Scanning tunneling microscopy and spectroscopy of atomic modifications on WSe2

In this paper we study the imaging process of atomic-size and extended modifications in WSe2 by taking spectroscopic data. Due to the soft character of layered materials, the tip-sample interaction plays an important role in STM. Therefore, we have carefully analysed the distance and bias voltage dependence of the tunneling current on bare and modified regions. From this data, we conclude that atomic-size topographic defects could be imaged as extended structures, though a local change in the electronic properties could produce similar results. On atomic-size structures the spectroscopic measurements reveal a change in the electronic structure of the modified areas. The shape of these "trimer" structures could be due to a change in the tungsten atom position. (C) 1998 Elsevier Science B.V.