In this letter, we examine the feasibility of applying positron annihilation spectroscopy to the study of hydrogenized amorphous silicon(a-Si:H)-based structures produced by chemical vapor deposition techniques. The positron probe, sensitive to open volume formations, is used to characterize neutral and negatively charged silicon dangling bonds, typical for undoped andn-dopeda-Si:H,respectively. Using depth profiling along the growth direction a difference was observed in the electronic environment of these defects, which enables their identification in ap-i-ndevice. ©1998 American Institute of Physics.