Spiral Biasing Adaptor for Drift Detectors and Arrays
Bias is applied to silicon drift detectors (SDDs) to force electrons to drift toward the anode. A spiral SDD is a special type of SDD detector that utilizes a cylindrical geometry. Its smaller anode has lower capacitance and therefore less sensitivity to electronic noise, improving resolution. In spiral SDDs, ion implants are required as both the rectifying junction and a voltage divider that creates the potential field forcing the electrons to drift toward the anode. Coupling these two functions together constrains the ratio of spiral width to pitch for a uniform drift field in the drift channel, which results in a large current for a given voltage difference between the start and end of the spiral. In addition, the heat generated within the spiral stays with the SDD. Most importantly for a spiral SDD array, the power consumption can be substantial, approaching watts.
Here we describe a low-current biasing adaptor customizable for any desired geometry of the drift detector single cell with minimum drift time of carriers. The biasing adaptor has spiral shaped ion-implants that generate the desired voltage profile. The biasing adaptor can be processed on the same wafer as the drift detector array, and only one biasing adaptor chip/side is needed for one drift detector array to generate the voltage profiles on the front and back sides of the detector array.
This invention comprises a new design for spiral biasing adaptors (SBA) for use in silicon drift detectors (SDD) and SDD arrays. The new SBA design comprises optimized spiral pitch and width parameters as well as separating the SBA from the SDD junction. Optimized pitch and width parameters for the spiral design can provide improved current and electric field characteristics and improve electron cloud drift time in SDDs by more than a microsecond. By removing the SBA from the SDD junction, and operating the SBA as a device external to the SDD array elements, improved current, heat, and power performance is achieved. Finally, a new SDD array can be realized by appropriately interconnecting the concentric rings of the SDD array elements with each other and with at least one external SBA.Benefits
Compared to other X-ray detectors, Silicon Drift Detectors (SDDs) and SDD arrays convey advantages, including higher count rates and faster processing, higher energy resolution, faster speed and lower dead time, and less strict cooling requirements (only Peltier cooling is required). This SBA technology improves conventional SDDs and SDD arrays by requiring less power, improving thermal dissipation, and providing for manufacturing simplicity.Applications and Industries
For use in X-ray spectroscopy, including X-ray Fluorescence (XRF), X-ray Absorption Spectroscopy (XAS), and Energy Dispersive X-ray Spectroscopy (EDS), and electron microscopy (EDX), including scanning electron microscopy (SEM) and scanning-tunneling electron microscopy (STEM). Industries that use X-ray spectroscopy include: Automotive, Battery, Biotechnology, Chemical, Electronics, Fuel cells, Mining, Nanotechnology, Nuclear, Packaging, Paper and wood, Polymer and plastic, Semiconductor, Steel, and Textiles, among others.More Information
WO 2013/063032 published on May 2, 2013Technology Status
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