A solar cell substrate has irregularities on a surface which is in contact
with a photo-electric conversion layer, and light is incident on the side
of the irregularities. The height of the irregularities is set so that the
root mean square height is in a range of 15 nm to 600 nm, and tan .theta.
is in a range of 0.10 to 0.30, where .theta. is the angle of incline of
the surface of the irregularities with respect to an average line of the
irregularities. Light incident on the irregularities is scattered at the
interface. This increases the optical path length and thus the quantity of
light absorbed in the photo-electric conversion layer, resulting in
improved efficiency. Additionally, the photo-electric conversion layer can
be made thinner reducing deposit time and manufacturing cost. Further,
collision of crystals is not incurred, thus preventing deterioration of
photo-electric conversion efficiency which is caused by defects.
