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

Abstract

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 ...

Electrical characterisation of Si‐SiO2 structures

“…The reason is their promising application in nonvolatile memories [1], third generation solar cells [2] and single-electron devices [3]. These structures have predominantly been studied by structural and optical characterization techniques, such as transmission electron microscopy (TEM), infrared absorption spectroscopy (IR) and photoluminescence (PL).…”

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

“…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-…”