High-density assembly of nanocrystalline silicon quantum dots

Abstract

This paper reports on a new bottom-up technique of forming silicon nanostructures based on assembly of nanocrystalline (nc) Si dots from the solution. The nc-Si dots with a diameter of 8 ± 1 nm were fabricated by using VHF plasma decomposition of pulsed SiH 4 gas supply and deposited on the substrate randomly. We first studied the method of making the nc-Si dot dispersion solution by immersing the deposited wafer into various kinds of solvent with ultra sonic treatment. We found that methanol works as a suitable solvent for nc-Si dots. We then add a drop of the nc-Si dot solution onto other substrates and evaporated it. During the evaporation the nc-Si dots were assembled in the solution via the lateral capillary meniscus force which works as an attractive force between the dots. Use of SiO 2 substrate with good surface wettability with the solution was found vital to have the maximum meniscus force and to have two-dimensional assembly of the dots. The evaporation speed was carefully controlled via temperature and evaporation pressure to achieve high dot density assembly. In addition, we examined the assembly of the nc-Si dots on the silicon-on-insulator substrates with various kinds of nanoscale patterning and succeeded in making the nc-Si dots cluster bridging between the nanoelectrodes with a gap of as small as 20 nm.

Origin of photoluminescence in nanocrystalline Si:H films

“…6 is similar to the location of the red and green regions reported by Zhao et al [61], and Edelberg et al [62]. On the basis of these results, we suggest that the 1.7-1.75-eV-PL spectra to be due to quantum confinement [1,9,16,17,20,22,36,37] [65], in good agreement with the present work. It is noted that the PL spectra from this nc-Si:H were broad, and that as the nanocrystal size was reduced, PL broadening accompanied PL blue shift.…”

“…In particular, since the discovery of efficient visible light photoluminescence (PL) in porous Si (PS) [4] in 1990, a lot of work has been done in studying Si nanostructures [5][6][7][8], Si nanocrystals produced with several different techniques (namely, co-sputtering [9], ion implantation [10], ion beam sputtering [11], HF sputtering [12], RF sputtering [13], RF magnetron sputtering [14,15], pulsad laser deposition [16], low-pressure chemical vapor deposition (LPCVD) [17], plasma-enhanced (PE) CVD [18][19][20], low energy PECVD [21] and VHF plasma decomposition of pulsed SiH 4 gas supply [22]). The PECVD technique appears to be a promising deposition method for large-area thin film technology and has been employed for industrial applications [23].…”

Hybrid numerical analysis of a high-speed non-volatile suspended gate silicon nanodot memory (SGSNM)

“…In order to avoid this leakage issue, an alternative FG structure which adopts silicon nanodots (SiNDs) rather than a solid polysilicon was proposed [5,6]. The SiNDs are single crystals surrounded by a thin SiO 2 isolation layer [7,8]. In case of a leakage path formation within the tunnel oxide layer, only the electrons stored adjacent to the path might leak and as consequence the total loss of charge stored in the FG is expected to decrease.…”

Integration of Tunnel-Coupled Double Nanocrystalline Silicon Quantum Dots with a Multiple-Gate Single-Electron Transistor

“…Integration of nc-Si QDs with patterned substrate has been carried out by atomic force microscope (AFM) or dots solution techniques. 8,9) But position control for all dots using AFM technique is laborious work. The nc-Si QDs assembly technique has recently been applied for the pre-patterned nanostructures, but position control of individual nc-Si QDs is not realized yet.…”