman and FfiR spec­ troscopy. Films deposited on glass substrate experienced an amorphous-crystalline phase transition after annealing because of the metal-induced crystallization effect, reaching approximately 70% conversion after 14 h of annealing. An absorption frequency of the TO-phonon mode that varies systematically with the substoichiometry of the silicon oxide in the 1046-1170 cm-1 region was observed, revealing the reac­ tivity of the film with the annealing time. For similar annealing time, films deposited on mono-crystalline silicon substrate remained mainly amorphous with minimal Si-crystalline formation. Therefore. the crys­ talline formations and the shape of the films surfaces depends on the annealing time as well as on the substrate employed during the deposition process of the a-Si:H film.