Electronic states of simple-transition-metal impurities in silicon

The $X\alpha$ scattered-wave cluster method has been used to investigate the electronic properties associated with simple substitutional transition-metal impurities in silicon. The impurities studied were chosen from the $3d$ row of the periodic table and include chromium, cobalt, nickel, copper, and zinc. In all cases the defect behavior (donor or acceptor) has been correctly determined, and the calculated position of the corresponding defect level in the gap has been found to be in good agreement with the measured values in all cases except that of cobalt. Trends in the electronic behavior of $3d$ transition metal defects are discussed and correlated with the local bonding properties of the host-defect system.