Nanopipes associated to screw dislocations are studied by transmission electron microscopy in Si -doped GaN films grown on silicon substrates. The observations revealed that dislocations had an empty core and that an AIN interlayer is suited to block their propagation. The termination mechanism is discussed in terms of strain and kinetic growth factors, which may affect the creation and propagation of nano pipes. According to the observations, it is proposed that either step pinning or lateral overgrowth occurring at the proximity of the defect assists in capping the nanopipe. (C) 2016 Elsevier B.V. All rights reserved.