Sep 12 – 17, 2021
University of Birmingham
Europe/London timezone

Characterisation of the spectroscopic properties of p-type Si sensors for X-ray spectroscopy

Sep 15, 2021, 1:04 PM
Teaching and Learning Building (University of Birmingham)

Teaching and Learning Building

University of Birmingham

Edgbaston Campus University of Birmingham B15 2TT UK


Ben Cline (Science and Technology Facilities Council)


To meet the requirements of next-generation light sources, STFC has begun work on a new generation of detector technology, capable of operating at MHz frame rates. Although readout electronics are key components of these systems, the choice of sensor material is critical, with high-density semiconductors such as CdZnTe (CZT) required for higher-energy operation. Whilst high-Z materials are commonly used to measure radiation >20keV, the lower electron-hole-pair-generation energy of Si (3.62eV cf. 4.67eV for CZT) offers the potential of improved spectral resolution at lower energies. However, unlike most Si sensors, these compound semiconductors are predominately electron-readout materials. The advantage of p-type-Si sensors is that they are electron readout, meaning a single electron-sensitive readout chip may be used in the measurement of both low- and high-energy X-rays; previously, detector groups were required to design separate versions of an application-specific integrated circuit (ASIC) or operate at sub-optimal performance. Crucially, this will enable a single ASIC technology to have applications across multiple instruments at these light sources.

In this paper, results relating to the characterisation of p-type-Si sensors, each pixelated on a 76$\times$80 array of 300- or 500μm-thick material, and bonded to the STFC HEXITEC ASIC (Veale et al. 2018), are presented. Current-voltage measurements show low <165 pA mm$^{-2}$ leakage currents up to an applied bias of -120V for 500μm-thick devices, and alongside excellent charge-transport properties this results in high-resolution spectroscopic performance. Results demonstrate highly-uniform room-temperature spectroscopic resolution can be obtained across the investigated energy range with average FWHM of <0.8keV measured at 13.81keV. Results are presented alongside studies into the temporal and temperature-based stability of such devices, and the effect of applied bias on energy resolution and charge sharing.

The results presented are highly promising and suggest p-type Si may be used alongside high-Z sensors for X-ray Imaging at future light sources.

Title Mr
Nationality British
Your name Ben Cline
Institute Science and Technology Facilities Council

Primary author

Ben Cline (Science and Technology Facilities Council)


Matthew Veale (STFC Rutherford Appleton Laboratory) Matthew Wilson (STFC) Mr Mark Bullough (Micron Semiconductor Ltd.) Mr Keith Richardson (Micron Semiconductor Ltd.) Mr Hydon Thorpe (Micron Semiconductor Ltd.)

Presentation materials