Compensation mechanisms in low-temperature-grown Ga[sub 1-x]Mn[sub x]As investigated by scanning tunneling spectroscopy.

Ga[sub 1-x]Mn[sub x]As layers with Mn composition of up to 6.2% are investigated by cross-sectional scanning tunneling microscopy and spectroscopy. We identify in the tunneling spectra contributions from Mn[sup -, sub Ga] acceptor states, compensating As[sup 2+, sub Ga] donor states, and additional compensating donor states, which we suggest to be Mn[sup 2+, sub i] interstitials. On basis of the observed Fermi level shift and a charge carrier compensation analysis, we deduce the concentration of Mn[sup 2+, sub i] interstitials. Furthermore, scanning tunneling microscopy images suggest an inhomogeneous distribution of Mn dopant atoms. [ABSTRACT FROM AUTHOR]