# Presentation: 939585

## Characteristics of the MBE1 Endstation at PNC/XOR

**Characteristics of the MBE1 Endstation at PNC/XOR**

- References:
- R. A. Gordon, E. D. Crozier, D. T. Jiang, T. L. Monchesky, B. Heinrich, "Distorted iron films on GaAs(001)-(4X6)," Phys. Rev. B 62 (3), July, 2151-2157 (2000).
- R. A. Gordon, E. D. Crozier, J. Shoults, D. T. Jiang, "Ultrahigh vacuum-compatible fluorescence x-ray absorption fine structure detector," Rev. Sci. Instrum. 73 (8), August, 2849-2851 (2002).
- R. A. Gordon, E.D. Crozier, D.-T. Jiang, P.S. Budnik, T.L. Monchesky, B. Heinrich, "In-situ XAFS study of Fe epitaxially grown by MBE on GaAs(001)-4x6," Surf. Sci. **581** (1), April, 47-57 (2005).

- Acknowledgements:
- The MBE1 system was designed and constructed with the assistance of NSERC, Simon Fraser University Technical Centre and the University of Washington. We would like to thank K. Myrtle and B. Heinrich of the SFU Surface Physics Laboratory for valuable design advice, and F. Brown (U. of W.) for advice and contributions of the sputter gun and sublimation pump. PNC/XOR facilities at the Advanced Photon Source, and research at these facilities, are supported by the US Department of Energy - Basic Energy Sciences, a major facilities access grant from NSERC, the University of Washington, Simon Fraser University, the Pacific Northwest National Laboratory and the Advanced Photon Source. Use of the Advanced Photon Source is also supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. W-31-109-Eng-38.

**Abstract**
- 	An end-station for in-situ characterization of thin films at the PNC/XOR undulator beamline, Sector 20 of the Advanced Photon Source, is detailed. The ability to study films in-situ on a beamline enables examination of surfaces and interfaces on freshly-prepared films, without the influence of a capping layer. The MBE1 molecular beam epitaxy system was designed with this in mind. Now in routine operation and available for General Users on a collaborative basis, the primary function of MBE1 is to undertake polarization-dependent XAFS studies on fresh or stored films, but it also has the capability to do X-ray Standing Wave and Reflectivity measurements. The characteristics of the MBE1 system - its ranges of motions and detector options - are described in detail, with example data illustrating its functionality

- R.A. Gordon, E.D. Crozier, D.-T. Jiang1, J. Shoults, B. Barg2 and P.S. Budnik
- Department of Physics, Simon Fraser University, Burnaby, BC, Canada   V5A 1S6
- 1 Dept. of Physics, U. of Guelph, Guelph, Ontario, Canada      2 Australian Synchrotron. 800 Blackburn Rd, Clayton VIC 3168, Australia

**THE MBE1 SYSTEM**
- MBE1 exists to perform *in-situ* X-ray investigations of epitaxially-grown thin films using the techniques of Surface XAFS, X-ray Standing Wave and small angle Reflectivity under UHV conditions. Primarily intended for deposition of metal films1,3 on metal or semi-conductor substrates, the system can also be used for mineral surfaces or other *in-situ* surface studies.

**The Core of the System**

- Orientations from grazing angle to normal incidence for surface XAFS studies, small-angle/30°/Back-reflection X-ray Standing Wave measurements or Reflectivity up to 7o angle, with X-ray polarization in or out of the plane of the sample.

- Custom Sample Positioning based on the GB-16 Goniometer from Thermionics:
- 3 Translations                3 Rotations
- Heating to 800°C           Cooling to -110°C

**Options for Fluorescence Detection**

- 7-element Ge(Li) solid state detector
- Fluorescence
- Ionization chamber
- Cyberstar Detector

**XAFS, Reflectivity and X-ray Standing Wave Capabilities**

- Example data taken in-situ in the MBE1 system. XAFS measurements (left) were made at 2/3 the critical angle illustrated in the reflectivity (middle, upper right).

**Summary**
- The MBE1 end-station is a versatile surface science facility located at the PNC/XOR beamline, Sector 20 of the Advanced Photon Source. It possesses the ability to prepare and examine thin films and surfaces in-situ using the methods of XAFS, XSW and Reflectivity.  The system is available for General Users on a collaborative basis.

- Operations
- The entire system was assembled on a custom table with vertical and horizontal travel and tilt capability for positioning in the X-ray beam with or without a toroidal mirror in use. MBE1 is situated in the last hutch on the 20-ID undulator beamline at the APS. With appropriate scheduling, samples can be prepared in advance without interfering with experiments being conducted in a hutch upstream.