Development and testing of a radiation-hard large-electrode DMAPS design in a 150 nm CMOS process
Résumé
The LF-Monopix chips are depleted monolithic active pixel sensors that follow the large-electrode design approach and implement a fast synchronous read-out architecture. They are designed in a 150 nm CMOS process and make use of large voltages () and highly resistive substrates () to collect charge through drift and enhance their radiation hardness. Samples of the first prototype (“LF-Monopix1”) with a thickness of were irradiated to assess the tolerance of the chip’s substrate and front-end circuitry to the surface and bulk damage doses expected at modern collider experiments. The device remained fully operational, with only a very small gain degradation and an increase in noise by less than after a total ionizing dose of . Efficiency measurements in a sample exposed to a neutron fluence of showed that at least of all minimum ionizing particles going through a fully depleted detector are recorded in less than . In the latest design (“LF-Monopix2”) the column length was tripled and the pixel pitch reduced by with respect to its predecessor. The chip was successfully thinned down while keeping its breakdown voltage above and achieving a front-end threshold dispersion of after tuning.