title: Characterization of the photocurrents generated by the laser of atomic force microscopes.
abstract: The conductive atomic force microscope (CAFM) has become an essential tool for the nanoscale electronic characterization of many materials and devices. When studying photoactive samples, the laser used by the CAFM to detect the deflection of the cantilever can generate photocurrents that perturb the current signals collected, leading to unreliable characterization. In metal-coated semiconductor samples, this problem is further aggravated, and large currents above the nanometer range can be observed even without the application of any bias. Here we present the first characterization of the photocurrents introduced by the laser of the CAFM, and we quantify the amount of light arriving to the surface of the sample. The mechanisms for current collection when placing the CAFM tip on metal-coated photoactive samples are also analyzed in-depth. Finally, we successfully avoided the laser-induced perturbations using a two pass technique: the first scan collects the topography (laser ON) and the second collects the current (laser OFF). We also demonstrate that CAFMs without a laser (using a tuning fork for detecting the deflection of the tip) do not have this problem.
authors: Institute of Functional Nano and Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nanoscience and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123, China.
authors: Yanfeng
authors: Y
authors: Ji
authors: Institute of Functional Nano and Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nanoscience and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123, China.
authors: Fei
authors: F
authors: Hui
authors: Institute of Functional Nano and Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nanoscience and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123, China.
authors: Yuanyuan
authors: Y
authors: Shi
authors: International Iberian Nanotechnology Laboratory, 4715-330 Braga, Portugal.
authors: Vanessa
authors: V
authors: Iglesias
authors: Nanonics Imaging, Har Hotzvim, Jerusalem 91487, Israel.
authors: David
authors: D
authors: Lewis
authors: Laboratory of Nanofabrication and Novel Device Integration, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China.
authors: Jiebin
authors: J
authors: Niu
authors: Laboratory of Nanofabrication and Novel Device Integration, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China.
authors: Shibing
authors: S
authors: Long
authors: Laboratory of Nanofabrication and Novel Device Integration, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China.
authors: Ming
authors: M
authors: Liu
authors: Deggendorf Institute of Technology, Edlmairstr. 6+8, 94469 Deggendorf, Germany.
authors: Alexander
authors: A
authors: Hofer
authors: Deggendorf Institute of Technology, Edlmairstr. 6+8, 94469 Deggendorf, Germany.
authors: Werner
authors: W
authors: Frammelsberger
authors: Deggendorf Institute of Technology, Edlmairstr. 6+8, 94469 Deggendorf, Germany.
authors: Guenther
authors: G
authors: Benstetter
authors: Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
authors: Andrew
authors: A
authors: Scheuermann
authors: Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
authors: Paul C
authors: PC
authors: McIntyre
authors: Institute of Functional Nano and Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nanoscience and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123, China.
authors: Mario
authors: M
authors: Lanza