Dresden 2014 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 78: Quantum dots: Preparation and characterization
HL 78.1: Talk
Wednesday, April 2, 2014, 16:30–16:45, POT 251
Nonvolatile memory characteristics of Ge nanocrystals embedded in TaZrO2 — •David Lehninger1, Peter Seidel1, Frank Schneider1, Volker Klemm2, Johannes von Borany3, and Johannes Heitmann1 — 1Institut für Angewandte Physik, TU Bergakademie Freiberg, D-09596 Freiberg — 2Institut für Werkstoffwissenschaft, TU Bergakademie Freiberg, D-09596 Freiberg — 3Institut für Ionenstrahlphysik und Materialforschung, HZDR, D-01314 Dresden
NVM devices with charge storage in discrete nanocrystals (NCs) offer the chance for better scalability and to operate at lower voltages compared to continuous floating gate (FG) flash devices. Using Ge NCs instead of Si NCs is expected to further improve the memory performance due to the smaller bandgap of Ge compared to Si.
In this work, Ge NCs embedded in a high-k control oxide have been fabricated by magnetron sputtering of Ge-TaZrO2/TaZrO2 layers on a p-type Si-Wafer covered by a 5 nm thermal oxide. The formation of spherically shaped Ge NCs in amorphous TaZrO2 is demonstrated by cross-sectional TEM. C-V measurements exhibit a counter clockwise hysteresis indicating the tunneling of holes through the SiO2 and their subsequent trapping in the Ge NCs. The memory window widens with both, sweep voltage range and programming time. The discharging kinetic is examined by the constant capacity method and shows a long time stabile state after an initial logarithmic decay. It could be shown, that MIS structures comprising Ge NCs in amorphous high-k TaZrO2 show promising NVM characteristics.