RNDR-DEPFET detectors: deep sub-electron active pixel sensors with high time resolution

Abstract

Sensors with repetitive non-destructive readout, which achieve a deep sub-electron noise have been established for high precision applications. The Depleted P-channel Field-Effect Transistor with Repetitive Non-Destructive Readout - so-called RNDR-DEPFET - provides an active pixel sensor on a fully depleted silicon bulk with the capability to collect, store and read out charge carriers within each pixel. The readout process takes place by shifting the collected electrons between two readout nodes within one pixel in order to enable statistically independent measurements. In a conventional mode like the rolling shutter operation, the collected electrons are removed after the desired number of readings has been reached. However, the active pixel concept enables a continuous or incremental sampling of the signal during charge collection in combination with a high level of parallelization, as well. In this mode, the charge collection and readout takes places simultaneously and electrons are just removed before the storing capacity of the readout node has been exceeded. After the working principle of RNDR-DEPFET detectors has been demonstrated on a 64×64 pixel sensor, a incremental readout mode with a high time resolution of single electron events is studied. A time resolution in the order of 300 μs for single electron detection is demonstrated, which significantly improves the capabilities for background rejection and detection of rare signals. The paper concludes with an evaluation of applications for light dark matter searches and astrophysical applications.