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Dynamic probe of ZnTe(110) surface by scanning tunneling microscopy

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ABSTRACT

The reconstructed surface structure of the II–VI semiconductor ZnTe (110), which is a promising material in the research field of semiconductor spintronics, was studied by scanning tunneling microscopy/spectroscopy (STM/STS). First, the surface states formed by reconstruction by the charge transfer of dangling bond electrons from cationic Zn to anionic Te atoms, which are similar to those of IV and III–V semiconductors, were confirmed in real space. Secondly, oscillation in tunneling current between binary states, which is considered to reflect a conformational change in the topmost Zn–Te structure between the reconstructed and bulk-like ideal structures, was directly observed by STM. Third, using the technique of charge injection, a surface atomic structure was successfully fabricated, suggesting the possibility of atomic-scale manipulation of this widely applicable surface of ZnTe.

No MeSH data available.


(a) STM image before the electron-injection sequence with Vs = +1.5 V and It = 0.3 nA (Vs = −3.0 V, It = 1.0 nA). (b) Temporal change of the current obtained during the electron-injection sequence carried out on the area indicated by dotted lines. (c) STM image of the surface defects generated by the electron-injection sequence (Vs = −3.0 V, It = 1.0 nA).
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Figure 5: (a) STM image before the electron-injection sequence with Vs = +1.5 V and It = 0.3 nA (Vs = −3.0 V, It = 1.0 nA). (b) Temporal change of the current obtained during the electron-injection sequence carried out on the area indicated by dotted lines. (c) STM image of the surface defects generated by the electron-injection sequence (Vs = −3.0 V, It = 1.0 nA).

Mentions: Next, we consider the relationship between the structural oscillations and the atomic desorption from the surface induced by STM observation at a positive sample bias voltage in the previous study. No damage reflecting the atomic desorption was observed with the measurement condition of the STS measurement (figure 1) and during the above STM sequence (figure 3) in this study. However, the atomic desorption occurred when we used the setpoint tunneling current of ten times larger, I = 0.3 nA. Figures 5(a) and (c) show the STM images obtained before and after the electron injection sequence shown in figure 3, which was carried out at the grid points of the mesh drawn in figure 5(a). Formation of defects is clearly shown in figure 5(c). When the surface Zn atom is displaced toward to the vacuum by the electron injection, tunneling current increases. In fact, much larger tunneling current, which exceeded the detection limits of 5 nA was observed during the electron injection as shown in figure 5(b), which might induce the atomic desorption as a result of an enhancement of the atomic oscillation.


Dynamic probe of ZnTe(110) surface by scanning tunneling microscopy
(a) STM image before the electron-injection sequence with Vs = +1.5 V and It = 0.3 nA (Vs = −3.0 V, It = 1.0 nA). (b) Temporal change of the current obtained during the electron-injection sequence carried out on the area indicated by dotted lines. (c) STM image of the surface defects generated by the electron-injection sequence (Vs = −3.0 V, It = 1.0 nA).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036505&req=5

Figure 5: (a) STM image before the electron-injection sequence with Vs = +1.5 V and It = 0.3 nA (Vs = −3.0 V, It = 1.0 nA). (b) Temporal change of the current obtained during the electron-injection sequence carried out on the area indicated by dotted lines. (c) STM image of the surface defects generated by the electron-injection sequence (Vs = −3.0 V, It = 1.0 nA).
Mentions: Next, we consider the relationship between the structural oscillations and the atomic desorption from the surface induced by STM observation at a positive sample bias voltage in the previous study. No damage reflecting the atomic desorption was observed with the measurement condition of the STS measurement (figure 1) and during the above STM sequence (figure 3) in this study. However, the atomic desorption occurred when we used the setpoint tunneling current of ten times larger, I = 0.3 nA. Figures 5(a) and (c) show the STM images obtained before and after the electron injection sequence shown in figure 3, which was carried out at the grid points of the mesh drawn in figure 5(a). Formation of defects is clearly shown in figure 5(c). When the surface Zn atom is displaced toward to the vacuum by the electron injection, tunneling current increases. In fact, much larger tunneling current, which exceeded the detection limits of 5 nA was observed during the electron injection as shown in figure 5(b), which might induce the atomic desorption as a result of an enhancement of the atomic oscillation.

View Article: PubMed Central - PubMed

ABSTRACT

The reconstructed surface structure of the II–VI semiconductor ZnTe (110), which is a promising material in the research field of semiconductor spintronics, was studied by scanning tunneling microscopy/spectroscopy (STM/STS). First, the surface states formed by reconstruction by the charge transfer of dangling bond electrons from cationic Zn to anionic Te atoms, which are similar to those of IV and III–V semiconductors, were confirmed in real space. Secondly, oscillation in tunneling current between binary states, which is considered to reflect a conformational change in the topmost Zn–Te structure between the reconstructed and bulk-like ideal structures, was directly observed by STM. Third, using the technique of charge injection, a surface atomic structure was successfully fabricated, suggesting the possibility of atomic-scale manipulation of this widely applicable surface of ZnTe.

No MeSH data available.