Creation of a <i>p</i>-type TlBiSe₂ using photo-induced doping

Abstract

Owing to the location of the Dirac point, which is around the center of its wide bulk band gap, TlBiSe2 would be one of the most promising topological insulators for spintronics devices material. However, like many other topological insulators, defects, such as vacancy formed during the crystal growth, dope electrons into TlBiSe2 and make its bulk metallic. Here, we show the achievement of bulk insulating both n-type and p-type TlBiSe2 by photo-induced doping, a method carried out by a combination of photo-irradiation and H2O adsorption. We also show that the main trigger of this photo-induced doping is the excitation of the outermost d core level of the chalcogen atoms of the topmost layer as in the case of Bi2X3, where X = Se or Te.