Multiple-junction photoelectric device and its production process

The present invention relates to a multiple-junction photoelectric device comprising, in sequence, a substrate (4), a first conducting layer (2), at least two elementary photoelectric devices (6, 10), at least one of said elementary photoelectric devices (6) being made of microcrystalline silicon, and a second conducting layer (8). The first conducting layer (2) has a surface (2b) facing said microcrystalline silicon elementary photoelectric device such that: - said surface (2b) has a lateral feature size (D) bigger than 100 nm, and a root-means-square roughness (Rrms) bigger than 40 nm, - said surface (2b) comprises inclined elementary surfaces such that a50 is greater than 20 DEG , where aso is the angle for which 50% of the elementary surfaces of the surface of the first conducting layer (2) have an inclination equal to or less than this angle, and - said surface (2b) comprises valleys being formed between two elementary surfaces and having a radius of curvature smaller than 100 nm. Moreover, said microcrystalline silicon elementary photoelectric device (6) comprises, on the incoming light side, a p-type layer being made of at least one silicon alloy SiMx where M is O, C, N, and x> 0.1, said p-type layer containing silicon grains.