Ge nanocrystals embedded in Hf-aluminate high-k: Gate dielectric for floating gate memory application

P. F. Lee, W. L. Liu, Z. T. Song, Jiyan Dai

Research output: Journal article publicationConference articleAcademic researchpeer-review


Recently, many efforts have been made to improve the device performance of nanocrystal memory by replacing the SiO2with various high dielectric constant (high-k) materials, especially embedded with Ge nanocrystals. This paper demonstrates the floating gate memory effect by embedding nanometer-sized Ge nanocrystals in hafnium aluminate (HfAlO) high-fe gate dielectric. A 5 nm-thick amorphous thin film of HfAlO was first deposited on (100) p-Si substrates as a tunneling gate oxide layer by laser molecular beam epitaxy deposition using a HfO2and A12O3composite target. Well-defined (∼10 nm in diameter) nanometer-sized Ge dots were subsequently deposited on this thin tunneling gate oxide followed by a 30 nm-thick top control gate oxide of HfAlO. Transmission electron microscopy has been carried out for a detailed study of structural properties of the Ge nanocrystals embedded in the HfAlO films, and their relationships to electrical properties. Electrical properties have been characterized by means of high-frequency capacitance-voltage (C-V) and current-voltage (I-V) measurements on the metal-oxide-semiconductor capacitors. A counter-clockwise hysteresis C-V loop has been obtained and a threshold voltage shift of 1.0 V has been achieved indicating stored electrons (up to a density of 2×1012cm-2) in the Ge-nanodots floating gate and thus the memory effect. Time-dependent I-V measurement also showed low leakage current of floating gate system. These results suggest that the Ge nanocrystals embedded in HfAlO are promising for floating gate memory device application.
Original languageEnglish
Article number63
Pages (from-to)150-155
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 20 Jun 2005
EventMicro- and Nanotechnology: Materials, Processes, Packaging, and Systems II - Sydney, Australia
Duration: 13 Dec 200415 Dec 2004


  • Floating gate memory
  • Ge nanocrystals
  • HfAlO
  • High-k dielectrics

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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