| 摘要 |
PROBLEM TO BE SOLVED: To provide a new device/method for directly detecting a light absorbing material by a nano-scale by means of a scanning tunnel microscope STM probe. SOLUTION: A chopper 6 intermittently radiates a gap beam (a wavelength 788 nm, 12 mW/mm2) at an incident angle 45 deg. onto a p-GaAs 10 surface with a high modulation frequency beyond follow-up by a constant current control of the STM. A lock-in amplifier 3 lock-in detects a modulated tunnel current waveform. It so as to find a tunnel current amplitudeΔI. In a two-dimensional distribution image based on this, a bright contrast part not existing in an ordinary STM topographic image is observed. This is because heat locally generated by non-light emission recombination in an isolated defect beneath the sample 10 surface is dispersed to the circumference and causes a great thermal expansion displacement on the surface around the defect specially. In this way, a defect in the sample 10 can be detected.
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