Kim Zee Hwan, Liu Bing, Leone Stephen R
Department of Chemistry and Physics, University of California, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
J Phys Chem B. 2005 May 5;109(17):8503-8. doi: 10.1021/jp047425i.
Nanometer-scale chemical imaging of epitaxially grown gallium nitride (GaN) and indium nitride (InN) islands is performed using scattering-type apertureless near-field scanning optical microscopy (ANSOM). The scattering of 633 nm laser radiation is modulated by an oscillating metallic probe, and the scattered radiation is detected by homodyne amplification, followed by high-harmonic demodulation, yielding optical near-field scattering maps with a spatial resolution better than 30 nm. The image contrast between InN and GaN, and the tip-sample distance dependence, can be qualitatively explained by a simple dipole-coupling model. The ANSOM images of InN and GaN also show structures that are absent in the topographic counterpart, and these substructures are explained by the variations of the local dielectric environment of InN and GaN.
利用散射型无孔径近场扫描光学显微镜（ANSOM）对外延生长的氮化镓（GaN）和氮化铟（InN）岛进行纳米级化学成像。633 nm激光辐射的散射由振荡金属探针调制，散射辐射通过零差放大检测，然后进行高谐波解调，得到空间分辨率优于30 nm的光学近场散射图。InN和GaN之间的图像对比度以及针尖-样品距离依赖性可以通过一个简单的偶极耦合模型进行定性解释。InN和GaN的ANSOM图像还显示出地形图像中不存在的结构，这些子结构可以通过InN和GaN局部介电环境的变化来解释。
