The electronic properties of hydrogenated amorphous silicon (a-Si:H) relax following stretched exponentials. This phenomenon was explained in the past by dispersive hydrogen diffusion, or by retrapping included hydrogen motion. In this letter, the authors report that the electronic passivation properties of intrinsic a-Si:H /crystalline silicon (c-Si) interfaces relax following a similar law. Carrier injection dependent a-Si:Hc-Si interface recombination calculations suggest this originates from amphoteric interface state (or Si dangling bond) reduction, rather than from a field effect. These findings underline the similarity between a-Si:Hc-Si interface recombination and the electronic properties of a-Si:H bulk material. © 2008 American Institute of Physics.