In-Situ Photoelectron Spectroscopy for Thin Film Surface Analysis

By AZoNano

Table of Contents

Introduction - Photoelectron Spectroscopy Module
R3000 Analyzer
X-Ray Source
Ultraviolet (UV) Source
Conclusion
About VG Scienta

Introduction - Photoelectron Spectroscopy Module

VG Scienta offers electron spectrometers and photon sources that are well recognized for delivering researchers with sophisticated ARPES data. It is possible to operate the VG Scienta photoelectron spectroscopy (PES) module as part of the OFT EDGE cluster tool from VG Scienta for performing in-situ surface analysis utilizing XPS/UPS/ARPES methods. The PES module can also be operated as a stand-alone unit with a load lock.

PES module setup with load lock

R3000 Analyzer

The R3000 Analyzer from VG Scienta is a versatile analysis tool designed for making rapid PES measurements and band mapping. It is equipped with a sophisticated fire wire CCD camera detection system for easy upgrading and high data transfer. Ultra stable conditions are ensured by the high voltage electronics of the system for accurate and reliable measurements. It is possible to operate the analyzer in ‘Quick Mode’ that allows recording of a spectrum within seconds by getting a snap shot of the detector image and covering 12% of the pass energy. The module has a smaller footprint and the unit is placed inside an advanced mu-metal vessel.

The R3000 unit is a 135 mm mean radius hemispherical electron analyzer that is equipped with wide angle acceptance lens to provide high throughput measurements. The analyzer also features six interchangeable slits to get optimal balance between best energy resolution and best intensity. The standard slit selection includes: 0.2c, 0.4c, 0.8c, 1.3s, 3s and 0.2s, where s=straight slit and c=curved slit. The analyzer also has electronic analyzer lens X,Y deflectors and a real time read-out for experiment and diagnostics optimization applications. It also includes a -D low noise digital CCD-MCP detector system (1300 x 1000 pixel) with < 0.01 cps/channel noise level and USB connection to system computer.

X-Ray Source

A high-intensity monochromatic X-ray source is a critical element in a productive XPS system. The MX 650 X-ray source from VG Scienta generates monochromatic Al Kα radiation with high intensity. It has a quartz crystal monochromator and an aluminum anode, and delivers 1486.7 eV of excitation energy in a narrow band of 0.2 eV. The X-rays are generated when the water-cooled aluminum anode is bombarded by a fine-focused electron beam emitted from a tungsten cathode.

The projection of the electron spot on the anode surface covers an area of 1 x 3 mm2, matching the size of the X-ray spot directed on the sample by the monochromator. This spot size is akin to the dimensions of the entrance slits of the VG Scienta electron analyzers, thus enabling XPS measurements that employ the high transmission of the spectrometers.

Ultraviolet (UV) Source

The excitation source is equally important like the energy analyzer for performing efficient ARPES and UPS measurements. The VUV5000 from VG Scienta is a narrow bandwidth extreme UV source with high intensity. It emits radiation concentrated to HeI (21 eV and 23 eV) and HeII (41 eV). The flux density per unit wavelength interval is akin to that from the superior undulator beam lines. The emission of the photon flux through a 2 mm θ aperture is roughly 500 folds higher when compared to that obtainable from traditional discharge VUV sources.

The Scienta VUV5000 demonstrates remarkable stability, which makes it suitable for measurements such as analyses of nano-materials and ultra thin films, which demand long measurement times and very high intensity. Moreover, the 1 meV bandwidth enables cluster measurements and high-resolution gas phase. The VUV5040 from VG Scienta is a monochromator that is designed for high efficiency at both HeI and HeII. When used along with the high-intensity Scienta VUV5000 light source, 1 meV bandwidth and a complete separation of Helα and Helα are achieved.

Conclusion

The combination of the R3000 analyzer and high flux monochromated UV and X-ray sources offered by VG Scienta enables efficient depth profiling, elemental analysis, and insight into chemical bonding of interface layers. The robust combination of XPS/UPS/ARPES methods provides information about the electronic structure and chemistry of the material under development.

About VG Scienta

VG Scienta is the merger of the former Vacuum Generators and Gammadata Scienta businesses. By combining the expertise and knowledge from both companies VG Scienta is uniquely suited to meet the current and future needs of our customers.

Established in 1964, VG Scienta’s vacuum component business (formerly Vacuum Generators) built a name for itself based on high quality and technical innovation in UHV applications. VG Scienta continues to pioneer and innovate to go beyond the high standards demanded by the vacuum market. This has led to opportunities in semiconductor, surface science and synchrotron applications, maintaining the company’s position at the forefront of ultra high vacuum (UHV) technology.

This information has been sourced, reviewed and adapted from materials provided by VG Scienta.

For more information on this source, please visit VG Scienta.

Date Added: May 8, 2013 | Updated: Jun 11, 2013
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