Memory Functions of Cadmium Sulfide Embedded Zr-Doped HfO₂High-k Dielectrics

Abstract

Nonvolatile memory characteristics of CdS embedded Zr-doped HfO 2 high-k MOS capacitors have been studied. The n-type nature of the CdS caused the preference of hole-trapping in the bulk high-k layer. The lack of frequency dispersion of the capacitance-voltage curve was due to the passivation of defects at the CdS/high-k interface. The hole trapping/detrapping mechanism was verified with the current-voltage measurement. The loosely trapped holes were quickly released upon the release of the stress voltage. The embedded CdS layer maintained the hole trapping capability after the dielectric breakdown. About half of the originally trapped charges were retained after releasing the stress voltage for 10 years. The CdS embedded samples showed good memory and charge retention characteristics. Therefore, the CdS embedded Zr-doped HfO 2 gate dielectric structure is suitable for low voltage nonvolatile memory applications.