Supporting Information
Characterization of the Photocurrents Generated by the Laser of Atomic Force Microscopes
Yanfeng Ji1, Fei Hui1, Yuanyuan Shi1, Vanessa Iglesias2, David Lewis3, Jiebin Niu4, Shibing Long4, Ming Liu4, Alexander Hofer5, Werner Frammelsberger5, Guenther Benstetter5, Andrew Scheuermann6, Paul C. McIntyre6 and Mario Lanza1, *
1Institute of Functional Nano and Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nanoscience and Technology, Soochow University, 199 Ren-Ai Road, Suzhou, 215123, China
2International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
3Nanonics Imaging, Har Hotzvim, Jerusalem 91487, Israel
4Laboratory of Nanofabrication and Novel Device Integration, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China
5Deggendorf Institute of Technology, Edlmairstr. 6+8, 94469 Deggendorf, Germany
6Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
*Corresponding author E-mail:
Figure S1: Topographic (left) and current (right) maps for the Ir/TiO2/SiO2/n-Si sample in vacuum. The size of the images is 500 nm x 500 nm. The high currents observed in vacuum (here) are similar to those obtained in air (Figure 1e of the manuscript), indicating that the currents are not generated by electrochemical reactions related to the capilary layer on the surface of the sample.
Figure S2. Optical microscope image of the CAFM tip with the laser at its back side. In the correct calibration the laser is in the center of the tip, and the value of the SUM is the largest, but there is still a large amount of light from the laser impacting on the sample (white arrows).
Figure S3: Table of CAFM current maps and the corresponding cross sections of the Ni/SiO2/n-Si sample. The electrodes we measured are with different sizes, which are 100µm, 50µm, 25µm, 20µm, 15µm, 10µm. The cross sections show the same current signals, which means these electrodes show the same photocurrent. The scan size for the current maps are 5µm x 5 µm.
Figure S4: Table of SEM (left), CAFM current maps (middle) and cross sections (right) with different sizes of the electrodes of sample Ni/SiO2/n-Si. The scales of the SEM images are 10µm, 1µm, 300nm, 200nm, respectively. The scan sizes for the current maps are 2µm, 500nm, 600nm and 1µm. For the first two rows, the maps are collected on the Ni electrode; For the third row we collected at the boundary of one electrode, while for the fourth row the electrodes are so small that we collected a picutre that includes four electrodes. For visualizing clearly the small currents, the vertical Z-scale has been modified respect to figure S4.It can be observed that the current decreases when the size of electrode getting smaller, which can also be proved by the cross section.
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