Charge collection properties of a depleted monolithic active pixel sensor using a HV-SOI process

New pixel detector concepts, based on commercial high voltage and/or high resistivity CMOS processes, are being investigated as a possible candidate to the inner and outer layers of the ATLAS Inner Tracker in the HL-LHC upgrade. A depleted monolithic active pixel sensor on thick film SOI technology is being extensively investigated for that purpose. This particular technology provides a double well structure, which shields the thin gate oxide transistors from the Buried Oxide (BOX). In addition, the distance between transistors and BOX is one order of magnitude bigger than conventional SOI technologies, making the technology promising against its main limitations, as radiation hardness or back gate effects. Its radiation hardness to Total Ionizing Dose (TID) and the absence of back gate effect up to 700 Mrad has been measured and published [1]. The process allows the use of high voltages (up to 300V) which are used to partially deplete the substrate. The process allows fabrication in higher resistivity, therefore a fully depleted substrate could be achieved after thinning. This article shows the results on charge collection properties of the silicon bulk below the BOX by different techniques, in a laboratory with radioactive sources and by edge Transient Current Technique, for unirradiated and irradiated samples.