Fabrication of gold nanoparticles using low hydrothermal reaction for memory applicatio
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Date
2016-02-01
Authors
Ng Soo Ai
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Abstract
Formation of well distributed Gold nanoparticles (AuNPs) on memory devices is the main issue upon facing scaling down dilemma. AuNPs were successfully grown on the templated silicon (Si) and indium tin oxide (ITO) glass substrates using a low temperature hydrothermal method. In this work, Aluminum (Al) or Zinc (Zn) templates were deposited on the Si substrates, while Al template was deposited on the ITO glass substrate. Al and Zn template have been selected as the template due to defined grain boundaries can be obtained for sites on formation of AuNPs. The effect of annealing temperature of templates, hydrothermal reaction duration (1-5 h), HAuCl4 concentration (0.001-0.020 M), Al(NO3)3 concentration (0.01-0.20 M), Zn(NO3)2 concentration (0.01-0.20 M) on the formation of AuNPs were investigated. The optimum result obtained on Si substrate was the face centered cubic (FCC) AuNPs formed on the non annealed sputtered Al template which consisted of 80 ± 4 nm and 42 ± 7 nm particle size with 1.29 x 1012 and 2.71 x 1012m−2 area density for large and small AuNPs, respectively. The sample exhibited the lowest threshold voltage (Vth) of 2.2 V in I-V analysis and 284 charges stored per AuNP in C-V analysis. The conduction mechanisms of AuNPs embedded in organic layers involved Thermionic emission (TE), Schottky and Poole Frenkel emission in low voltage region. In medium voltage region, trapped charge limited current (TCLC) happened while spaced charge limited current (SCLC) occurred in high voltage region. In terms of transparent memory devices, good distribution of FCC structure AuNPs with 135 ± 28 nm (1.30 x 1012 m-2) and 89 ± 11 nm (3.47 x 1012 m-2) for large and small particle sizes and area density produced charge storage capability of 0.8 V turn “ON” voltage and 74 charges stored per AuNP for the memory device on ITO glass substrate. These findings proved that discrete distribution in combination with large and small AuNPs contributed to excellent memory effects due to enlargement of surface area properties.