Photoinduced Amorphous ↔ Crystalline Transitions In Sb_X Se_1−X Films

Abstract

We present a study of laser pulse induced crystallization and amorphization in Sb_xSe_1−x films. The time required to reach stable amorphous state after the pulse increases with exciting pulse length and becomes constant when stationary temperature field is approached by the end of the pulse. The time dependence of the excited spot’s local temperature is deduced directly from amorphization threshold intensity dependence on the pulse length and is used to calculate the cooling times after the amorphizing pulse. Two photocrystallization regimes are distinguished depending on whether the melting starts before or after the end of crystallization, the condition depending on crystallization tendency for given composition x. The occurrence of melting limits the maximum optical contrast during photocrystallization. The results show that the crystallization tendency of Sb_xSe_1−x rises with x and has a local maximum between x = 0.5 and x = 0.7.