Methods and devices configured to operated scanning tunneling microscopes using out-of-bandwidth frequency components added to bias voltage and related software

One or more non-transitory processor-readable media storing processor-executable instructions for causing one or more processors to perform a method of operating a scanning tunneling microscope (STM), the method comprising:

• applying a time-varying voltage signal between a tip of the STM and a surface of a sample located beneath the tip, the time-varying voltage signal comprising a dc bias voltage modulated with a dither voltage signal having a dither frequency and dither amplitude;
• receiving a time varying tip-sample current signal, including components at the dither frequency, tunneling between the tip and the sample;
• and
• filtering the time varying tip-sample current signal to attenuate the components at the dither frequency to provide a filtered tip-sample current signal.

A method of operating a scanning tunneling microscope (STM), the method comprising:

• applying a time-varying voltage signal between a tip of the STM and a surface of a sample located beneath the tip, the time-varying voltage signal comprising a dc bias voltage modulated with a dither voltage signal having a dither frequency and dither amplitude;
• receiving a time varying tip-sample current signal, including components at the dither frequency, tunneling between the tip and the sample;
• filtering the time varying tip-sample current signal to attenuate the components at the dither frequency to provide a filtered tip-sample current signal to generate a topographical image data of the sample;
• and
• applying the time varying tip-sample current signal to an input of a lock-in amplifier to generate an ac tunneling current by subtracting a capacitive current component from the time varying tip-sample current signal to provide spectroscopic data of the sample.

A method of operating a scanning tunneling microscope (STM), the method comprising:

• applying a time-varying voltage signal between a tip of the STM and a surface of a sample located beneath the tip, the time-varying voltage signal comprising a dc bias voltage modulated with a dither voltage signal having a dither frequency and dither amplitude;
• receiving a time varying tip-sample current signal, including components at the dither frequency, tunneling between the tip and the sample;
• and
• applying the time varying tip-sample current signal to an input of a lock-in amplifier to subtract a capacitive current component from the time varying tip-sample current signal to provide magnitude of an ac component of tunneling current as an input to a control feedback loop of the STM.