Towards 3D Integration of Monolithic X or Γ Ray Detectors Under Possible Electromagnetic Perturbations or Malfunctions

Abstract

In this paper, X/Γ rays photodetectors are designed using a proposed set of CAD oriented tools. These tools are handled to study not only the device behavior, but also its possible drawbacks. First of all, we develop an efficient time-domain electromagnetic wave simulator for modeling a PiN diode in a micro-wave circuit. In fact, both the active semiconductor devices and passive interconnection domains are introduced. They combine accurate modeling of the transport phenomena in the diode and electromagnetic wave effects present around the device. A "leapfrog" algorithm of a 3-D FDTD method, the spurious waves coming from any direction, is used for the simulation of Si-PiN and CCD cells. This physical method is powerful as it can give, starting from microscopic phenomena, the scattering parameters, after some FFT’s, tools very useful for the engineers. The obtained results are in agreement with those from other commercial simulators and also in agreement with theoretical concepts. A 2D numerical simulation of space charge under X-ray irradiation, in a CdTe phodetector, is investigated. It provides important information on the distribution and the dynamics of the electric phenomena of the detector; it is the first time, up to our knowledge, that an electrical field-induced parasitic space charge is described with simulations. We think that some experiment, based on some linear electro-optic effect - Pockels effect - could confirm these results. This local charge collection properties can be also accessed by performing IR pulsed laser experiments. Finally, some fast transimpedance amplifier has been designed in a quarter micron technology. The architecture has been adapted to the characteristics of the technology through a careful optimization of the design, resulting in an extremely fast amplifier, with fall time near 1 ns at room temperature.