Influence of Hot Carrier Diffusion on the Density Limitation of Optical Data Storage

Abstract

Hot carrier diffusion (HCD) in Ge-Sb-Te phase change materials for re-writable optical data storage applications may limit the resolution of blue laser recording and cause additional cross-talk. As simulation studies show, the high optical excitation energy and small optical focus size characteristic of blue laser data storage formats lead to significant hot carrier diffusion prior to the energy transfer to the crystal lattice. As a consequence, the optical energy is deposited in an area larger than the laser spot size, leading to enhanced intertrack cross-talk and thermal cross-erase that reduces the quality of high-density optical storage. Therefore, the fundamental limit of resolution for re-writable optical storage systems is no longer determined by the laser focus size alone, but also by additional nonequilibrium HCD effects.