Nonvolatile floating gate memory containing AgInSbTe–SiO₂nanocomposite layer and capping the HfO₂/SiO₂composite blocking oxide layer

Abstract

An extremely large memory window shift of about 30.7 V and high charge storage density =2.3 × 10(13) cm(-2) at ± 23 V gate voltage sweep were achieved in the nonvolatile floating gate memory (NFGM) device containing the AgInSbTe (AIST)-SiO(2) nanocomposite as the charge trap layer and HfO(2)/SiO(2) as the blocking oxide layer. Due to the deep trap sites formed by high-density AIST nanocrystals (NCs) in the nanocomposite matrix and the high-barrier-height feature of the composite blocking oxide layer, a good retention property of the device with a charge loss of about 16.1% at ± 15 V gate voltage stress for 10(4) s at the test temperature of 85 °C was observed. In addition to inhibiting the Hf diffusion into the programming layer, incorporation of the SiO(2) layer prepared by plasma-enhanced chemical vapor deposition in the sample provided a good Coulomb blockade effect and allowed significant charge storage in AIST NCs. Analytical results demonstrated the feasibility of an AIST-SiO(2) nanocomposite layer in memory device fabrication with a simplified processing method and post-annealing at a comparatively low temperature of 400 °C in comparison with previous NC-based NFGM studies.

Multilevel characteristics and memory mechanisms for nonvolatile memory devices based on CuInS2 quantum dot-polymethylmethacrylate nanocomposites

“…8,9 The potential applications of nano floating gate memory (NFGM) devices fabricated utilizing hybrid nanocomposites have led to substantial research efforts to form various nanocomposites that act as charge-storage regions. 10,11 Among the various kinds of nanocomposites, CuInS 2 (CIS) QDs with environmentfriendly properties are considered as perspective alternatives to intrinsically toxic QDs containing Cd, Se, Hg, and Pb atoms. 10,12 Even though some studies concerning the memory effects of the NFGM devices fabricated utilizing various QDs embedded in an organic layer have been conducted due to their relatively simple fabrication and inexpensive production processes, [13][14][15] very few investigations on the capacitance characteristics and the memory mechanisms for multilevel nonvolatile memory devices based on CIS QDs embedded in a polymethylmethacrylate (PMMA) layer have been reported.…”

“…10,11 Among the various kinds of nanocomposites, CuInS 2 (CIS) QDs with environmentfriendly properties are considered as perspective alternatives to intrinsically toxic QDs containing Cd, Se, Hg, and Pb atoms. 10,12 Even though some studies concerning the memory effects of the NFGM devices fabricated utilizing various QDs embedded in an organic layer have been conducted due to their relatively simple fabrication and inexpensive production processes, [13][14][15] very few investigations on the capacitance characteristics and the memory mechanisms for multilevel nonvolatile memory devices based on CIS QDs embedded in a polymethylmethacrylate (PMMA) layer have been reported. This letter reports data for the capacitance characteristics and the memory mechanisms for multilevel nonvolatile memory devices fabricated utilizing CIS QDs embedded in a PMMA layer.…”