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First-Surface Scintillator for Low Accelerating Voltage Scanning Electron Microscopy (SEM) Imaging

Published online by Cambridge University Press:  18 October 2018

Marian B. Tzolov ,
Nicholas C. Barbi ,
Christopher T. Bowser  and
Owen Healy
Marian B. Tzolov*
Affiliation:
Department of Physics, Lock Haven University of PA, Lock Haven, PA 17745, USA
Nicholas C. Barbi
Affiliation:
ON Science LLC, 5616 Palm Aire Drive, Sarasota, FL 34243, USA
Christopher T. Bowser
Affiliation:
Department of Physics, Lock Haven University of PA, Lock Haven, PA 17745, USA
Owen Healy
Affiliation:
ON Science LLC, 5616 Palm Aire Drive, Sarasota, FL 34243, USA
*
Author for correspondence: Marian B. Tzolov, E-mail: mtzolov@lockhaven.edu
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Abstract

Highly luminescent thin films of zinc tungstate (ZT) have been deposited on top of conventional scintillators (Yttrium Aluminum Perovskite, Yttrium Aluminum Garnet) for electron detection in order to replace the need for a top conducting layer, such as indium tin oxide (ITO) or aluminum, which is non-scintillating and electron absorbing. Such conventional conducting layers serve the single purpose of eliminating electrical charge build-up on the scintillator. The ZT film also eliminates charging, which has been verified by measuring the Duane–Hunt limit and electron emission versus accelerating voltage. The luminescent nature of the ZT film ensures effective detection of low energy electrons from the very top surface of the structure ZT/scintillator, which we call “first-surface scintillator”. The cathodoluminescence has been measured directly with a photodetector and spectrally resolved at different accelerating voltages. All results demonstrate the extended range of operation of the first-surface scintillator, while the conventional scintillators with a top ITO layer decline below 5 kV and have practically no output below 2 kV. Scintillators of different types were integrated in a detection system for backscattered electrons (BSE). The quality of the image at high accelerating voltages is comparable with the conventional scintillator and commercial BSE detector, while the image quality at 1 kV from the first-surface scintillator is superior.

Keywords

SEMscintillatorlow voltage backscattered electron detectorzinc tungstatecathoduluminescence
Type
Software and Instrumentation
Information
Microscopy and Microanalysis , Volume 24 , Issue 5 , October 2018 , pp. 488 - 496
Copyright
© Microscopy Society of America 2018 

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Footnotes

†

Current address: Thermo-Fisher Scientific, Bellefonte, PA, USA.

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