Modeling, simulation and data fitting of the charge injected diodes (CID) for SLHC tracking applications

Modeling and simulations have been performed for the charge injected diodes (CID) for the application in SLHC. MIP-induced current and charges have been calculated for segmented detectors with various radiation fluences, up to the highest SLHC fluence of 1×1016 neq/cm2. Although the main advantage of CID detectors is their virtual full depletion at any radiation fluence at a modest bias voltage (<600 V), the simulation of CID and fitting to the existing data have shown that the CID operation mode also reduces the free carrier trapping, resulting in a much higher charge collection at the SLHC fluence than that in a standard Si detector. The reduction in free carrier trapping by almost one order of magnitude is due to the fact that the CID mode also pre-fills the traps, making them neutral and not active in trapping. It has been found that, electron traps can be pre-filled by injection of electrons from the n+ contact, and hole traps can be pre-filled by injection of holes from the p+ contact. The CID mode of detector operation can be achieved by a modestly low temperature of around −40 °C, achievable by the proposed CO2 cooling for detector upgrades in SLHC. High charge collection comparable to the 3D electrode Si detectors makes the CID Si detector a valuable alternative for SLHC detectors for its much easier fabrication process.