We measured the current passing between a sample and a scanning tunneling microscope (STM) tip under conditions of X-ray irradiation. As shown in our previous reports, this STM tip current originated from electron emission on the sample surface. For high precision STM tip current measurement, we applied an X-ray modulation technique using an X-ray chopper and a lock-in amplifier. X-rays modulated by the X-ray chopper irradiated the sample surface of the STM, and the STM tip current was detected using the lock-in amplifier. The largest and most stable output from the lock-in amplifier was obtained under the experimental conditions of low modulation frequency (∼10 Hz), strong X-ray intensity, and high STM bias voltage. Compared with measuring the STM tip current directly without the modulation technique, the precision of this measurement is threefold better.
|ジャーナル||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|号||4 SUPPL. A|
|出版ステータス||Published - 1998 4|
ASJC Scopus subject areas
- Physics and Astronomy(all)