Effects of Bi on crystallisation in Ge–Sb–Te–Bi

Abstract

Blue light optical storage products will become the next generation devices for recording media in the near future. To increase the crystallisation speed of recording by 405 nm wavelength blue laser diode, bismuth (Bi) is applied to substitute small quantities of antimony (Sb) in a pseudobinary GeTe–Sb₂Te₃ (GeSb₂Te₄) alloy material. It is shown that the activation energies for crystallisation of Ge–Sb–Te–Bi are reduced by addition of Bi indicating the improvement of recording speed. The Ge–Sb–Te–Bi material is incorporated into actual blue light phase change optical disks and is found to provide good land and groove recording characteristics, cross-talk characteristics, and cross-erase characteristics. It is demonstrated a promising candidate for HD DVD-RAM applications.