2005 Fiscal Year Final Research Report Summary
The fabrication of super atom structure using Si based self-assembled quantum dots and its electron state control
| Project/Area Number |
15206035
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
MIYAZAKI Seiichi Hiroshima University, graduate school of advanced sciences of matter, professor, 大学院・先端物質科学研究科, 教授 (70190759)
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| Co-Investigator(Kenkyū-buntansha) |
HIGASHI Seiichiro Hiroshima University, graduate school of advanced sciences of matter, associate professor, 大学院・先端物質科学研究科, 助教授 (30363047)
MURAKAMI Hideki Hiroshima University, graduate school of advanced sciences of matter, research associate, 大学院・先端物質科学研究科, 助手 (70314739)
KOHNO Atsushi Fukuoka University, department of science, associate professor, 理学部, 助教授 (30284160)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Quantum dots |
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| Research Abstract |
We have demonstrate that the Si nucleation density with remote H_2 plasma treatments just before SiH_4-LPCVD can be controlled up to 〜1x10^<11>cm^<-2> by changing the VHF power, the H_2 plasma pressure and the substrate temperature. The combination of the remote Ar plasma and subsequent H_2 plasma is quite effective to achieve a uniform size distribution of Si dots with an areal density of the order of 10^<11>cm^<-2>. This technique is very promising for the fabrication of multiple stacked structures of Si-based dots embedded in Si0_2.
The combination of LPCVD and remote plasma surface treatments including remote plasma oxidation is a promising method to fabricate multiply-stacked structures consisting of Si-QDs and ultrathin SiO_2 interlayers. From observing the. charging and discharging characteristics of multiply-stacked Si-QDs in Si0_2. The temporal decay of charged states of high density Si-QDs can be characterized by not only discharging process through the bottom tunnel oxide but
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also the neutralization due to carrier recombination.
For valency control of self-assembled Si quantum dots (Si-QDs), boron or phosphorous doping to Si-QDs was performed by a pulse injection of 1% B_2H_6 or PH_3 diluted with He during the dot formation on thermally-grown Si0_2 from thermal decomposition of pure SiH_4. Electron charging to and discharging from B or P-doped Si-QDs were studied to characterize their electronic charged states by a Kelvin probe technique using Rh-coated AFM tip. The potential changes corresponding to the extraction of one electron from the B and P-doped Si-QDs were observed by applying tip biases of +0.5V and +0.2V, respectively. On the other hand, for pure Si-QDs with almost the same size as doped Si-QDs, the tip bias causing almost the same amount of the potential change was as high as 〜1V. The electron extraction from B and P-doped Si-QDs can be interpreted in terms of the emission of an electron generated from ionized B acceptor and of a conduction electron caused by ionized P donor, being different from the emission of valence electrons from undoped Si-QDs. Also, an improvement of retention characteristics of positively-charged states was confirmed especially for P-doped Si-QDs. Less
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