Publication detail

The collection efficiency of the Everhart-Thornley detector of secondary electrons in SEM.

KONVALINA, I. MÜLLEROVÁ, I. FRANK, L.

Czech title

Sběrová účinnost Everhart-Thornley-ho detektoru sekundárních elektronů v REM.

English title

The collection efficiency of the Everhart-Thornley detector of secondary electrons in SEM.

Type

conference paper

Language

en

Original abstract

The Everhart-Thornley (ET) type detector is widely used in SEM for the collection of secondary electrons (SE). At first glance the electrostatic field of the front grid, biased to a positive potential of several hundred volts, might be thought to attract all SE of a kinetic energy below 50 eV or at least near the SE spectrum peak at 1 – 3 eV. However, the detection quantum efficiency (DQE) of such detectors has been found to be significantly lower than one. The DQE depends heavily on the collection efficiency (CE), i.e. the proportion of emitted species that impact on the detector. Preliminary simulations of electron trajectories indicated CE values for the ET detector even below 10 % for small working distances and more detailed results are reported here.

Czech abstract

Detektory Everhart-Thornley-ho typu se široce používají v REM pro sběr sekundárních elektronů (SE). Na první pohled se zdá, že elektrostatické pole na přední straně síťky, která je na kladném potenciálu několika set voltů, přitáhne všechny SE s energií pod 50 eV nebo aspoň s energií v blízkosti píku 1-3 eV v SE spektru. Avšak zjištěná detekční kvantová účinnost (DQE) mnoha detektorů byla výrazně menší než jedna. DQE silně závisí na sběrové účinnosti, což je procento emitovaných částic, které dopadnou na detektor. První simulace trajektorií elektronů naznačují hodnoty sběrové účinnosti ET detektoru dokonce pod 10 % při malých pracovních vzdálenostech.

English abstract

The Everhart-Thornley (ET) type detector is widely used in SEM for the collection of secondary electrons (SE). At first glance the electrostatic field of the front grid, biased to a positive potential of several hundred volts, might be thought to attract all SE of a kinetic energy below 50 eV or at least near the SE spectrum peak at 1 – 3 eV. However, the detection quantum efficiency (DQE) of such detectors has been found to be significantly lower than one. The DQE depends heavily on the collection efficiency (CE), i.e. the proportion of emitted species that impact on the detector. Preliminary simulations of electron trajectories indicated CE values for the ET detector even below 10 % for small working distances and more detailed results are reported here.

Keywords in Czech

rastrovací elektronový mikroskop, sběrová účinnost, sekundární elektrony

Keywords in English

scanning electron microscope, collection efficiency, secondary electrons

Released

22.08.2004

Location

Antwerpy

Book

EMC 2004 - Proceedings of the 13th European Microscopy Congress

Pages count

2

BIBTEX


@inproceedings{BUT21737,
  author="Ivo {Konvalina} and Ilona {Müllerová} and Luděk {Frank},
  title="The collection efficiency of the Everhart-Thornley detector of secondary electrons in SEM.",
  booktitle="EMC 2004 - Proceedings of the 13th European Microscopy Congress",
  year="2004",
  month="August",
  address="Antwerpy"
}