Enhanced vertical photo-sensitivity in mu c-Si : H/a-Si : H superlattices

The microcrystalline silicon/amorphous silicon (mu c-Si:H/a-Si:H) superlatt ice showed an enhanced vertical,photo- sensitivity (photo-conductivity/dark -conductivity), whereas it reserved a lateral photo-sensitivity nearly unch anged. The film was fabricated by alternating the mixing of SiH4 and HZ in a photo-chemical vapor deposition system. The fact that a high vertical pho to-sensitivity and an obvious crystalline volume fraction can be obtained a t the same time distinguishes the mu c-Si:H/a-Si:H superlattice from the bu lk mu c-Si:H. The change of the vertical dark-conductivity with the sublaye r thickness was explained by the change of the a-Si:PI sublayer's electrica l conduction property. We think that the thin a-Si:H sublayers play an impo rtant role of perturbing a columnar structure of the mu c-Si:H. (C) 2000 El sevier Science B.V. All rights reserved.