Microscopic identification of dopant atoms in Mn-doped GaAs layers

Using cross-sectional scanning tunneling microscopy (XSTM), we have identified the dopant atoms, in Mn-doped GaAs layers grown at 400 degreesC by molecular-beam epitaxy. The Mn-dopant atoms appeared as diffuse light areas superimposed on the background of As atomic rows, in the STM images. The Mn acceptor concentration deduced from the STM images agreed well with the hole concentration determined by Hall measurements. No As antisite and associated defects were observed. These results indicate that Mn atoms are incorporated into the GaAs layer as electrically activated acceptors. (C) 2002 Elsevier Science Ltd. All rights reserved.