A LOW-TEMPERATURE SCANNING TUNNELING MICROSCOPE WITH INSITU SAMPLE CLEAVING

We present the design of a scanning tunneling microscope (STM) that is operated in an ultra-high vacuum (UHV) chamber at room temperature and can be lowered into a standard helium cryostat and cooled with helium exchange gas to low temperatures. Central to the design of our system is a compact concentric tube scanning tunneling microscope in which the central tube serves as the scanner and the outer tube allows linear inertial translation of the sample by slip-stick motion. The fact that no mechanical connections are needed to approach the sample and tip allows great flexibility in the design of the system and the vibration isolation of the STM. Samples are cleaved in-situ in the UHV chamber. The stability of the instrument is demonstrated with images of both graphite and the high-temperature superconductor Bi2Sr2Ca1Cu2O8 obtained in UHV (P = 2 x 10(-10) Torr) at room temperature.