Speaker
Description
Surface damage caused by ionizing radiation in SiO$_2$-passivated silicon particle detectors consists mainly of the accumulation of a positively charged layer along with trapped-oxide-charge and interface traps inside the oxide and close to the Si/SiO$_2$-interface. High density positive interface net charge can be detrimental to the operation of a multi-channel $n$-on-$p$ sensor since the inversion layer generated under the Si/SiO$_2$-interface can cause loss of position resolution by creating a conduction channel between the electrodes, which is typically addressed by including additional isolation implants ($p$-stop, $p$-spray) between n$^+$-electrodes. In the investigation of the radiation-induced accumulation of oxide charge and interface traps, a capacitance-voltage characterization study of n/$\gamma$ (mixed field)- and $\gamma$-irradiated Metal-Oxide-Semiconductor (MOS) capacitors showed that close agreement between measurement and simulation was possible when oxide charge density was complemented by both acceptor- and donor-type deep interface traps ($N_\textrm{it}$) with densities comparable to the oxide charges. Tuned densities show substantially higher introduction rates of $N_\textrm{it}$ in mixed-field environment than for $\gamma$-irradiations. Corresponding inter-electrode resistance ($R_\textrm{int}$) simulations of an $n$-on-$p$ sensor with tuned oxide-charge and interface-trap parameters show considerably higher $R_\textrm{int}$-levels for mixed-field irradiation as a result of the higher introduction rates of $N_\textrm{it}$, that additionally make the isolation performance independent of the presence of an isolation implant between the electrodes. The beneficial impact of radiation-induced accumulation of deep interface traps on inter-electrode isolation indicates that position sensitive $n$-on-$p$ sensors without isolation implants may be feasible in the future HEP-experiments with mixed field/particle dominated radiation environment.
| Collaboration | HGCAL |
|---|---|
| Role of Submitter | I am the presenter |
