Modeling of ion beam induced charge sharing experiments for the design of high resolution position sensitive detectors

摘要

In a multi-electrode device, the motion of free charge carriers generated byionizing radiation induces currents on all the electrodes surrounding theactive region [1]. The amount of charge induced in each sensitive electrode isa function of the device geometry, the transport parameters and the generationprofile. Hence this charge sharing effect allows the signal from each sensitiveelectrode to provide information about the electrical characteristics of thedevice, as well as information on the location and the profile of eachionization track. The effectiveness of such approach was recently demonstratedin Ion Beam Induced Charge (IBIC) experiments carried out using a 2 MeV Hemicrobeam scanning over a sub-100 lm scale silicon device, where the ion strikelocation point was evaluated through a comparative analysis of the chargeinduced in two independent surface electrodes coupled to independent dataacquisition systems [2]. In this report, we show that the Monte Carlo method[3] can be efficiently exploited to simulate this IBIC experiment and to modelthe experimental data, shedding light on the role played by carrier diffusion,electronic noise and ion beam spot size on the induction of charge in thesensitive electrodes. Moreover, the Monte Carlo method shows that informationon the ion strike position can be obtained from the charge signals from thesensitive electrodes.