Structural inhomogeneities in the form of voids of nanometer sizes (nanovoids) have long been known to be present in hydrogenated amorphous semiconductors (Si, Ge). The physical and electrical properties of hydrogenated amorphous semiconductors can be pronouncedly influenced by the presence and characteristics of such nanovoids. In this work, by measuring in situ the intrinsic stress developments during deposition of pure, amorphous and of hydrogenated amorphous semiconductor (Si, Ge) thin films, under the same conditions in ultrahigh vacuum and on a comparative basis, a major source of tensile stress development could be ascribed to the occurrence of nanovoids in a-Si:H and a-Ge:H. The measurements allowed a quantitative evaluation of the surface stress acting along the surface of the nanovoids: 1.1–1.9 N/m for a-Si:H and 0.9–1.9 N/m for a-Ge:H.
References
1.
R. A.
Street
, Hydrogenated Amorphous Silicon
(Cambridge University Press
, 1991
).2.
A.
Shah
, P.
Torres
, R.
Tscharner
, N.
Wyrsch
, and H.
Keppner
, “ Photovoltaic technology: The case for thin-film solar cells
,” Science
285
, 692
–698
(1999
).3.
W.
Fuhs
, “ Amorphous hydrogenated silicon, a-Si:H
,” in Silicon: Evolution and Future of a Technology
, edited by P.
Siffert
and E. F.
Krimmel
(Springer
, Berlin, Heidelberg
, 2004
), pp. 123
–137
.4.
J. R.
Weber
, A.
Janotti
, P.
Rinke
, and C. G.
Van de Walle
, “ Dangling-bond defects and hydrogen passivation in germanium
,” Appl. Phys. Lett.
91
, 142101
(2007
).5.
S.
Kageyama
, M.
Akagawa
, and H.
Fujiwara
, “ Dielectric function of a-Si:H based on local network structures
,” Phys. Rev. B
83
, 195205
(2011
).6.
E.
Johlin
, N.
Tabet
, S.
Castro-Galnares
, A.
Abdallah
, M. I.
Bertoni
, T.
Asafa
, J. C.
Grossman
, S.
Said
, and T.
Buonassisi
, “ Structural origins of intrinsic stress in amorphous silicon thin films
,” Phys. Rev. B
85
, 075202
(2012
).7.
Y. J.
He
, M.
Hasegawa
, R.
Lee
, S.
Berko
, D.
Adler
, and A.-L.
Jung
, “ Positron-annihilation study of voids in a-Si and a-Si:H
,” Phys. Rev. B
33
, 5924
–5927
(1986
).8.
A. H. M.
Smets
, W. M. M.
Kessels
, and M. C. M.
van de Sanden
, “ Vacancies and voids in hydrogenated amorphous silicon
,” Appl. Phys. Lett.
82
, 1547
(2003
).9.
A.
Fontcuberta i Morral
, P.
Roca i Cabarrocas
, and C.
Clerc
, “ Structure and hydrogen content of polymorphous silicon thin films studied by spectroscopic ellipsometry and nuclear measurements
,” Phys. Rev. B
69
, 125307
(2004
).10.
G. G.
Stoney
, “ The tension of metallic films deposited by electrolysis
,” Proc. R. Soc. London A
82
, 172
–175
(1909
).11.
G. E.
Jellison
and F. A.
Modine
, “ Parameterization of the optical functions of amorphous materials in the interband region
,” Appl. Phys. Lett.
69
, 371
–373
(1996
).12.
E.
Chason
and P. R.
Guduru
, “ Tutorial: Understanding residual stress in polycrystalline thin films through real-time measurements and physical models
,” J. Appl. Phys.
119
, 191101
(2016
).13.
J. A.
Floro
, P. G.
Kotula
, S. C.
Seel
, and D. J.
Srolovitz
, “ Origins of growth stresses in amorphous semiconductor thin films
,” Phys. Rev. Lett.
91
, 096101
(2003
).14.
H.
Shaik
and M.
Rao
, “ Hydrogen-induced mechanical properties of amorphous silicon thin films
,” Mater. Sci. Semicond. Process.
