Point defects, dopant atoms, and compensation effects in CdSe and CdS cleavage surfaces

We investigated point defects and dopant atoms in (11 (2) over bar 0) and ( 10 (1) over bar 0) cleavage surfaces of CdSe using atomically resolved scan ning tunneling microscopy images. Positively charged dopant atoms give rise to elevations of up to 5 nm in diameter in the empty and occupied state im ages. Uncharged Se and Cd Vacancies exhibit an isolated missing occupied an d empty dangling bond, respectively. In CdS (10 (1) over bar 0) surfaces we observed In dopant atoms and accepters. On the basis of the observed defec ts and dopant atoms and their concentrations the origin of the electrical c ompensation is discussed. (C) 1999 Elsevier Science S.A. AII rights reserve d.