Silicon Nanocrystal Flash Memory

Newly Synthesized Silicon Quantum Dot–Polystyrene Nanocomposite Having Thermally Robust Positive Charge Trapping

“…Since the first report by Tiwari demonstrating the use of silicon nanocrystals to replace the polysilicon floating gate in nonvolatile memory devices, many other materials have been tested. − Among the nanocrystal-based memory devices, silicon nanocrystals embedded in SiO 2 have received much interest due to the perfect interface between the silicon nanocrystals and SiO 2 . The oxide matrix acts as a potential barrier that confines trapped charges within the individual silicon nanocrystals, thus reducing the charge loss due to interparticle tunneling or to leakage to the channel or gates .…”

“…Therefore, not only the nanocrystals, themselves, but also the insulating matrix and their interface quality are of importance to the device performance. Much of the effort to fabricate silicon nanocrystals embedded in an oxide insulating matrix has incorporated synthetic procedures that require either high temperatures and/or ultra high vacuum conditions, all of which are inappropriate for large scale processes or organic based electronics applications. , Several solution processes have been successfully established to fabricate memory devices in which pre-prepared or in-situ grown metal or semiconductor nanocrystals are embedded in a large bandgap polymer. ,− Striving to adopt these methods to fabricate silicon nanocrystal based nanocomposites, however, remains a big challenge, probably due to the difficulty in preparing stable colloidal silicon nanocrystals . Additionally, the surface chemistry of colloidal silicon nanocrystals needs to be similar with that of the polymer host matrix in order to avoid the aggregation of nanocrystals during device fabrications. , …”

Direct Evaluation of the Quantum Confinement Effect in Single Isolated Ge Nanocrystals

“…The most notable physical property of semiconductor nanocrystals (NCs) is the quantum confinement (QC) effect, which manifests itself by the widening of the fundamental band gap of the material upon decreasing NC size . The wide-ranging interest in these quantum-confined systems relates to the special mesoscopic physics that governs their properties as well as the various associated possible electronic , and optoelectronic , applications. Of the many NC–semiconductor systems that have been investigated in the context of QC, group-IV elements are among the most widely studied. , From a fundamental viewpoint, interest in this class of materials arises mainly because the indirect band gaps of Si and Ge preclude a straightforward understanding of the observed relatively strong photoluminescence arising from associated NCs .…”