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4-Channel-aSTEM DetectorDetecting Transmitted Electrons in an FESEM with the new Annular STEM Detector

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Contact: Dr. Ulrich Kohl-Roscher

Date: October 2015

Introduction

Usually, a Field Emission Scanning Electron Microscope

(FESEM) is used to image the surface structures or

near-surface structures of a specimen. However, with the

optional Scanning Transmission Electron Microscope (STEM)

detector, you can detect transmitted electrons as well.

Specimens need to be ultra thin, so they can be penetrated

easily by the electron beam.

Due to resolving power of the GEMINI column and the

included 12x sample holder you save processing time on

TEM samples for high resolution applications.

The diode geometry is optimized to the axially symmetric

scattering behavior of electrons in STEM mode and

provides improved low kV response and higher sensitivity.

The increased detector area allows larger acceptance angles.

Bright field (BF) and dark field (DF) signals can be clearly

separated. Electrons scattered at higher angles will be

detected by the annular dark field (ADF) or the high angle

annular dark field (HAADF) segment. An arbitrary configura-

tion of segments for read out can be defined by the user.

Due to the new electronics the 4-Channel-aSTEM Detector

allows a parallel read out of up to four different signal

combinations. This not only saves time but also reduces

beam damage on the sample to a minimum since different

sample information can be obtained in a single scan run.

4-Channel-aSTEM Detector Detecting Transmitted Electrons in an FESEM with the new Annular STEM Detector

Availability

The 4-Channel-aSTEM Detector is available for the following

microscopes:

• Crossbeam series

• GeminiSEM series

• MERLIN series

Benefits

• High speed 4 channel parallel read out

• Higher sensitivity

• Better signal to noise ratio (S/N)

• Larger diode active area, larger acceptance angle

• Improved low kV response

• High sample throughput

• Reduced radiation damage on specimen

Minimized sample damage by simultaneous acquisition of

up to 4 different detector configurations during a single

scan.

• Imaging of stained and unstained samples

• New annular detector design

Optimized for better adaptation to the scattering behavior

of electrons in STEM mode. BF, DF and HAADF signals can

be clearly separated. By inverting two of the DF segments

oriented dark field imaging is possible.

• Easy to use

The aSTEM detector is fully software-controlled.

The detector is inserted and retracted pneumatically.

• Arbitrary segment configurations can be defined and read

out.

Several different STEM Modes acquired simultaneously from one Detector.

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Specification

Feature Specification

Imaging modes Bright-field, Dark-field and

orientated Dark-field

Image processing Real-time Mixing, Normal, Inverse

WD detector 8 mm +/-1 mm

WD sample 2 - 5 mm

Detector assembly Fully retractable

Sample holder 12 TEM grids on carrousel

included

Upgrade path

Software SmartSEM 5.07

Hardware NSE systems

Firmware SmartSEM 5.07 release

The product requires a free port. The old port of an already

existing STEM detector can not be reutilized. Due to the

bigger diode head, a new port is required.

Please state the desired port when ordering.

A system preventive maintenance performed within the last

12 months is mandatory.

The retrofit must be performed by a ZEISS-authorized

service engineer. Application training is

recommended. For further information, contact:

microscopy@zeiss.com

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• Allows to obtain SEM images of conventionally stained

and prepared TEM samples (UD sections of plastic

embedded samples) in TEM like quality.

• STEM mode EDX resolution down to 20 nm or less

• Improved graphical user interface in SmartSEM

Operation

The semiconductor based detector consists of multiple seg-

ments: a BF area in the middle, four DF diode segments,

an additional ADF ring and a dedicated HAADF outer ring

(see fig. 1). Among the four dark field segments, the two

opposing fields are pairwise connected. The total detec-

tor area is 200 mm² which corresponds to an acceptance

angle of up to one rad at minimal detector sample dis-

tance. Operation of the

GEMINI Multi-Mode aSTEM detection system and signal

processing is controlled by an additional menu embedded

into the SmartSEM graphical user interface.

Figure 1

Figure 2

Schema of the semiconductor based detector with its BF area in the center, the four DF diodes, the ADF ring and the HAADF outer ring.

D2D1

BF

DF1DF2

ADF

HAADF

Comparison of the old and the new detector.

Upgrade Info

Part Ordering no.

Upgrade Kit for pneumatically driven

aSTEM detector, long version

349506-9015-991

Upgrade Kit for pneumatically driven

aSTEM detector, short version

349506-9015-990

Universal Port Adapter for MERLIN 347805-8024-200

66mm MP Port Adapter for MERLIN 347805-8027-100

CL/C port adapter for MERLIN 347805-8017-200

EBSD Port Adapter for

MERLIN & Crossbeam

347805-8018-100

Universal Port Adapter for

Crossbeam

347805-8029-100

66 MP Port Adapter for Crossbeam 347805-8020-200

GIS Port Adapter for Crossbeam 347805-8026-200

Figure 3

Figure 4

Heart muscle, mouse, ultrathin section, ultramicrotome, on grid, SEM, aSTEM, BF image. Courtesy of M. Kruger, Institute for Anatomy, University Leipzig, Germany

Mouse brain, ultrathin section on a grid, double membrane of mito-chondria resolved down to lipid bilayer structure. Left: annular STEM (aSTEM) BF, Right: aSTEM DF. Sample: courtesy of EPFL Lausanne, Switzerland

Carl Zeiss Microscopy GmbH 07745 Jena, Germany microscopy@zeiss.com www.zeiss.com/microscopy

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