Electronic Spectroscopies by a Novel STM with functional Semiconductor Tips

通过具有功能性半导体尖端的新型 STM 进行电子光谱

基本信息

批准号：
09650381
负责人：
TAKAHASHI Takuji
金额：
$ 1.86万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650381/
关键词：
Scanning Tunneling Microscopy Semiconductor Tips Laser Irradiation Photo-excited Carriers Surface Depletion AFM with a Conductive Tip Electrostatic Force Self-assembled Dots 半導性探針AFM 微分コンダクタンスバンドギャップ表面光起電力効果

项目摘要

In order to find the proper semiconductor materials for STM tips, we have characterized the near surface electrical properties of self-assembled InAs dot-covered surfaces on n-GaAs through both the STM/STS measurements under the laser irradiation and the electrostatic force measurements by AEM with a conductive tip.We characterized the near surface electrical properties of The self-assembled InAs dot-covered surfaces on n-GaAs through the STM/STS measurements under the laser irradiation. As a result, the small photo-response signal was detected near the InAs dot structures, while the large signal was detected from the surrounding wetting layer region. In addition, the time-resolved tunneling current measurements revealed that such photo-response signal mainly came from the reduction of the surface depletion due to the photo-excited carries. These results indicates that the surface depletion is suppressed near the InAs dots, which is very similar as the bulk InAs surface where the electrons are accumulated.We measured the electrostatic force, which is working between the AFM tip and the sample, on the similar sample as above by the AEM with a conductive tip. Through the lock-in detection technique at the two frequencies which are the same and the double frequencies as applied AC bias frequency, we succeeded in estimating the degree of surface depletion. Moreover, the obtained electrostatic force data clearly indicated that the surface depletion is suppressed near the InAs dots, which is consistent with the STM/STS results.As a result, InAs covered-GaAs is one of the promising materials for the semiconductor tip because the surface depletion is suppressed on its surface.

为了找到适当的STM尖端半导体材料，我们表征了N-GAA上自组装的INAS DOT覆盖表面的近表面电气特性，通过激光辐照下的STM/STS测量以及通过静电力测量在N-GAAS上进行的测量。我们的AEM具有导电尖端。我们表征了通过激光照射下的STM/STS测量值在N-GAAS上自组装的INAS点覆盖的表面的近表面电气性能。结果，在INAS点结构附近检测到小的光响应信号，而从周围的润湿层区域中检测到了大信号。此外，时间分辨的隧穿电流测量结果表明，这种光响应信号主要来自由于光激发的携带而导致的表面耗竭。这些结果表明，表面耗竭在INAS点附近被抑制，这与电子累积的散装INAS表面非常相似。我们测量了在AFM尖端和样品之间工作的静电力，该静电力在相似的样品上起作用。如上所述，AEM带有导电尖端。通过在两个频率相同的锁定检测技术和与应用AC偏置频率相同的双频率的情况下，我们成功地估计了表面耗竭的程度。此外，获得的静电力数据清楚地表明，在INAS点附近抑制了表面耗竭，这与STM/STS结果一致。由于结果，INAS覆盖的GAA是半导体尖端的有前途的材料之一，因为表面耗竭在其表面被抑制。