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Characterization of thin film produced by quantum dot deposition process
~ Pergamon
J . Autnol Sci .• Vol. 27. 5uppl. I. pp. 5149-5150. 1996 Copy right 0 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0021·g502/96 SI5 .00 + 0.00
PH: SOO21-8502(96)OO147-4
CHARACfERIZATION OF THIN FILM PRODUCED BY QUANTUM DOT DEPOSITION PROCESS Shigeo AONO, Masayuki ITOH and Hiroshi T AKANO Department of Chemical Engineering and Materials Science Faculty of Engineering, Doshisha University Tanabe, Kyoto 61 ()-D3, Japan and Susumu TOHNO Institute of Atomic Energy, Kyoto University Uji, Kyoto 611, JAPAN
KEYWORDS Quantum Dot Deposition; Thin Film; Nann-phase Particles; Aerosol Process In the previous work on the non-crystalline structure of nano-phase particles (M.ltoh et al. , 1996), we pointed out a possibility of the new and efficient process for thin film production hy mutual fusion of the particles (quantum dots) due to the quantum size effect following their direct deposition onto a substrate. Thereupon, the synthesis method and characterizations of the thin film produced hy the new process, i.e., Quantum Dot Deposition (QDD) process were discussed in the present report. The concept of synthesis process of QDD and the outline of experimental system were illustrated in Fig.I. The thin film was formed on a substrate of Si(lll) in helium gas at low pressure (133 Pal with nann-phase silver particles produced by the modified gas evaporation method (S .Tohno et al., 1996); the geometric mean diameter and the geometric standard deviation of the particles were about 3.5 nm and lA, respectively. Characteristics of the thin film were determined by a transmission electron microscopy (TEM). a reflection high-energy electron diffraction (RHEED) and a X-ray diffraction for thin film (XRD). Fig .2 by TEM showed typical stages of the formation process of a thin film for several elapsed times. (a) simple deposition of particles on the substrate (30 min), (h) growing of islands hy mutual fusion of the deposited particles (60 min) , (c) connection of the island and formation of a thin film having clear crystalline structure (120 min) . , I
Vacuum chamber Drying column
..
'
Illustration of Nanophase Particles Flux
Valve
Vacuum gauge
MBP RP Fig.I Outline of experimental system and concept of QDD process SI49
SISO
Abstracts of the 1996 European Aerosol Conference
(a)
( /)
50nm
50nm
II " II Fig.2
TEM images of formation process of silver film. (Deposition time;(a)30 min. (b)60 min and (c)120 min. Thin film formed on a carbon micro grid)
Because of the transmittance of electron into Si(111) substrate. the thin films for TEM were formed not on Si(1l1) but on a carbon micro grid, Therefore, the inner and surface structures of the film on Si(lll) were observed with XRD and RHEED. The XRD chart in Fig.3 showed that the thin film formed on Si(lll) had a good crystalline structure and preferred rU1J texture of silver crystal. The clear ring pattern by RHEED at the upper right-side in Fig.3 also indicated that the silver thin film on Si(11!) had a polycrystalline structure near the surface. Though there remains several problems to be solved for a practical use of thi~ process. the present results made it clear that a crystallized thin film was surely formed by such fusion due to their quantum size effect following direct deposition of nano-phase particles. The ODD process is very effective to any other synthesis processes using aerosol process because the transportation of mass hy particles is much larger than that of atomic vapor. The ODD process is not a chemical process hut a pure physical process and will be more gentle nano-technology to global environment.
oa N
0;
-c
20
30
40
50
60
70
80
_Old g .)
Fig.3 XRD chart and RHEED pattern of silver thin film on Si(1ll) formed with 120 min by ODD.
REFERENCES M.Itoh. S.Tohno, M.Adachi and K.Kimura, (1996) EXAFS Study on non~Tystallinc structure of binary component (BiCu, BiTe) nann-phase particles. Surf. Rev. and Leurs, 3, No.1 . S.Tolmo, M.ltoh, S.Aono and H.Takano, (1996) Production of conracr-trce nanoparticles by aerosol process: Dependence of particle size on gas pressure,.l. Colloid. Interface Sci. (in press).
