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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 ZnTe(110) surface (Vs = −1.5 V, It = 60 pA). (b) High-resolution image of ZnTe(110) surface (Vs = −2.0 V, It = 20 pA). (c) Schematic structures of ZnTe(110) surface.
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Figure 1: (a) STM image of ZnTe(110) surface (Vs = −1.5 V, It = 60 pA). (b) High-resolution image of ZnTe(110) surface (Vs = −2.0 V, It = 20 pA). (c) Schematic structures of ZnTe(110) surface.

Mentions: Comparing to group IV or III–V semiconductors, however, the ZnTe surface has not been well comprehended. Moreover, reported studies are mainly concerned with static surface properties such as atomic structure and electronic ground state, but dynamic phenomena on the surface have been largely uncertain. ZnTe(110) surface states, which are the topic of this paper, have been studied by low-energy electron diffraction [7], scanning tunneling microscopy (STM) [8, 9], angle-resolved photoelectron spectroscopy (ARPES) [10], electron energy loss spectroscopy (EELS) [11] and density functional theory (DFT) calculations [12]. These results have revealed that the topmost cationic and anionic atoms are slightly displaced toward the inside of the crystal and vacuum from the ideal (110) structures of truncated bulk crystal, respectively, and the atomic arrangement of ZnTe(110) surface is fundamentally similar to that of III–V semiconductor surfaces (hereafter referred to as the reconstructed surface). The STM observations, however, showed that this surface is unstable and friable, i.e., line defects tend to be generated along the 〈110〉 direction (figure 1(a)) when a clean surface is obtained by cleavage [8, 9]. In addition, when the surface is scanned by STM with a positive sample bias voltage, surface atoms are often desorbed from the surface [8]. These characteristics are unique and markedly different from those of IV and III–V semiconductor surfaces.


Dynamic probe of ZnTe(110) surface by scanning tunneling microscopy
(a) STM image of ZnTe(110) surface (Vs = −1.5 V, It = 60 pA). (b) High-resolution image of ZnTe(110) surface (Vs = −2.0 V, It = 20 pA). (c) Schematic structures of ZnTe(110) surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: (a) STM image of ZnTe(110) surface (Vs = −1.5 V, It = 60 pA). (b) High-resolution image of ZnTe(110) surface (Vs = −2.0 V, It = 20 pA). (c) Schematic structures of ZnTe(110) surface.
Mentions: Comparing to group IV or III–V semiconductors, however, the ZnTe surface has not been well comprehended. Moreover, reported studies are mainly concerned with static surface properties such as atomic structure and electronic ground state, but dynamic phenomena on the surface have been largely uncertain. ZnTe(110) surface states, which are the topic of this paper, have been studied by low-energy electron diffraction [7], scanning tunneling microscopy (STM) [8, 9], angle-resolved photoelectron spectroscopy (ARPES) [10], electron energy loss spectroscopy (EELS) [11] and density functional theory (DFT) calculations [12]. These results have revealed that the topmost cationic and anionic atoms are slightly displaced toward the inside of the crystal and vacuum from the ideal (110) structures of truncated bulk crystal, respectively, and the atomic arrangement of ZnTe(110) surface is fundamentally similar to that of III–V semiconductor surfaces (hereafter referred to as the reconstructed surface). The STM observations, however, showed that this surface is unstable and friable, i.e., line defects tend to be generated along the 〈110〉 direction (figure 1(a)) when a clean surface is obtained by cleavage [8, 9]. In addition, when the surface is scanned by STM with a positive sample bias voltage, surface atoms are often desorbed from the surface [8]. These characteristics are unique and markedly different from those of IV and III–V semiconductor surfaces.

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.