A versatile microwave-frequency-compatible scanning tunneling microscope

Challenged by the need to transmit a microwave frequency signal to and from the tunnel junction of a scanning tunneling microscope (STM), an STM has been designed and built that provides 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 a flexible feedback scheme allowing selection of the required piezoelectric gain and stability. A reliable, easy to fabricate sample approach is also described that adds to the stability of this design. 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 is demonstrated.