| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1997: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
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.
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