A possible explanation for this is that thick layers form large Ga particles (400 nm in diameter in average for 100-nm thick Ga layer) sitting at the top of the wires which stay in a molten form at high temperatures. Therefore, the molten form of Ga slides down, covering the surface of the wire creating smaller catalyst sites for growth of thinner nano-wires from the original nano-wire surface. Figure 3 shows SEM images of SiNWs grown at 200°C from the same thicknesses of Ga layers. It can be seen from the picture that at this temperature, nano-wire growth takes place also from 7.5-nm Ga layer, and there are no more tree-like structures formed
from thicker layers. Figure 3 SiNWs grown at 200°C from (a) 100, (b) 40 and (c) 7.5nm Ga catalyst layers. The scale bar is1 μm. When the this website growth temperature was decreased down to 150°C, it can be seen from Figure 4 that only smaller catalyst particles initiate the nano-wire growth. There is no nano-wire growth observed from larger particles formed in 100-nm Ga layer (Figure 4a), but only nano-wires grown from between the big particles, possibly from smaller Ga sites that have been left at the surface of the substrate. It can be seen from Figure 4c that there are densely grown nano-wires initiated from the 7.5-nm thick Ga layer. Nano-wire growth was also LY3009104 solubility dmso observed from 40-nm Ga layer (Figure 4b). Figure 4 SiNWs grown at 150°C from (a) 100, (b) 40 and (c) 7.5nm Ga catalyst
layers. The scale bar is 1 μm. One of the possible explanations for the abovementioned dependence of the catalyst layer/growth temperature can be the following: (a) thinner layers at high temperatures get etched away by hydrogen plasma introduced for surface pre-treatment, therefore resulting in the absence of nano-wires for these Reverse transcriptase samples, (b) thicker layers create particles of larger size which at low temperatures do not reach the Si solubility level sufficient to absorb enough Si to result in supersaturation and consequent precipitation of SiNWs, whereas the smaller particles
require less Si for supersaturation, therefore result in nano-wire growth. Overall, it can be concluded that in order to grow thin diameter nano-wires using thin catalyst layers (under 10 nm), lower growth temperatures should be used, whereas thick nano-wire and tree-like nano-structure growth require thick catalyst layer and high growth temperature. Bistable memory device characteristics The structure of the bistable memory device fabricated in this work with SiNWs as the charge storage medium is demonstrated in Figure 5. In order to study the effect of the SiNWs in memory devices, two samples were SCH727965 prepared: one with SiNWs grown from Ga catalyst and the other without Ga layer referred as reference sample. Both substrates, one coated with thin layer of Ga and the other without Ga thin layer (reference sample), were placed in the PECVD chamber.