| Co-Investigator(Kenkyū-buntansha) |
ETO Mikio Keio University, Faculty of Science and Technology, Assistant Professor, 理工学部, 助教授 (00221812)
KURODA Tadahiro Keio University, Faculty of Science and Technology, Professor, 理工学部, 教授 (50327681)
KUWANO Hiroshi Keio University, Faculty of Science and Technology, Professor, 理工学部, 教授 (10051525)
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| Research Abstract |
In Si-based quantum computer, ^<31>P should be distributed in an array at a distance of about 20 nm in spin-free silicon (spin zero ^<28>Si or ^<30>Si) as a qubit. In the present work, in order to fabricate its basic device structure, we aim to perform the experiments on the epitaxial growth of isotopically controlled silicon layers and the transformation of ^<30>Si to ^<31>P by neutron irradiation. This method for distributing ^<31>P in Si is superior to the ion-implantation technique, which is inherently random to the depth. For this purpose, first, epitaxial growth technique of almost 100% ^<30>Si was developed by the gas source MBE method using enriched ^<30>SiH_4, which was purchased from Kurchatov laboratory, Russia. Thus this spin-free Si epitaxial layer can be available to the base for Si-based quantum computer. Using this technique, we succeeded to fabricate the natural Si/^<30>Si/natural Si (^<28>Si:^<29>Si:^<30>Si=92.2:4.7:3.1) isotope double hetero-structures by supplying alternately normal SiH_4 and enriched ^<30>SiH_4. Then, neutron irradiation was carried out to transform ^<30>Si to ^<31>P at Japan Atomic Energy Research Institute with thermal neutron flux of 1×10^<14> cm^<-2> s^<-1> for 16 h. By the precise secondary ion mass spectroscopy (CAMECA-SIMS) measurement, the formation of ^<31>P from ^<30>Si was confirmed. Its concentration was to be about 5×10^<16> cm^<-3>w, which was almost equal to the theoretically predicted value. If the neutron irradiation is performed to the ^<29>Si/^<30>Si/^<29>Si double hetero-structures, nuclear spin ^<31>P will be distributed in a spin-free silicon (^<31>Si ), which will be used as a basic structure of Si-based quantum computer.
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