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Proceedings Paper

Self-assembling formation of Si-based quantum dots and control of their electric charged states for multi-valued memories
Author(s): Seiichi Miyazaki
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Paper Abstract

We have prepared hemispherical Si nanocrystals as quantum dots (QDs) on thermally-grown SiO2 layers in a self-assembled manner by controlling the early stages of LPCVD using SiH4, and also formed Si-QDs with a Ge core by controlling the selective growth conditions in SiH4- and GeH4-LPCVD. From the change in the surface potential at each of QDs caused by electron injection or emission through ultrathin SiO2 as measured with an AMF/Kelvin probe technique, we have quantified how many electrons or holes can be retained stably in the single dot covered with ultrathin SiO2 at room temperature without any external biases. We have found that, for Si-QDs with a Ge core, electrons are retained stably in Si clad while holes in Ge core. MOS capacitors and FETs with the Si dots as a floating gate have also been designed and fabricated. Multiple-step electron charging (or discharging) characteristics of the Si-dot floating gate are observable presumably because columbic force arising from charged dots efficiently suppresses the electron charging of neighboring neutral dots. From the temperature dependence of temporal change in the drain current at a fixed positive gate bias after complete discharging of the Si-QDs floating gate, we were found that the multiple step charging proceeds with an thermal activation energy being almost equal to the energy separation in the sum of quantized and charging energies between the charged states.

Paper Details

Date Published: 22 November 2005
PDF: 8 pages
Proc. SPIE 6002, Nanofabrication: Technologies, Devices, and Applications II, 60020K (22 November 2005); doi: 10.1117/12.632483
Show Author Affiliations
Seiichi Miyazaki, Hiroshima Univ. (Japan)

Published in SPIE Proceedings Vol. 6002:
Nanofabrication: Technologies, Devices, and Applications II
Warren Y.-C. Lai; Leonidas E. Ocola; Stanley Pau, Editor(s)

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