Radiation Tolerance of SiGe BiCMOS Monolithic Silicon Pixel Detectors without Internal Gain Layer

A monolithic silicon pixel prototype produced for the MONOLITH ERC Advanced project was irradiated with 70 MeV protons up to a fluence of 1 x 10^16 1 MeV n_eq/cm^2. The ASIC contains a matrix of hexagonal pixels with 100 {\mu}m pitch, readout by low-noise and very fast SiGe HBT frontend electronics. Wafers with 50 {\mu}m thick epilayer with a resistivity of 350 {\Omega}cm were used to produce a fully depleted sensor. Laboratory tests conducted with a 90Sr source show that the detector works satisfactorily after irradiation. The signal-to-noise ratio is not seen to change up to fluence of 6 x 10^14 n_eq /cm^2 . The signal time jitter was estimated as the ratio between the voltage noise and the signal slope at threshold. At -35 {^\circ}C, sensor bias voltage of 200 V and frontend power consumption of 0.9 W/cm^2, the time jitter of the most-probable signal amplitude was estimated to be 21 ps for proton fluence up to 6 x 10 n_eq/cm^2 and 57 ps at 1 x 10^16 n_eq/cm^2 . Increasing the sensor bias to 250 V and the analog voltage of the preamplifier from 1.8 to 2.0 V provides a time jitter of 40 ps at 1 x 10^16 n_eq/cm^2.Comment: Submitted to JINS

Radiation tolerance of SiGe BiCMOS monolithic silicon pixel detectors without internal gain layer

A monolithic silicon pixel prototype produced for theMONOLITH ERC Advanced project was irradiated with 70 MeV protons upto a fluence of 1 × 10$^{16}$1 MeV n$_{eq}$/cm$^{2}$. The ASIC contains a matrix ofhexagonal pixels with 100 μm pitch, readout by low-noise andvery fast SiGe HBT frontend electronics. Wafers with 50 μmthick epilayer with a resistivity of 350 Ωcm were used toproduce a fully depleted sensor. Laboratory tests conducted with a$^{90}$Sr source show that the detector works satisfactorily afterirradiation. The signal-to-noise ratio is not seen to change up tofluence of 6 × 10$^{14}$n$_{eq}$/cm$^{2}$. The signaltime jitter was estimated as the ratio between the voltage noise andthe signal slope at threshold. At -35°C, sensor bias voltageof 200 V and frontend power consumption of 0.9 W/cm$^{2}$, the timejitter of the most-probable signal amplitude was estimated to be σ$_{t}$$^{90}$Sr = 21 ps for proton fluence up to6 × 10$^{14}$n$_{eq}$/cm$^{2}$ and 57 ps at1 × 10$^{16}$n$_{eq}$/cm$^{2}$. Increasing the sensorbias to 250 V and the analog voltage of the preamplifier from 1.8to 2.0 V provides a time jitter of 40 ps at1 × 10$^{16}$n$_{eq}$/cm$^{2}$.A monolithic silicon pixel prototype produced for the MONOLITH ERC Advanced project was irradiated with 70 MeV protons up to a fluence of 1 x 10^16 1 MeV n_eq/cm^2. The ASIC contains a matrix of hexagonal pixels with 100 μm pitch, readout by low-noise and very fast SiGe HBT frontend electronics. Wafers with 50 μm thick epilayer with a resistivity of 350 Ωcm were used to produce a fully depleted sensor. Laboratory tests conducted with a 90Sr source show that the detector works satisfactorily after irradiation. The signal-to-noise ratio is not seen to change up to fluence of 6 x 10^14 n_eq /cm^2 . The signal time jitter was estimated as the ratio between the voltage noise and the signal slope at threshold. At -35 {^∘}C, sensor bias voltage of 200 V and frontend power consumption of 0.9 W/cm^2, the time jitter of the most-probable signal amplitude was estimated to be 21 ps for proton fluence up to 6 x 10 n_eq/cm^2 and 57 ps at 1 x 10^16 n_eq/cm^2 . Increasing the sensor bias to 250 V and the analog voltage of the preamplifier from 1.8 to 2.0 V provides a time jitter of 40 ps at 1 x 10^16 n_eq/cm^2