Sub-micron thin films of polycrystalline silicon obtained by low-press
ure chemical vapor deposition, boron-implanted (amount varying from 10
(12) to 10(16) cm(-2)), and annealed at 760 degrees C for 26 h under a
n oxygen ambient (dry O-2) have been characterized in terms of structu
ral and electrical properties. The results obtained are correlated fir
st with the Wall-effect measurements, which gives the resistivity rho,
the concentration of the free carriers p and the mobility mu, and in
the second part with the observations of transmission electron microsc
opy (TEM), which gives the size of grains. The variations of rho, p an
d mu have been studied as a function of the dopant concentration. A lo
w rate of activation has been measured (40%) and a very low value of t
he mobility mu has been noted (3 cm(2) V-1 s(-1)) as well as small gra
in size. These results have been discussed both qualitatively and quan
titatively, based on the existence of phenomena of carrier trapping an
d dopant segregation at the grain boundaries.