We report dependences of electrical properties on SiH4/H-2 dilution rate and film thickness for microcrystalline silicon films formed by a hydrogen radical-induced chemical vapor deposition (HRCVD) method. The electrical conductivity of the films at SiH4 18 sccm/H-2 120 seem was markedly increased to 10(-3) S/cm as film thickness increased above 100 nm. Crystalline grains with (220) orientation were formed. Theoretical analysis revealed that grain boundaries among (220) grains had a low defect density of 1 x 10(12) cm(-2) so that the high conductivity was achieved. (C) 2001 Elsevier Science B.V. All rights reserved.