Two-dimensional (2D) slab photonic crystals based on Er-doped hydrogenated amorphous silicon alloyed with carbon (a-Si:H:C) are proposed and realized. Freestanding and oxide-cladding slab structures are fabricated and compared. 2D slab active photonic crystal structures show enhanced extraction of the trivalent erbium ion (Er3+) luminescence independent of the pump intensity. Temperature-insensitive light extraction efficiency with negligible surface-related nonradiative recombination was experimentally observed. The maximum enhancement became eightfold in freestanding slab structures. (C) 2003 American Institute of Physics.