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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 of a ZnTe surface obtained before the electron injection treatment (Vs = −3.0 V, It = 1.0 nA). (b) Typical temporal change of the current obtained during the treatment. (c), (d), (e) STM images after the treatment with three different electron injection times of ti ((c) 0.1 s, (d) 0.3 s, (e) 0.5 s, Vs = +1.5 V, It = 30 pA). D1 to D4 are surface defects induced by each treatment. D3 in (d) and (e) indicate exactly the same defect. Black arrows indicate clusters of atoms desorbed by the manipulation.
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Figure 6: (a) STM image of a ZnTe surface obtained before the electron injection treatment (Vs = −3.0 V, It = 1.0 nA). (b) Typical temporal change of the current obtained during the treatment. (c), (d), (e) STM images after the treatment with three different electron injection times of ti ((c) 0.1 s, (d) 0.3 s, (e) 0.5 s, Vs = +1.5 V, It = 30 pA). D1 to D4 are surface defects induced by each treatment. D3 in (d) and (e) indicate exactly the same defect. Black arrows indicate clusters of atoms desorbed by the manipulation.

Mentions: Figure 6(a) shows the surface observed before the treatment. Figure 6(b) shows a typical time-resolved spectrum, i.e., the tunneling current as a function of time, in which tmes = 0 corresponds to the moment when the tunneling current was set to +0.03 nA, similarly to the case shown in figure 3(d). The tunneling current jumped from 0.03 to ∼5 nA and then disappeared. Figure 6(c) shows the STM image after the treatment with the injection time of ti = 0.1 s, in which an atomic-scale defect was generated. Namely, the jump in tunneling current shown in figure 6(b) is considered to correspond to the desorption of the surface Zn atom. To confirm this result, we carried out the same process with increased electron injection times ti to 0.3 s and 0.5 s, the results of which are shown in figures 6(d) and (e), respectively. Larger defects were generated with increasing ti, and clusters considered to be formed by the removal of atoms were observed, as indicated by arrows. After the desorption of the Zn atom immediately below the STM tip, the adjacent Zn atoms may have been desorbed depending on the injection time. Further analysis is necessary to determine in detail the conditions required for desorption. Although the lengths of the defects were short, their appearances were very similar to the intrinsic line defect on the ZnTe(110) surface shown in figure 1(a) in that they run along the 〈110〉 direction with single-atomic-row-width on the surface.


Dynamic probe of ZnTe(110) surface by scanning tunneling microscopy
(a) STM image of a ZnTe surface obtained before the electron injection treatment (Vs = −3.0 V, It = 1.0 nA). (b) Typical temporal change of the current obtained during the treatment. (c), (d), (e) STM images after the treatment with three different electron injection times of ti ((c) 0.1 s, (d) 0.3 s, (e) 0.5 s, Vs = +1.5 V, It = 30 pA). D1 to D4 are surface defects induced by each treatment. D3 in (d) and (e) indicate exactly the same defect. Black arrows indicate clusters of atoms desorbed by the manipulation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: (a) STM image of a ZnTe surface obtained before the electron injection treatment (Vs = −3.0 V, It = 1.0 nA). (b) Typical temporal change of the current obtained during the treatment. (c), (d), (e) STM images after the treatment with three different electron injection times of ti ((c) 0.1 s, (d) 0.3 s, (e) 0.5 s, Vs = +1.5 V, It = 30 pA). D1 to D4 are surface defects induced by each treatment. D3 in (d) and (e) indicate exactly the same defect. Black arrows indicate clusters of atoms desorbed by the manipulation.
Mentions: Figure 6(a) shows the surface observed before the treatment. Figure 6(b) shows a typical time-resolved spectrum, i.e., the tunneling current as a function of time, in which tmes = 0 corresponds to the moment when the tunneling current was set to +0.03 nA, similarly to the case shown in figure 3(d). The tunneling current jumped from 0.03 to ∼5 nA and then disappeared. Figure 6(c) shows the STM image after the treatment with the injection time of ti = 0.1 s, in which an atomic-scale defect was generated. Namely, the jump in tunneling current shown in figure 6(b) is considered to correspond to the desorption of the surface Zn atom. To confirm this result, we carried out the same process with increased electron injection times ti to 0.3 s and 0.5 s, the results of which are shown in figures 6(d) and (e), respectively. Larger defects were generated with increasing ti, and clusters considered to be formed by the removal of atoms were observed, as indicated by arrows. After the desorption of the Zn atom immediately below the STM tip, the adjacent Zn atoms may have been desorbed depending on the injection time. Further analysis is necessary to determine in detail the conditions required for desorption. Although the lengths of the defects were short, their appearances were very similar to the intrinsic line defect on the ZnTe(110) surface shown in figure 1(a) in that they run along the 〈110〉 direction with single-atomic-row-width on the surface.

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.