A low-temperature scanning probe microscopy system with molecular beam epitaxy and optical access

Abstract

A low-temperature (LT) ultra-high vacuum (UHV) scanning probe microscopy (SPM) system with molecular beam epitaxy (MBE) capability and optical access was conceived, built, and tested in our lab. The design of the whole system is discussed here, with special emphasis on some critical parts. We made an SPM scanner head with a modified Pan-type design, enclosed by a double-layer cold room under a bath type cryostat. The scanner head is very rigid, compatible with optical access paths, and can accommodate both scanning tunneling microscope (STM) tips and atomic force sensors. Two piezo-actuated focus-lens stages are mounted on the two sides of the cold room to couple light in and out. To demonstrate the system's performance, we performed STM and scanning tunneling spectroscopy (STS) studies. The herringbone reconstruction and atomic structure of Au(111) surface were clearly resolved. The dI/dV spectra of an Au(111) surface were obtained at 5 K. In addition, a periodic 2D tellurium (Te) structure was grown on Au(111) surface using MBE.

Atomic-Scale Dynamics Probed by Photon Correlations

“…The setup comprises a low-temperature (4 K), ultrahigh vacuum (UHV) STM with three independent free space optical access pathways for time-resolved detection systems situated in the ambient. It is one of a few similar set-ups in the field. ,− In order to address ultrafast phenomena, the electroluminescence detection is performed by single-photon avalanche photodiodes (SPADs) with 30 ps time resolution (equal to the output pulse jitter with respect to photon arrival) and by an optical spectrometer coupled to an intensifier-gated charge-coupled device (CCD) camera with a minimum gate width of 5 ns. In the following, we distinguish between the Hanbury Brown–Twiss STM (HBT-STM, photon–photon correlation) and time-resolved STML (TR-STML, voltage pulse–photon correlation) modes of operation.…”

A compact, friction self-matching, non-inertial piezo motor with scanning capability

“…But, the piezoelectric stacks are used to clamp the output shaft to generate contact forces [23] in inchworm PMs, which resulting in a larger size and may fail due to the drastic reduction of the piezoelectric coefficient at low temperature. The Pan-type PM adopts six independently controllable shear-piezo stacks to elastically hold the slider; these nicely balance the friction, making it widely used in the field of low-temperature and high-magnetic field scanning probe microscopy [24][25][26], but its low integrity and high complexity limit its application in compact environments. Although the PandaDrive is considerably smaller than a Pantype motor, it is necessary to ensure that the frictional forces at its three contacts have an appropriate relationship.…”