Growth Behavior of Ge Quantum Dots on the Nano-sized Si(111) surface bounded by the (100) facets
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Growth Behavior of Ge Quantum Dots on the Nano-sized Si(111) surface bounded by the (100) facets S.-S. Ferng and S.-S. Ferng and D.-S. Lin D.-S. Lin Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan The strain-driven self-organized growth o f three-dimensional quantum-dot (QD) nanos tructure in semiconductor heteroepitaxy ha s attracted much attention . Nanoscale-sized surface in the form of me sa or ridges on patterned substrates offer opportunities not only for novel growth-co ntrol engineering, but also fundamental un derstanding of the size-dependent crystal growth phenomena during the formation of Q Ds. . The studies of the Ge QD growth on the windows or mesas have been largely conducted on the (100) plane of silicon. Few literatures discussed the effect of the Ge growth on the nano-sized (111) Introduction Method Microscopy: Commercial AFM operated in the tapping mode. Sample Prepared: Results Conclusions References 100 sec 20 sec Ge dots on (100) planes: derivative AFM image The formation of well-confined (111) surfaces Ge dots on (111) planes 20 sec 100 sec Anisotropic etching: 20% KOH + IPA (5:1) at room temperature UHVCVD: 650℃, 20 and 100 sec Ge 2 H 4 5 sccm P hotoresist P R coating 100nm SiO 2 E x posure- D evelopm e nt & SiO etchin g 2 P R strip & S i etchin g in K O H solu tion Rem ove S iO & HF dip 2 S i(100)substrate 2D arrays of 3×6 μm 2 rectangular mesas and 1×1 μm 2 negative pyramid. 5 μm× 5 μm 5.5 μm× 5.5 μm Etching depth= 120 nm 300 nm 500 nm Etching depth= 80 nm 150 nm 420 nm 970 nm The Ge dots on the (100) plane average radius average height 20 sec 28 nm 10.6 nm 100 sec 30 nm 15.2 nm 0 20 40 60 80 100 120 140 160 0 10 20 30 40 50 60 D epth (nm ) A ngle (deg) (111) (114) (113) Ge dot Profiles and slop angles of Si mesa sidewall vs. etching depth the (111) facets become well- defined as the etching depth is larger than 80 nm. (111) (100) (100) 0 20 40 60 80 100 120 140 160 -160 -140 -120 -100 -80 -60 -40 -20 0 Lateraldistance (nm ) (111) Z height(nm ) (100) 54.7 ¢X The w idth of(111)plane (nm ) 0 200 400 600 800 1000 1200 Volum ne (x10 3 nm 3 ) 0 10 20 30 40 50 0 2 4 6 8 10 12 14 16 Thickness (M L) triangle:thickness colorbar:volume W 111 = 150 nm W 111 = 370 nm W 111 = 100 nm W 111 = 610 nm W 111 = 180 nm W 111 = 530 nm W 111 = 1190 nm 400 nm× 400 nm Nuclei-free bands (the denuded zone ) clearly observed on both edge of the (111) facets, as an example marked in blue dash line. The boundaries between (111) and (100) planes : denuded zone The boundaries between (111) facets: denuded zone The volumes distribution and the thickness of Ge on the (111) planes with different width. (100) (100) (111) (111) (100) (100) The effective chemical potential for Ge adatoms on the (111) facet is smaller than that on the (100) facet, leading to the effective adatom flux from (111) to (100). (100) (100) (111) μ 100 ＜ μ 111 Acknowledgements Tsung-Hsi YANG Microelectronics and Information Systems Research Center, National Chiao Tung University, Hsinchu 300, Taiwan Guangli LUO National Nano Device Laboratories, No. 26, Prosperity Road 1, Science-base Industrial Park, Taiwan 300, R.O.C. A. Bruce, Joyce, et al.: Quantum Dots: Fundamentals, Applications, and Frontiers, NATO science series. 190 (Springer, Dordrecht, 2005) and reference therein. This paper is published at Nanotechnology 17, 5207 ( 2006) as a front cover page featured article .
