IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Nanometer Structures Thursday Sessions
       Session NS-ThP

Paper NS-ThP18
Active Feedback Noise Cancellation Low Temperature Scanning Tunneling Spectroscopy

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Poster Session
Presenter: D. Chen, The Rowland Institute for Science
Authors: D. Chen, The Rowland Institute for Science
S.L. Pryadkin, The Rowland Institute for Science
B. Wang, University of Science and Technology of China
H. Wang, University of Science and Technology of China
Correspondent: Click to Email
A scanning tunneling microscope (STM) is one of the most sensitive mechanical and acoustical noise sensors. This in turn makes it difficult to perform fine resolution spectroscopy. Here, we describe a novel UHV and low temperature (4.2K) STM consisting of two tips which can be actuated independently. In the spectroscopy mode, one of the tips serves as the noise sensor whose signal is phase inverted and fed to the second tip to lock the tip-to-sample separation during an I-V measurement. This active feedback method effectively improves the signal-to-noise ratio. More importantly, under the low thermal drift conditions, such as in low temperature operation, it allows the long-time averaging of the measurement while avoiding artifacts due to residual mechanical instability of STM. Examples o the tunneling electron spectroscopy performed on quantized nano-structure will be demonstrated.