http://arxiv.org/abs/2204.13099
An array of DEPFET pixels is one of several concepts to implement an active pixel sensor. Similar to PNCCD and SDD detectors, the typically $450~\mu\text{m}$ thick silicon sensor is fully depleted by the principle of sideward depletion. They have furthermore in common to be back-illuminated detectors, which allows for ultra-thin and homogeneous photon entrance windows. This enables relatively high quantum efficiencies at low energies and close to $100\%$ for photon energies between $1~\text{keV}$ and $10~\text{keV}$. Steering of the DEPFET sensor is enabled by a so-called Switcher ASIC and readout is performed by e.g. a VERITAS ASIC. The configuration enables a readout time of a few microseconds per row. This results in full frame readout times of a few milliseconds for a $512 \times 512$ pixel array in a rolling shutter mode. The read noise is then typically three electrons equivalent noise charge RMS. DEPFET detectors can be applied in particular for spectroscopy in the energy band from $0.2~\text{keV}$ to $20~\text{keV}$. For example, an energy resolution of about $130~\text{eV}~\text{FWHM}$ is achieved at an energy of $6~\text{keV}$ which is close to the theoretical limit given by Fano noise. Pixel sizes of a few tens of microns up to a centimetre are feasible by the DEPFET concept.
N. Meidinger and J. Müller-Seidlitz
Thu, 28 Apr 22
16/70
Comments: Invited chapter for the “Handbook of X-ray and Gamma-ray Astrophysics” (Eds. C. Bambi and A. Santangelo, Springer Singapore, 2022)