Hydrogenated amorphous silicon studied by scanning tunneling microscopy

We have used scanning tunneling microscopy under ultrahigh vacuum conditions in order to study the local electronic properties, as well as the topographical and chemical structure of hydrogenated amorphous silicon. Local characteristics were measured and images of the topography, as well as simultaneously recorded images of the local tunneling barrier height, were obtained with subnanometer resolution. The experimental results demonstrate that chemical inhomogeneities on a subnanometer scale, which may be caused by the presence of hydrogen in these samples, can be detected in the local tunneling barrier height images.