Servomechanism for locking scanning tunneling microscope tip over surface nanostructures

Measurement of the light emission spectrum from a scanning tunneling micros cope (STM) requires a long exposure time due to its extremely low intensity , and thermal drift of the tip during the exposure time limits the spatial resolution. To improve the resolution, a computer controlled servomechanism that locks the STM tip over a target position has been developed. We have measured the light emission spectra from individual nanometer scale structu res on an evaporated Au film with and without this mechanism, and demonstra ted the effectiveness of the servomechanism. (C) 2000 American Institute of Physics. [S0034-6748(00)01702-0].