Charge state dependence of oxygen adatom conductance switching

Abstract

Conductance state of a single atom, which exclusively affects the charge transferring rate, plays a key role in determining the electronic properties of the single atom/molecule devices [1, 2]. Therefore, it is significantly important to precisely characterize and deliberately switch the conductance states of single atoms/molecules. In this study, we systematically investigated the dependence of the oxygen adatom (Oad) conductance switching on its charge states by noncontact atomic force microscopy (nc-AFM) and scanning tunneling microscopy (STM) at 78 K. We firstly clarify the Oad charge and conductance states on rutile TiO2(110) using simultaneous nc-AFM/STM measurement (Figure 1). It suggests that the Oad- has much higher conductance than Oad2-, and the Oad conductance switching between high and low levels can be controlled by deliberately manipulating the Oad charge states through ramping the bias voltage. The charge and conductance states switching of the Oad can be attributed to the tunneling electrons transferring from the tip into the Oad or from the Oad to the substrate polaron [3,4,5]. Our study provides a good reference for the systematic investigation of the atomic conductance, and has a potential overriding effect on revolutionizing the investigation of the single atom/molecule devices.