A Versatile Microwave-Frequency-Compatible Scanning Tunneling Microscope

S. J. Stranick and P. S. Weiss *

Review of Scientific Instruments 64, 1232 (1993); ibid. 64, 2039 (1993).

Challenged by the need to transmit a microwave frequency signal to and from the tunnel junction of a scanning tunneling microscope (STM), we have designed and built an STM that provides us with minimal microwave signal loss. The STM has been operated over a wide frequency range, DC to 20 GHz, without the use of a microwave resonance cavity. This design also provides us with a flexible feedback scheme allowing us to select the required piezoelectric gain and stability. A reliable, easy to fabricate sample approach is also described that adds to the stability of this design. We demonstrate the operation of this microscope by imaging a lead silicate glass surface with a bias voltage modulation frequency and detection frequency of 7.73 GHz.