Interfacial Polar‐Bonding‐Induced Multifunctionality of Nano‐Silicon in Mesoporous Silica

2011

J. Phys. Chem. B

Self Cite

A liquid crystal polymer (LCP) self-assembled on a photoirradiated substrate can modify the viscoelastic response of liquid crystal medium on the substrate. Sum-frequency vibrational spectroscopy shows that the phenyl groups of LCP are oriented epitaxially with layer thickness and an in-plane alignment order much higher than that at the photoirradiated surface can be yielded. The liquid crystal molecules confined between the LCP-coated substrates reveals a stronger correlation among the thermally excited fluctuation modes. Our finding can be used to tailor the boundary forces on alignment substrates and to optimize the device performance.

Section: T H Imentioning

confidence: 99%

Self Assembled Liquid Crystal Polymers on Photo-Irradiated Alignment Surfaces for Tailoring Response Properties of Liquid Crystal Molecules

2011

J. Phys. Chem. B

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“…We thereafter synthesized Si nanocrystals in the MS templates with the high-density inductively coupled plasma method. 8 By invoking an enhancement effect with an electrically biased substrate similar to the gap-filling/etching process used in IC manufacturing, we can create one-side bonded silicon nanocrystals with polar layer structures at the interfaces of nc-Si and MS as illustrated in Fig. 1͑a͒.…”

mentioning

confidence: 99%

“…We calculated that a relative displacement of the charge distributions across the interfacial layers of nc-Si/MS, which have a thickness of about 3-4 Å, can readily produce an electric polarization as large as 5 C / cm 2 . 8 Schematic drawings are presented in the inset of Fig. 2͑a͒ to facilitate the illustration of the switching process.…”

mentioning

confidence: 99%

Nonvolatile memory with switching interfacial polar structures of nano Si-in-mesoporous silica

Shieh

Applied Physics Letters

et al. 2009

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We show an artificially engineered electret with Si nanocrystals embedded in mesoporous silica for nonvolatile memory. We attribute the polarization to from polar layers lying at the interfaces between one-side bonded Si nanocrystals and mesoporous silica matrix. Under external field, the Si nanocrystals could be displaced in the porechannels causing displaced charge distributions and therefore a field-controllable electric polarization. Nonvolatile memory is demonstrated with a metal-oxide-semiconductor field-effect transistor.To satisfy the ever-increasing need for information flow and storage, the industry of semiconductor integrated circuits ͑ICs͒ has eagerly hunted for an ideal semiconductor memory technology with the high speed of static random access memory ͑RAM͒, the nonvolatility of flash, and the density of dynamic RAM. 1 Nonvolatile memories ͑NVMs͒ can retain the data even when power is interrupted and are becoming a crucial component for the society of efficient energy utilization. In this regard, NVM based on the concept of storing information into the states of electric polarization had attracted much interest. In a ferroelectric field effect transistor with the gate dielectric layer being replaced by a ferroelectric thin film, 2-4 the electric polarization of the gate can be sensed by monitoring the magnitude of the source-drain current, 2-4 offering high speed random access, 5 low power consumption, 2,4,5 and nonvolatility. 1 The spontaneous polarization of a ferroelectric crystal with a noncentrosymmetric structure is mainly due to permanent dipoles that can switch directions under an action of electric field. 6 Bulk silicon does not possess ferroelectric properties due to the diamond structure with centrosymmetry. To realize ferroelectric RAMs ͑FeRAM͒, tremendous efforts have been made to integrate nonsilicon-based ferroelectric films, such as lead zirconate titanate ͑PZT͒ and strontium bismuth tantalite ͑SBT͒, 2,6 with the mature silicon memory technology. However, the interface reactions between PZT ͑SBT͒ and the Si substrate often generate mobile ions and lead to low data retention time. 2,3,7 Recently, we had shown that interfacial properties could be employed to yield multifunctionality 8 with polar Si-O nanostructures formed by asymmetrically embedding Si nanocrystals ͑nc-Si͒ in mesoporous silica ͑MS͒. In this letter, a full silicon-based metal-oxide-semiconductor field-effect transistor ͑MOSFET͒ NVM was demonstrated by using the artificially engineered electret. 9 Figure 1͑a͒ presents the schematic of the NVM cell, where the electret film is sandwiched between two oxide buffer layers to serve as the gate dielectrics.We prepared the test samples of nc-Si/MS by first depositing a 10-nm-thick SiO 2 buffer layer and then spin coating a 90-nm-thick MS nanotemplate layer on n-or p-type silicon. We thereafter synthesized Si nanocrystals in the MS templates with the high-density inductively coupled plasma method. 8 By invoking an enhancement effect with an electrically biased substrate similar ...

“…15 Green nanosecond laser, with high repetition rate and long wavelength, is particularly suitable for non-melt LSA because of its sub-millisecond scanning, low-photo-energy light producing less damage on metal-gate, gate dielectric, or even more delicate nanostructured gate stacks. [16][17][18] In this study, we take advantages of thin tunneling oxide, in situ Si-QD-embedded nitride layer, and selective source/ drain (S/D) activation by green nanosecond laser spike annealing (GN-LSA) that is enabled by metal-gate as a lightblocking layer. The laser activated Si-QD NVM shows microsecond P/E speed under low operating voltage and reveals high performance in reliability of retention and endurance in comparison with conventional metal-…”

mentioning

confidence: 99%

Fast programming metal-gate Si quantum dot nonvolatile memory using green nanosecond laser spike annealing

Lien

Shieh

Applied Physics Letters

et al. 2012

The ultrafast metal-gate silicon quantum-dot (Si-QD) nonvolatile memory (NVM) with program/ erase speed of 1 ls under low operating voltages of 6 7 V is achieved by thin tunneling oxide, in situ Si-QD-embedded dielectrics, and metal gate. Selective source/drain activation by green nanosecond laser spike annealing, due to metal-gate as light-blocking layer, responds to low thermal damage on gate structures and, therefore, suppresses re-crystallization/deformation/ diffusion of embedded Si-QDs. Accordingly, it greatly sustains efficient charge trapping/de-trapping in numerous deep charge-trapping sites in discrete Si-QDs. Such a gate nanostructure also ensures excellent endurance and retention in the microsecond-operation Si-QD NVM. V