STM / STS measurements of Mn atoms in Group III-V semiconductors

摘要

Diluted magnetic semiconductor (DMSs) are semiconductors doped with magnetic atoms. For practicaluse, it is necessary to clarify the electronic states around the magnetic atoms. Recent scanning tunnelingmicroscopy (STM) measurements revealed the hole state bound to a Mn acceptor in III-V semiconductorssuch as GaAs[1], InAs[2] and InSb[3]. It was shown by STM that the hole state bound to a Mn acceptor inIII-V semiconductors has a strongly anisotropic shape which is even more pronounced at cleaved (110)surfaces. This anisotropy is caused by the strain field of the surface relaxation and the tip-induced electricfield[4]. Also, it is known that the appearance of the STM image changes depending on the depth of theacceptor level. At a fixed depth, the charge distribution of a deep acceptor, such as Mn in GaAs and InAs, ischaracterized by a bow-tie shape whereas the shape of the charge distribution of a shallow acceptor, such asZn in GaAs and Mn in InSb, is triangular.