(oral talk) Dead-Layer-Free Semiconductor Detectors via Highly Charged Dielectrics

The entrance window of semiconductor particle detectors typically contains undepleted regions that the impinging particles pass through before reaching the sensitive area of the device. These so-called dead layers pose a fundamental limitation for achievable energy resolutions and are unavoidable in externally doped pn-junction detectors. Here, we fabricate a silicon particle detector using an alternative method for creating the charge-collecting junction that depletes the whole surface and minimizes the dead layer. The junction is realized by inducing an electric field at the surface of the detector using a charged thin film, which consequently forms an inversion layer. Such approach has previously been implemented in photodiodes, which have demonstrated efficient collection of charge carriers from the very surface of the devices. Utilizing the same method in a particle detector could thus allow a device without junction-originated dead layer. Our device is characterized using detection of alpha particles as a case example. We achieve energy resolutions and leakage currents that are, already without extensive device optimization, on the same level with commercial externally doped silicon particle detectors. We also demonstrate the excellent charge collection capability extending all the way to the device surface. Finally, we discuss the applicability of the device in detection of other charged particles in addition to alpha particles, which may benefit from the design even more.