J . Autnol Sci .• Vol. 27. 5uppl. I. pp. 5149-5150. 1996 Copy right 0 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0021·g502/96 SI5 .00 + 0.00
PH: SOO21-8502(96)OO147-4
CHARACfERIZATION OF THIN FILM PRODUCED BY QUANTUM DOT DEPOSITION PROCESS Shigeo AONO, Masayuki ITOH and Hiroshi T AKANO Department of Chemical Engineering and Materials Science Faculty of Engineering, Doshisha University Tanabe, Kyoto 61 ()-D3, Japan and Susumu TOHNO Institute of Atomic Energy, Kyoto University Uji, Kyoto 611, JAPAN
KEYWORDS Quantum Dot Deposition; Thin Film; Nann-phase Particles; Aerosol Process In the previous work on the non-crystalline structure of nano-phase particles (M.ltoh et al. , 1996), we pointed out a possibility of the new and efficient process for thin film production hy mutual fusion of the particles (quantum dots) due to the quantum size effect following their direct deposition onto a substrate. Thereupon, the synthesis method and characterizations of the thin film produced hy the new process, i.e., Quantum Dot Deposition (QDD) process were discussed in the present report. The concept of synthesis process of QDD and the outline of experimental system were illustrated in Fig.I. The thin film was formed on a substrate of Si(lll) in helium gas at low pressure (133 Pal with nann-phase silver particles produced by the modified gas evaporation method (S .Tohno et al., 1996); the geometric mean diameter and the geometric standard deviation of the particles were about 3.5 nm and lA, respectively. Characteristics of the thin film were determined by a transmission electron microscopy (TEM). a reflection high-energy electron diffraction (RHEED) and a X-ray diffraction for thin film (XRD). Fig .2 by TEM showed typical stages of the formation process of a thin film for several elapsed times. (a) simple deposition of particles on the substrate (30 min), (h) growing of islands hy mutual fusion of the deposited particles (60 min) , (c) connection of the island and formation of a thin film having clear crystalline structure (120 min) . , I
Vacuum chamber Drying column
..
'
Illustration of Nanophase Particles Flux
Valve
Vacuum gauge
MBP RP Fig.I Outline of experimental system and concept of QDD process SI49
SISO
Abstracts of the 1996 European Aerosol Conference
(a)
( /)
50nm
50nm
II " II Fig.2
TEM images of formation process of silver film. (Deposition time;(a)30 min. (b)60 min and (c)120 min. Thin film formed on a carbon micro grid)
Because of the transmittance of electron into Si(111) substrate. the thin films for TEM were formed not on Si(1l1) but on a carbon micro grid, Therefore, the inner and surface structures of the film on Si(lll) were observed with XRD and RHEED. The XRD chart in Fig.3 showed that the thin film formed on Si(lll) had a good crystalline structure and preferred rU1J texture of silver crystal. The clear ring pattern by RHEED at the upper right-side in Fig.3 also indicated that the silver thin film on Si(11!) had a polycrystalline structure near the surface. Though there remains several problems to be solved for a practical use of thi~ process. the present results made it clear that a crystallized thin film was surely formed by such fusion due to their quantum size effect following direct deposition of nano-phase particles. The ODD process is very effective to any other synthesis processes using aerosol process because the transportation of mass hy particles is much larger than that of atomic vapor. The ODD process is not a chemical process hut a pure physical process and will be more gentle nano-technology to global environment.
oa N
0;
-c
20
30
40
50
60
70
80
_Old g .)
Fig.3 XRD chart and RHEED pattern of silver thin film on Si(1ll) formed with 120 min by ODD.
REFERENCES M.Itoh. S.Tohno, M.Adachi and K.Kimura, (1996) EXAFS Study on non~Tystallinc structure of binary component (BiCu, BiTe) nann-phase particles. Surf. Rev. and Leurs, 3, No.1 . S.Tolmo, M.ltoh, S.Aono and H.Takano, (1996) Production of conracr-trce nanoparticles by aerosol process: Dependence of particle size on gas pressure,.l. Colloid. Interface Sci. (in press).