TY - JOUR
T1 - Influence of Ge nanocrystals and radiation defects on C-V characteristics in Si-MOS structures
AU - Levy, Shai
AU - Shlimak, Issai
AU - Chelly, Avraham
AU - Zalevsky, Zeev
AU - Lu, Tiecheng
PY - 2009/12/15
Y1 - 2009/12/15
N2 - Metal-oxide-semiconductor (MOS) structures containing 74Ge nanocrystals (NC-Ge) imbedded inside the SiO2 layer were studied for their capacitance characterization. Ge atoms were introduced by implantation of 74Ge+ ions with energy of 150 keV into relatively thick (∼640 nm) amorphous SiO2 films. The experimental characterization included room temperature measurements of capacitance-voltage (C-V) dependences at high frequencies (100 kHz and 1 MHz). Four groups of MOS structures have been studied: The 1st-"Initial" samples, without Ge atoms (before ion implantation). The 2nd-"implanted" samples, after Ge+ ion implantation but before annealing, with randomly distributed Ge atoms within the struggle layer. The 3rd-samples after formation of Ge nanocrystals by means of annealing at 800 °C ("NC-Ge" samples), and the 4th-"final" samples: NC-Ge samples that were subjected by an intensive neutron irradiation in a research nuclear reactor with the integral dose up to 1020 neutrons/cm2 followed by the annealing of radiation damage. It is shown that in "initial" samples, the C-V characteristics have a step-like form or "S-shape", which is typical for MOS structures in the case of high frequency. However, in "implanted" and "NC-Ge" samples, C-V characteristics have "U-shape" despite the high frequency operation. In addition, "NC-Ge" samples exhibit a large hysteresis which may indicate charge trapping at the NC-Ge. Combination of the "U-shape" and hysteresis characteristics allows us to suggest a novel 4-digits memory retention unit. "Final" samples indicate destruction of the observed peculiarities of C-V characteristics and recurrence to the C-V curve of "initial" samples.
AB - Metal-oxide-semiconductor (MOS) structures containing 74Ge nanocrystals (NC-Ge) imbedded inside the SiO2 layer were studied for their capacitance characterization. Ge atoms were introduced by implantation of 74Ge+ ions with energy of 150 keV into relatively thick (∼640 nm) amorphous SiO2 films. The experimental characterization included room temperature measurements of capacitance-voltage (C-V) dependences at high frequencies (100 kHz and 1 MHz). Four groups of MOS structures have been studied: The 1st-"Initial" samples, without Ge atoms (before ion implantation). The 2nd-"implanted" samples, after Ge+ ion implantation but before annealing, with randomly distributed Ge atoms within the struggle layer. The 3rd-samples after formation of Ge nanocrystals by means of annealing at 800 °C ("NC-Ge" samples), and the 4th-"final" samples: NC-Ge samples that were subjected by an intensive neutron irradiation in a research nuclear reactor with the integral dose up to 1020 neutrons/cm2 followed by the annealing of radiation damage. It is shown that in "initial" samples, the C-V characteristics have a step-like form or "S-shape", which is typical for MOS structures in the case of high frequency. However, in "implanted" and "NC-Ge" samples, C-V characteristics have "U-shape" despite the high frequency operation. In addition, "NC-Ge" samples exhibit a large hysteresis which may indicate charge trapping at the NC-Ge. Combination of the "U-shape" and hysteresis characteristics allows us to suggest a novel 4-digits memory retention unit. "Final" samples indicate destruction of the observed peculiarities of C-V characteristics and recurrence to the C-V curve of "initial" samples.
KW - C-V characteristics
KW - Isotopically enriched Ge nanocrystals
KW - MOS structures
KW - Neutron-transmutation doping
UR - http://www.scopus.com/inward/record.url?scp=74349119050&partnerID=8YFLogxK
U2 - 10.1016/j.physb.2009.08.303
DO - 10.1016/j.physb.2009.08.303
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AN - SCOPUS:74349119050
SN - 0921-4526
VL - 404
SP - 5189
EP - 5191
JO - Physica B: Condensed Matter
JF - Physica B: Condensed Matter
IS - 23-24
ER -