Chemical imaging of insulators by STM

被引：45

作者：

Viernow, J ^{[1
]}

Petrovykh, DY ^{[1
]}

Kirakosian, A ^{[1
]}

Lin, JL ^{[1
]}

Men, FK ^{[1
]}

Henzler, M ^{[1
]}

Himpsel, FJ ^{[1
]}

机构：

[1] Univ Wisconsin, Dept Phys, Madison, WI 53706 USA

来源：

PHYSICAL REVIEW B | 1999年 / 59卷 / 15期

关键词：

D O I：

10.1103/PhysRevB.59.10356

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Nanostructures of CaF2 and CaF1 on Si(111) are used to demonstrate a chemical imaging method for insulators. Chemical sensitivity is achieved in scanning tunneling microscopy via a sharp drop of the tunneling current for bias voltages below the conduction-band minimum. This imaging method has a spatial resolution of better than 1 nm and distinguishes different oxidation states. A resonance is found in (dI/dV)/(I/V) at the conduction-band minimum that enables an accurate determination of its position. We observe enhancements by up to a factor of 5 and absolute values in the range of 20-50, compared to 1 for an Ohmic metal. A minimal model is given, explaining the resonance in terms of tunneling across a thin insulator film. These methods should be generally applicable for determining local Schottky barriers and band offsets in nanostructures and for chemically selective imaging of insulators and wide-gap semiconductors. [S0163-1829(99)07215-X].

引用

页码：10356 / 10361

页数：6

共 38 条

[1] Semiconductor clusters, nanocrystals, and quantum dots [J].