[Show abstract][Hide abstract] ABSTRACT: Transient processes of Ge/Si hetero-nanocrystal floating gate memories are simulated numerically. Compared with Si nanocrystal memories, Ge/Si hetero-nanocrystal memories show similar writing and erasing efficiency with a weaker writing saturation and markedly improved retention characteristics.
[Show abstract][Hide abstract] ABSTRACT: The Ge/Si hetero-nanocrystal as a floating gate has been discussed and improved. The charge stored in the quantum well formed by SiO<sub>2</sub>-Ge-Si has to be thermally activated to the valence band of the Si nanocrystal before it can leak to the substrate which significantly reduces the leakage current from the charge storage node (nanocrystal) to the substrate. The simulation shows that the flash memory with Ge-Si (3 nm/3 nm) hetero-nanocrystal floating gates possesses a retention time of about ten years with a tunneling oxide of only 2 nm. Both writing and erasing speeds are fast in the Ge-Si hetero-nanocrystal memories, which is similar to that in the memory based on Si nanocrystals only.
IEEE Transactions on Nanotechnology 02/2006; · 1.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The titanium silicide/silicon (TiSi2/Si) heteronanocrystals are fabricated on SiO2 thin films. The metal-oxide-semiconductor structure embedding the TiSi2/Si heteronanocrystals shows superior performance over the Si dot device. The charge loss rate in the TiSi2/Si heteronanocrystal device is 7.5 times less than that of the Si dot device. It is also found that the TiSi2/Si heteronanocrystal device has wider memory window than the Si dot counterpart.
[Show abstract][Hide abstract] ABSTRACT: After the proposal of nanocrystal floating gate memory by Tiwari, tremendous effort has been made to improve the device performance of a memory containing nanocrystal floating gate, including semiconductor nanocrystals (Si, Ge et al.), metal dot (W, Ni, Au, Pt, Ag et al.), dielectric nanocrystals (Al<sub>2</sub>O<sub>3</sub>, HfO<sub>2</sub> and Si<sub>4</sub>N<sub>3</sub> et al.) and Ge/Si hetero-nanocrystals. In this work, we will report for the first time titanium silicide/Si hetero-nanocrystal floating gate memory
Device Research Conference Digest, 2005. DRC '05. 63rd; 02/2005
[Show abstract][Hide abstract] ABSTRACT: A nanocrystal memory using CoSi 2 /Si hetero-nanocrystals as floating gate was proposed. Numerical investigations on the writing, erasing and retention were performed. The hetero-structure provides an extra quantum well for the charge to achieve much longer reten-tion time while maintains a writing/erasing speed similar to that of Si nanocrystal memory.
[Show abstract][Hide abstract] ABSTRACT: The transient process of the programming and erasing is very important for a nanocrystal-floating-gate flash memory. In this work, a computer simulation was carried out to investigate the charging, retention and erasing processes of our proposed Ge/Si hetero-nanocrystal floating gate flash memory. The transient gate current, the transient drain current and the average charge in one dot were simulated respectively. Evident hysteresis features can be observed in the transient processes in a voltage-sweeping measurement mode. While measuring the transient process in a constant voltage mode, the time decay of transient current and charge are weakened if Ge is used on the Si dot, indicating a longer retention time for Ge/Si-floating-gate flash memory.