The Investigation Of M/Si-NPA’s Electrical Characteristics

The research of the metal/porous silicon nanocomposites is one of the popular subjects inmetal/silicon nanocomposites. The electrical characteristics of the metal/silicon nanoporouspillar array composites have more advantages than that of metal material and porous siliconnanocomposites. The metal/silicon-based nanocomposites could be widely used in themanufacturing of the functional materials for such as photovoltaic conversion，rectificationby their excellent electrical characteristics.In this paper, Au/Si-NPA(species A: made by fresh substrates, species B: made by agedsubstrates) and Cu/Si-NPA(species C: made by fresh substrates, species D: made by agedsubstrates) samples were made by immersion method on substrate of silicon nanoporous pillararray (Si-NPA), their electrical characteristics were tested and analyzed separately, and theresults achieved are as followed:1. It was investigated by testing and analyzing their I-V characteristics that the depositiontime-dependent electrical characteristics of Au/Si-NPA samples obtained in differentdeposition time. The result showed that the one-way electric conductivity of the Au/Si-NPAsamples demotrated in the I-V characteristic curve decreased as the deposition time increasedwhen the deposition time was shorter than30minutes; but it increased as the deposition timeincreased when the deposition time was longer than30minutes. This is mainly because theselectivity of the gold’s position when it was deposited on the Si-NPA and the substrateoxidation characteristics during the gold’s deposition, these made the samples’ surfacemorphology and composition changed as the different deposition time and caused thedifferences of the samples’ electrical characteristics.2. The samples’ electrical characteristics influenced by the substrates’ storage time wereinvestigated. The results indicated that the positive current of the samples of species A waslarge than that of species B. This phenomenon firstly was caused by the different surfacemorphology of the two types samples, the gold particles were deposited uniformly andcompactly on the surface of the samples, so it’s easy for current transfer, however the goldparticles of species B were deposited uniform and compact on the bottom of the sample’ssurface as well, but there is almost no gold particles on the silicon pillar, this disrupted currenttransfer. Secondly, the aged substrates were oxidized more than the fresh substrates after aperiod of time,which led to the positive current of samples of species B decreased more thanthat of species A. 3. The deposition time-dependent I-V curve of Cu/Si-NPA samples were investigated, andfound that the Cu/Si-NPA samples showed an I-V characteristic curve as the I-V curve ofnormal conductors, and the current decreased as the deposition time increased at the same biasvoltage. This was mainly caused by the unique physical and chemical properties of copper.when the deposition time was shorter than30minutes, the ability of the samples thataccelerates the current’s transfe by deoxidize copper is weaker than the ability of disruptingcurrent’s transfe by the substrates’ oxidation, and this made the current decreased.4. Under the same applied voltage, the current of species D was smaller than that of species Cdue to the characteristics of substrates’ oxidation. After a period of time, the SiO2on thesubstrate surface generated by oxidation obstructed the deoxidation of the copper andhindered the current transfer.