나노 복합체를 사용한 고용량 비휘발성 기억소자에 차단층 삽입을 통한 성능 향상

Abstract

Nonvolatile memory devices based on hybrid organic and inorganic nanocomposites have been receiving attention due to their low-power consumption, low cost, and flexibility. Because fullerenes are well-known class of n-type organic semiconductors with a rather high electron mobility, they have used for organic electronic devices. Even though some studies concerning the memory effects of organic bistable devices (OBDs) fabricated utilizing fullerenes have been performed, investigations about the enhancement of the memory margin for OBDs fabricated utilizing C60 embedded in a polymethyl methacylate (PMMA) matrix due to an inserted blocking layer have not been performed yet. This paper reports data for the enhancement of the memory margin for OBDs fabricated utilizing C60 embedded in a PMMA layer. The OBDs used in this study were Al/C60 nanoparticles embedded in PMMA layer/indium-tin-oxide (ITO) coated-glass substrates. The C60 in the OBDs acts as an electron transport layer. The nanocomposites of C60 embedded in a PMMA layer, acting as a charge storage region in OBDs, were formed by using a 3wt% of the PMMA solution with a 0.15 wt% of the C60 nanoparticles. The solutions containing of the PMMA and the C60 nanoparticles were deposited on the ITO coated-glass substrates by using a spin-coating technique. The baking process was conducted for 30 min to remove the residual solvent. Then, a top Al electrode with a thickness of 150 nm was thermally evaporated on the C60/PMMA nanocomposites. Prior to the formation of the C60/PMMA nanocomposites, the blocking layer was inserted between C60 nanoparticles embedded in a PMMA layer and ITO glass. Current-voltage (I-V) curves for the Al/C60 nanoparticles embedded in PMMA layer/ITO and Al/C60 nanoparticles embedded in PMMA layer/blocking layer/ITO devices showed an electrical hysteresis behavior, which is an essential feature for a bistable device. The ON/OFF ratio of the OBDs with a blocking layer was larger than that without a blocking layer. The enhancement origin of the memory margin for OBDs fabricated utilizing C60 nanoparticles embedded in a PMMA matrix due to an inserted blocking layer is described on the basis of the I-V results.