Low-temperature UHV scanning tunneling microscope double sample holder for <i>in situ</i> exchangeable clean room processed samples

A generalization of the double sample holder (DSH) concept is presented for an ultra-high vacuum (UHV) low-temperature (LT) multi-probe scanning tunneling microscope (STM). In UHV, the DSH is carrying, side-by-side, a reference metal sample [Au(111) single crystal for STM tip apex preparation] and an ancillary stand-alone small sample holder (for samples originating from a clean room) that can be mounted in situ in/out of the DSH plate. STM tip navigation on both sample surfaces is performed using a UHV scanning electron microscope positioned above the STM stage. For demonstration, clean room nanofabricated graphene nano-gears (diameter down to 25 nm) on a sapphire sample are characterized using STM. The STM tip apices are cleaned on the atomically precise and UHV cleaned Au(111) reference sample surface. Using our new DSH plate and in situ STM tip apex re-preparation on the reference metallic sample, we demonstrate how a clean room originating sample can be imaged at the atomic resolution using our LT-UHV 4-STM.