Reversibility and stability of tellurium alloys for optical data storage applications

We demonstrate for the first time that Te87Ge8Sn 5 films, which are amorphous as deposited, can be optically switched between the crystalline and amorphous states more than 106 times. The measured reflectivity changed from 40% to 60% and the transmission changed from 3% to 1.5%, respectively, between the amorphous and crystalline states. The crystallization temperature of the cycled spots is ≊75°C and these spots are observable after >20 weeks. It is found that the crystallization temperature of cycled spots is typically about 20°C lower than that of the unwritten film. Increasing the Ge concentration leads to increased crystallization temperature and increased minimum crystallization time without affecting reversibility.