Dual-channel microwave scanning probe microscopy for nanotechnology and molecular biology

In this work we describe a new dual-channel scanning probe microscope performing simultaneously Scanning Tunneling Microscopy (STM) and wide-band Near Field Scanning Microwave Microscopy (wide-band SMM). Our SMM system exploits the STM feedback to keep a suitable distance between probe and sample. The system is new because our SMM performs broadband measurements of the reflection coefficient across the STM probe by means of an external VNA with no resonant circuit. A post-processing algorithm reduces the noise by comparing images recorded at different close frequencies.