TKD in SEM - EBSD Detector Optimized for Transmission Kikuchi Diffraction (t-EBSD)

The OPTIMUS™ TKD detector head, developed specifically to optimize the geometry between the sample and detector for on-axis Transmission Kikuchi Diffraction analysis (TKD) in SEM, can now be fitted onto Bruker Nano Analytics’ high-performance eFlash EBSD detector series.

The detector head not only captures Kikuchi patterns with unrivaled sensitivitybut also SAED (Selected Area Electron Diffraction)-like patterns.

Orientation Mapping With at Least 2 nm Spatial Resolution

Positioning the horizontal phosphor screen beneath the SEM sample offers two key benefits over the more-common vertical setup:

Gnomonic projection distortions are minimized

Signal yield is increased by an order of magnitude

The substantially stronger signal enables the acquisition of orientation maps with small apertures at an enhanced spatial resolution. When using a high-end FE-SEM, an effective spatial resolution of 2 nm or better can be achieved on a wide range of different types of samples (alternatively we could use “…wide range of materials”.

The QUANTAX EBSD system can also work at acceleration voltages as low as 5 kV. This helps in lowering the mean free path and thus increasing the yield of the Kikuchi diffraction signal. This comes in handy for examining thin and “lightweight” samples.

Distortions induced by gnomonic projection are a major problem in EBSD. The OPTIMUS™ 2 TKD detector head avoids this problem by precisely matching the phosphor screen center with the pattern center, resulting in an ideal geometry that is better than standard EBSD geometry. The resultant Kikuchi patterns have minimal distortions, greatly improving band recognition and indexing.

ARGUS™ FSE Imaging System

ARGUS™ imaging technology offers spectacular Dark and Bright Field imaging with details down to the nanoscale scale, thereby changing the SEM into a “low-kV TEM.”

Individual dislocations and networks of dislocation walls in deformed materials can be visualized using ARGUS™. The Dark Field-like images display 3D information on the position and inclination of the boundary plane.

Ease of Use

The OPTIMUS™ TKD detector head can be attached to any existing eFlash detector replacing the standard EBSD detector head. A trained user can complete the system set-up in less than 15 minutes – meaning swapping between EBSD and TKD modes can be done quickly whenever necessary.

The OPTIMUS™ TKD incorporates Bruker’s innovative collision safety system: in the unlikely case of a collision, the detector retracts at a speed of 10 mm/s, reducing any potential damage to the equipment.

Bruker’s OPTIMUS™ Detector Head for TKD in SEM

OPTIMUS Sample Holder (Top View)OPTIMUS Sic Phase MapOPTIMUS (side view)Detail of raw orientation map without data cleaning. It shows annealing twin domains in fcc crystals just 6 to 9 nm wide.Color coded dark field image acquired from a heavily deformed pure AI sample. The insert shows individual dislocations.Color coded dark field image acquired from a heavily deformed pure (ARB) AI sample. The highlighted area shows 3D details. The position and inclination of the boundary plane between grains is visible through the sample thickness.Pattern quality map and corresponding raw orientation map acquired at 100 fps with a 4 nm step size from a FIB prepared AU sample using ~ 0.6 nA probe current and 28 kV EHT. The effective spatial resolution is at least 3 nm.Color coded dark field image acquired from FIB prepared SiC sample. The image depicts a heavily twinned microstructure with some twins being less than 10 nm wide.