By using a seeding technique it has been possible to reduce the thickness of p-pc-Si:H film to 230 A, with an improved electrical conductivity (0.93 S cm(-1)) and lower optical absorption compared to those of conventional p-pc-Si:H layers without a seed layer, for use at the tunnel junction and as the top layer of a double junction n-i-p structured a-Si solar cell. Undoped-muc-Si:H has been used as the seed layer. The layers were prepared by the radio frequency plasma-enhanced chemical vapour deposition (RF-PECVD) method (13.56 MHz) at 40mW/ cm(2) rf power density and low substrate temperature (200degreesC). The ultrathin seed layer (similar to30 A) enhances the growth of microcrystallinity of the p-type pc-Si:H film as confirmed by the results of transmission electron microscopy (TEM) analysis and Raman spectroscopy. (C) 2004 Elsevier B.V. All rights reserved.