AVS 51st International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP14
Observation of Standing Waves in Si(111)@sr@3x@sr@3-Ag Islands at Room Temperature

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: T. Ishizuka, Tokyo Institute of Technology, Japan
Authors: T. Ishizuka, Tokyo Institute of Technology, Japan
H. Hirayama, Tokyo Institute of Technology, Japan
Correspondent: Click to Email
It is widely accepted that Si(111)@sr@3x@sr@3-Ag surface has S1 surface state with a free electron like dispersion. The free-electron like surface dispersion has been confirmed by observing standing wave patterns at the @sr@3x@sr@3-Ag domain boundaries in STM at 5K [1]. In this study, we demonstrated that the free-electron like @sr@3x@sr@3-Ag surfaces can be utilized as the template for the nano-sized quantum structure construction. We obtained nano-scale @sr@3x@sr@3-Ag islands by depositing sub monolayer Ag on the Si(111)7x7 substrate surfaces at 770K. The standing wave patterns of electrons confined in the nano-islands were observed by a STM-based dI/dV mapping at 70K and room temperature. In the dI/dV images, the standing wave patterns were observed in the inside of the @sr@3x@sr@3-Ag islands of the size below 20nm. We found that the patterns persisted even at room temperature in the islands of 10nm scale. Then, we calculated the standing wave patterns numerically by solving Schrodinger equation for some islands with complex shapes using Finite Element Method(FEM). The numerical results reproduced characteristics of the observed standing wave patterns successfully, though the coincidence was not perfect. Furthermore, we fabricated point defects on @sr@3x@sr@3 Ag island artificially by using STM tip, and observed the resultant change of standing wave pattern. These results indicated that the 10nm scale islands still worked as Quantum Wells(QWs) even at room temperature. The shape of the islands could be modified by the STM tip induced atom manipulation. The confined electronic states are numerically predictable. These are preliminary demonstrations of the artificial design and fabrication of nano-sized QWs workable at room temperature on the template of the @sr@3x@sr@3-Ag surfaces.[1]N.Sato and S.Takeda PRB.59.3.2035(1999).