X-ray sensors

Zeelta X-ray sensors are monolithic pixelated HR-GaAs:Cr sensors. Each absorbed photon creates a charge proportional to its energy, which is collected by a single pixel and read out by an ASIC. The detector counts photons and sorts them by energy.

Key characteristics

Conversion: Direct, semiconductor
Detection mode: Photon counting with energy discrimination
Pixel pitch: From 35 µm
Density resolution: About 4,000 grey levels per energy channel
Interface: Metal contacts for flip-chip bonding to a photon-counting readout ASIC
Lifetime: Long service life thanks to high radiation resistance

Sensor structure: high-resistivity HR-GaAs:Cr layer with an aluminium contact, flip-chip bonded to a readout chip (ASIC). Each pixel is a single cell.

How it works

A bias voltage separates the charges created by an X-ray photon. Positive charges drift to a single electrode, so the coordinate of the event is defined unambiguously and the amount of charge gives the photon energy. Two close events are recorded separately.

Compared with scintillators

In a scintillator detector, light spreads over several photocells. That limits spatial resolution and makes it impossible to measure photon energy. Direct conversion removes that limit: detective quantum efficiency rises from about 35 to 40% to above 90%.

Advantages

Spectral (colour) imaging: element composition in addition to structure
High sensitivity, enabling lower X-ray dose for living specimens
Spatial resolution matching the pixel pitch
Sizes made to order for system integrators

Talk to us

We discuss samples, specifications and joint projects individually. Send a request or write to vvv@zeelta.com.

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