Browsing by Subject "Nonvolatile memory devices"

Now showing 1 - 4 of 4

Open Access
Charge Trapping Memory with 2.85-nm Si-Nanoparticles Embedded in HfO2
(ECS, 2015-05) El-Atab, N.; Turgut, Berk Berkan; Okyay, Ali Kemal; Nayfeh, A.
In this work, the effect of embedding 2.85-nm Si-nanoparticles charge trapping layer in between double layers of high-κ Al2O3/HfO2 oxides is studied. Using high frequency (1 MHz) C-Vgate measurements, the memory showed a large memory window at low program/erase voltages due to the charging of the Si-nanoparticles. The analysis of the C-V characteristics shows that mixed charges are being stored in the Si-nanoparticles where electrons get stored during the program operation while holes dominate in the Si-nanoparticles during the erase operation. Moreover, the retention characteristic of the memory is studied by measuring the memory hysteresis in time. The obtained retention characteristic (35.5% charge loss in 10 years) is due to the large conduction and valence band offsets between the Si-nanoparticles and the Al2O3/HfO2 tunnel oxide. The results show that band engineering is essential in future low-power non-volatile memory devices. In addition, the results show that Si-nanoparticles are promising in memory applications.
Open Access
Cubic-phase zirconia nano-island growth using atomic layer deposition and application in low-power charge-trapping nonvolatile-memory devices
(Institute of Physics Publishing Ltd., 2017) El-Atab, N.; Ulusoy, T. G.; Ghobadi, A.; Suh, J.; Islam, R.; Okyay, Ali Kemal; Saraswat, K.; Nayfeh, A.
The manipulation of matter at the nanoscale enables the generation of properties in a material that would otherwise be challenging or impossible to realize in the bulk state. Here, we demonstrate growth of zirconia nano-islands using atomic layer deposition on different substrate terminations. Transmission electron microscopy and Raman measurements indicate that the nano-islands consist of nano-crystallites of the cubic-crystalline phase, which results in a higher dielectric constant (κ ∼ 35) than the amorphous phase case (κ ∼ 20). X-ray photoelectron spectroscopy measurements show that a deep quantum well is formed in the Al2O3/ZrO2/Al2O3 system, which is substantially different to that in the bulk state of zirconia and is more favorable for memory application. Finally, a memory device with a ZrO2 nano-island charge-trapping layer is fabricated, and a wide memory window of 4.5 V is obtained at a low programming voltage of 5 V due to the large dielectric constant of the islands in addition to excellent endurance and retention characteristics.
Open Access
Graphene Nanoplatelets Embedded in HfO2 for MOS Memory
(Electrochemical Society Inc., 2015) El-Atab, N.; Turgut, Berk Berkan; Okyay, Ali Kemal; Nayfeh, A.
In this work, a MOS memory with graphene nanoplatelets charge trapping layer and a double layer high-κ Al2O3/HfO2 tunnel oxide is demonstrated. Using C-Vgate measurements, the memory showed a large memory window at low program/erase voltages. The analysis of the C-V characteristics shows that electrons are being stored in the graphene-nanoplatelets during the program operation. In addition, the retention characteristic of the memory is studied by plotting the hysteresis measurement vs. time. The measured excellent retention characteristic (28.8% charge loss in 10 years) is due to the large electron affinity of the graphene. The analysis of the plot of the energy band diagram of the MOS structure further proves its good retention characteristic. Finally, the results show that such graphene nanoplatelets are promising in future low-power non-volatile memory devices.
Open Access
Memory effect by charging of ultra‐small 2‐nm laser‐synthesized solution processable Si‐nanoparticles embedded in Si–Al2O3–SiO2 structure
(Wiley-VCH Verlag, 2015) El-Atab, N.; Rizk, A.; Tekcan, B.; Alkis, S.; Okyay, Ali Kemal; Nayfeh, A.
A memory structure containing ultra-small 2-nm laser-synthesized silicon nanoparticles is demonstrated. The Si-nanoparticles are embedded between an atomic layer deposited high-κ dielectric Al2O3 layer and a sputtered SiO2 layer. A memory effect due to charging of the Si nanoparticles is observed using high frequency C-V measurements. The shift of the threshold voltage obtained from the hysteresis measurements is around 3.3V at 10/-10V gate voltage sweeping. The analysis of the energy band diagram of the memory structure and the negative shift of the programmed C-V curve indicate that holes are tunneling from p-type Si via Fowler-Nordheim tunneling and are being trapped in the Si nanoparticles. In addition, the structures show good endurance characteristic (>105program/erase cycles) and long retention time (>10 years), which make them promising for applications in non-volatile memory devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.