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11 November 1999 Photoexcitation-induced current sensing on semi-insulating GaAs using a tunneling microscope tip
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Proceedings Volume 3897, Advanced Photonic Sensors and Applications; (1999)
Event: International Symposium on Photonics and Applications, 1999, Singapore, Singapore
Detailed tunneling current measurements using a tunneling microscope tip have been performed on semi-insulating GaAs surfaces as a function of illumination power, Pt/Ir tip- surface distance, and separation between the tip and In/Ga electrode on the sample surface to elucidate previously unsolved problems of illumination-induced thermal expansion effects on the probe and of the surface depletion effects. We show that the tip-sample distance to detect a constant tunneling current is extended with increasing the otpical excitation power. It is also found that the photo-induced tunneling current as high as 8 nA driven by a 746 nm laser diode is linearly proportional to the optical excitation power. This photo-induced carriers conduction is also confirmed by studying the transient photocurrent responses, which is slowed down by increasing the tip-to-electrode distance. These results reveal that, in our case, the thermal effects are negligible and photogenerated electron tunneling is a dominant mechanism for the increased tunneling current from the samples surface biased at negative voltages relative to the tip.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kenji Kawashima, Shinji Takai, Gou Kudou, Hideo Adachi, Misaichi Takeuchi, and Kenzo Fujiwara "Photoexcitation-induced current sensing on semi-insulating GaAs using a tunneling microscope tip", Proc. SPIE 3897, Advanced Photonic Sensors and Applications, (11 November 1999);

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