Abstract

Present research in phase change optical recording is focused on further improving the performance of optical discs based mostly on GeSbTe compound films. Additionally, GeSbTe has recently become a key material for promising electrically addressed storage devices compatible with CMOS technology. Ge₂Sb₂Te₅ is considered the standard composition for a fast phase change material since both amorphization and crystallization can be triggered with laser pulses as short as 10 ns. However, using femtosecond laser pulses only amorphization has been reported so far,¹ due to the difficulty for stable crystalline nuclei to form and grow under the strong supercooling achieved. The dynamics of the phase change is of prime importance for improving device performance. The aim of this work is to study the amorphization dynamics upon pulsed laser irradiation (ns and fs) with highest temporal resolution (ns and fs). The pump laser used was a femtosecond-seeded regeneratively amplified laser system operating at 800 nm central wavelength with a pulse duration that could be switched from 120 fs to 8 ns by blocking the seed laser. The reflectivity evolution was measured in real-time with ns resolution² by focusing a cw probe laser at 532 mil onto the center of the region irradiated by the pump laser and measuring the reflection with a fast photodiode.

© 2007 IEEE