The XFlash® FlatQUAD, the core of QUANTAX FlatQUAD, is based on a novel detector concept. This includes positioning the detector from the side between pole piece and sample. Therefore, the detector is mounted on a horizontal port on the SEM chamber. Conventional detectors, which rarely extend beneath the pole piece require an inclined port. To ensure compatibility with many different SEM types, the detector can be precisely positioned in X, Y and Z direction.
The four independent silicon drift detector chips of the XFlash® FlatQUAD are in an annular arrangement around a hole in the detector module. The primary electron beam passes through this opening. This design, as well as the intention to keep the detector finger as thin as possible, require a new method to prevent backscattered electrons from reaching the detector chips. The detector is equipped with special polymer windows of varying thickness. They absorb the backscattered electrons while allowing X-rays to pass through. The polymer windows are mounted in a slider which permits changing them without affecting the vacuum. This enables SEM acceleration voltage changes while the detector is in measurement position.
The position and size (4 × 15 mm2 active area) of the detector chips provide the largest solid angle for X-ray collection in a SEM. Depending on the specific geometrical conditions more than 1 sr is possible in combination with a high take-off angle of 60° or more. The collection efficiency can lead to extremely high count rates. All four detector chips are therefore equipped with separate signal processing channels. This allows input count rates (ICR) of up to 4,000,000 cps and a combined output count rate (OCR) of up to 1,600,000 cps. The XFlash® FlatQUAD provides an excellent energy resolution of 126 eV at Mn Kα and 100,000 cps input count rate (51 eV at C K and 60 eV at F K). Resolution classes of 129 eV and 133 eV are also available.