We report a study of the lateral band bending at the Ge-GaSe interface. Spectromicroscopy measurements with synchrotron radiation were performed at the ESCA microscopy line of ELETTRA in Ge patterned films on GaSe substrates. Preliminary results of lateral band bending, chemical reactions and the beam stimulated Ge surface migration are presented. These studies allowed us to seek on the microscopical equivalent of the semiconductor Debye length and to probe the capabilities of scanning-focused spectromicroscopical systems.