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(111). (113). (114). Growth Behavior of Ge Quantum Dots on the Nano-sized Si(111) surface bounded by the (100) facets. S.-S. Ferng and D.-S. Lin Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan. - PowerPoint PPT Presentation
Transcript of Growth Behavior of Ge Quantum Dots on the Nano-sized Si(111) surface bounded by the (100) facets
Growth Behavior of Ge Quantum Dots on the Nano-
sized Si(111) surface bounded by the (100) facets S.-S. Ferng and S.-S. Ferng and D.-S. Lin D.-S. Lin Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan
The strain-driven self-organized growth of three-dimensional quantum-dot (QD) nanostructure in semiconductor heteroepitaxy has attracted much attention .
Nanoscale-sized surface in the form of mesa or ridges on patterned substrates offer opportunities not only for novel growth-control engineering, but also fundamental understanding of the size-dependent crystal growth phenomena during the formation of QDs. .
The studies of the Ge QD growth on the windows or mesas have been largely conducted on the (100) plane of silicon. Few literatures discussed the effect of the Ge growth on the nano-sized (111) plane.
Introduction Method
Microscopy: Commercial AFM operated in the tapping mode.
Sample Prepared:
Results
Conclusions
References
100 sec
20 sec
Ge dots on (100) planes: derivative AFM image The formation of well-confined (111) surfaces
Ge dots on (111) planes
20 sec 100 sec
Anisotropic etching: 20% KOH + IPA (5:1) at room temperatureUHVCVD: 650 , 20 and 100 sec ℃
Ge2H4
5 sccm
Photoresis t
PR coating
100 nm SiO2
Ex posure-Dev elopme nt
& SiO etc hin g2
PR str ip&
S i etc hin g in K OH solu tion
Remove S iO&
HF dip
2
Si(100) substrate
2D arrays of 3×6 μm2 rectangular mesas and 1×1 μm2 negative pyramid.
5 μm× 5 μm
5.5 μm× 5.5 μm
Etching depth= 120 nm 300 nm 500 nm
Etching depth= 80 nm 150 nm 420 nm 970 nm
The Ge dots on the (100) plane
average radius average height
20 sec 28 nm 10.6 nm
100 sec 30 nm 15.2 nm
0 20 40 60 80 100 120 140 1600
10
20
30
40
50
60
Depth (nm)
An
gle
(d
eg)
(111)
(114)
(113)
Ge dot
Profiles and slop angles of Si mesa sidewall vs. etching depth
the (111) facets become well-defined as the etching depth is larger than 80 nm.
(111)(100)
(100)
0 20 40 60 80 100 120 140 160
-160
-140
-120
-100
-80
-60
-40
-20
0
Lateral distance (nm)
(111)
Z h
eig
ht
(nm
)
(100) 54.7 ¢X
The width of (111) plane (nm)
0 200 400 600 800 1000 1200
Vo
lum
ne
(x10
3 n
m3 )
0
10
20
30
40
50
0
2
4
6
8
10
12
14
16
Th
ickness (M
L)
triangle: thickness
color bar: volume
W111= 150 nm
W111= 370 nm
W111= 100 nm
W111= 610 nm
W111= 180 nm
W111= 530 nm
W111= 1190 nm
400 nm× 400 nm
Nuclei-free bands (the denuded zone ) clearly observed on both edge of the (111) facets, as an example marked in blue dash line.
The boundaries between (111) and (100) planes :denuded zoneThe boundaries between (111) facets: denuded zone
The volumes distribution and the thickness of Ge on the (111) planes with different width.
(100) (100)
(111)
(111)
(100)
(100)
The effective chemical potential for Ge adatoms on the (111) facet is smaller than that on the (100) facet, leading to the effective adatom flux from (111) to (100).
(100)
(100)
(111
)
μ100 ＜ μ111
AcknowledgementsTsung-Hsi YANGMicroelectronics and Information Systems Research Center, National Chiao Tung University, Hsinchu 300, TaiwanGuangli LUONational Nano Device Laboratories, No. 26, Prosperity Road 1, Science-base Industrial Park, Taiwan 300, R.O.C.
A. Bruce, Joyce, et al.: Quantum Dots: Fundamentals, Applications, and Frontiers,NATO science series. 190 (Springer, Dordrecht, 2005) and reference therein.
This paper is published at Nanotechnology 17, 5207 ( 2006) as a front cover page featured article.