38
, 165
–170
(2015
).15.
A.-S.
Keita
, Z.
Wang
, F.
Phillipp
, E.
Bischoff
, and E. J.
Mittemeijer
, “ Highly retarded crystallization in hydrogenated amorphous germanium; emergence of a porous nanocrystalline structure
,” Thin Solid Films
615
, 145
–151
(2016
).16.
D. L.
Young
, P.
Stradins
, Y.
Xu
, L. M.
Gedvilas
, E.
Iwaniczko
, Y.
Yan
, H. M.
Branz
, Q.
Wang
, and D. L.
Williamson
, “ Nanostructure evolution in hydrogenated amorphous silicon during hydrogen effusion and crystallization
,” Appl. Phys. Lett.
90
, 081923
(2007
).17.
D. L.
Williamson
, “ Microstructure of amorphous and microcrystalline Si and SiGe alloys using X-rays and neutrons
,” Sol. Energy Mater. Sol. Cells
78
, 41
–84
(2003
).18.
J.
Shinar
, H.
Jia
, R.
Shinar
, Y.
Chen
, and D. L.
Williamson
, “ Microvoid, Si, H, and Al dynamics ina-Si:H/Al2O3/Al structures: A small-angle x-ray-scattering and infrared-absorption study
,” Phys. Rev. B
50
, 7358
–7364
(1994
).19.
D. L.
Williamson
, D. W. M.
Marr
, E.
Iwaniczko
, and B. P.
Nelson
, “ Small-angle neutron scattering studies of hot-wire CVD a-Si:H
,” Thin Solid Films
430
, 192
–196
(2003
).20.
J.
Melskens
, A. H. M.
Smets
, M.
Schouten
, S. W. H.
Eijt
, H.
Schut
, and M.
Zeman
, “ New Insights in the Nanostructure and Defect States of Hydrogenated Amorphous Silicon Obtained by Annealing
,” IEEE Journal of Photovoltaics
3
(1), 65
–71
(2013
).21.
M.
Fehr
, A.
Schnegg
, B.
Rech
, K.
Lips
, O.
Astakhov
, F.
Finger
, G.
Pfanner
, C.
Freysoldt
, J.
Neugebauer
, R.
Bittl
, and C.
Teutloff
, “ Combined multifrequency EPR and DFT study of dangling bonds ina-Si:H
,” Phys. Rev. B
84
, 245203
(2011
).22.
M.
Fehr
, A.
Schnegg
, B.
Rech
, O.
Astakhov
, F.
Finger
, R.
Bittl
, C.
Teutloff
, and K.
Lips
, “ Metastable defect formation at microvoids identified as a source of light-induced degradation in a-Si:H
,” Phys. Rev. Lett.
112
, 066403
(2014
).23.
J.
Melskens
, A.
Schnegg
, A.
Baldansuren
, K.
Lips
, M. P.
Plokker
, S. W. H.
Eijt
, H.
Schut
, M.
Fischer
, M.
Zeman
, and A. H. M.
Smets
, “ Structural and electrical properties of metastable defects in hydrogenated amorphous silicon
,” Phys. Rev. B
91
, 245207
(2015
).24.
Y.
Wang
, J.
Weissmüller
, and H. L.
Duan
, “ Mechanics of corrugated surfaces
,” J. Mech. Phys. Solids
58
, 1552
–1566
(2010
).25.
S.
Hara
, S.
Izumi
, T.
Kumagai
, and S.
Sakai
, “ Surface energy, stress and structure of well-relaxed amorphous silicon: A combination approach of ab initio and classical molecular dynamics
,” Surf. Sci.
585
, 17
–24
(2005
).26.
P. H.
Keck
and W.
Van Horn
, “ The surface tension of liquid silicon and germanium
,” Phys. Rev.
91
, 512
–513
(1953
).27.
N.
Eustathopoulos
and B.
Drevet
, “ Surface tension of liquid silicon: High or low value?
,” J. Cryst. Growth
371
, 77
–83
(2013
).© 2017 Author(s).
2017
Author(s)
You do not currently have access to this content.