The coefficient of thermal expansion (CTE), biaxial modulus, and stress of
some amorphous semiconductors (a-Si:H, a-C:H, a-Ge:H, and a-GeCx:H) and met
allic (Ag and Al) thin films were studied. The thermal expansion and the bi
axial modulus were measured by the thermally induced bending technique. The
stress of the metallic films, deposited by thermal evaporation (Ag and Al)
, is tensile, while that of the amorphous films deposited by sputtering (a-
Si:H, a-Ge:H, and a-GeCx:H) and by glow discharge (a-C:H) is compressive. W
e observed that the coefficient of thermal expansion of the tetrahedral amo
rphous thin films prepared in this work, as well as that of the films repor
ted in literature, depend on the network strain. The CTE of tensile films i
s smaller than that of their corresponding crystalline semiconductors, but
it is higher for compressive films. On the other hand, we found out that th
e elastic biaxial modulus of the amorphous and metallic films is systematic
ally smaller than that of their crystalline counterparts. This behavior sta
nds for other films reported in the literature that were prepared by differ
ent techniques and deposition conditions. These differences were attributed
to the reduction of the coordination number and to the presence of defects
, such as voids and dangling bonds, in amorphous films. On the other hand,
columnar structure and microcrystallinity account for the reduced elasticit
y of the metallic films. (C) 1999 American Institute of Physics. [S0021- 89
79(99)01021-X].