Active silicon detectors built on p-type substrate are a promising technological solution for large area silicon trackers such as those at the High Luminosity LHC, but the radiation hardness of this novel approach has to be evaluated. Active n-in-p strip detector prototypes CHESS2 for ATLAS with different substrate resistivities in the range of 20–1000 Ohm.cm were irradiated with neutrons and protons up to a fluence of 2e15 and 3.6e15 n_eq/cm^2. Charge collection in passive test structures on the chip was evaluated using Edge-TCT and minimum ionising electrons from 90Sr. Results were used to assess radiation hardness of the detector in the given fluence range and to determine parameters of initial acceptor removal in different substrates.
COBISS.SI-ID: 32212263
Depleted Monolithic Active Pixel Sensor (DMAPS) prototypes developed in the TowerJazz 180 nm CMOS imaging process have been designed in the context of the ATLAS upgrade Phase-II at the HL-LHC. The pixel sensors are characterized by a small collection electrode (3 µm) to minimize capacitance, a small pixel size (36.4× 36.4 µm2), and are produced on high resistivity epitaxial p-type silicon. The design targets a radiation hardness of 1E15 1 MeV neq/cm2, compatible with the outermost layer of the ATLAS ITK Pixel detector. This paper presents the results from characterization in particle beam tests of the Mini-MALTA prototype that implements a mask change or an additional implant to address the inefficiencies on the pixel edges. Results show full efficiency after a dose of 1E15 1 MeV neq/cm2.
COBISS.SI-ID: 33215783
The edge transient-current technique (Edge-TCT) and charge-collection measurements with passive test structures made with the LFoundry 150-nm CMOS process on a p-type substrate with an initial resistivity of over 3 kOhm.cm are presented. The measurements were made before and after irradiation with reactor neutrons up to 2e15 n_eq/cm^2. Two sets of devices were investigated: unthinned (700 um) with the substrate biased through the implant on top and thinned (200 um) with a processed and metallised backplane. The depletion depth was estimated with the Edge-TCT and the collected charge was measured with a 90Sr source using an external amplifier having a 25-ns shaping time. The depletion depth for a given bias voltage decreased with the increasing neutron fluence, but it was still larger than 70 um at 250 V after the highest fluence. After irradiation a much higher collected charge was measured for the thinned detectors with a processed backplane compared to the unthinned devices, although the same or an even larger depletion depth was measured in the unthinned devices. The most probable value of the collected charge of over 5000 electrons was measured with a thinned device also after irradiation to 2e15 n_eq/cm^2. This is sufficient to ensure the successful operation of these detectors at the outer layer of the pixel detector in the ATLAS experiment at the upgraded HL-LHC.
COBISS.SI-ID: 31516967