Charge collection efficiency mapping of a Frisch-collared BiI3 device

Charge collection efficiency (CCE) mapping was performed by simulating a 5.0 × 5.0 × 10.0 mm³ Frisch-collared BiI₃ gamma-ray detector with an applied bias of 4800V and comparing the results to those previously published for a 4.7 × 4.7 × 9.5 mm³ Frisch-collared CdZnTe device with an applied bias of 1200V. The BiI₃ mobility-lifetime products used for CCE mapping were μ_eτ_e = 9.5 × 10^-6 cm² V^-1 and μ_hτ_h = 1.0 × 10^-7 cm² V^-1 for electrons and holes, respectively. The simulations were performed using the modified form of the Hecht equation and the necessary weighting-potential and weighting-field distributions were simulated using the commercially available software package COULOMB©. After comparing the simulation results to CdZnTe, the applied bias and mobility-lifetime products were adjusted separately until the Frisch-collared BiI₃ device resembled the CCE of the CdZnTe Frisch-collared device. Using the previously stated mobility-lifetime products, an applied bias of 2.1 MV is necessary to achieve similar CCE as that of CdZnTe at 1200V. Likewise, an improvement of three orders of magnitude (μ_eτ_e = 9.5 × 10^-3 cm² V^-1 and μ_hτ_h = 1.0 × 10^-4 cm² V^-1) to the BiI₃ mobility-lifetime products is required to operate the device at an applied bias of 4800V and approximately match the CCE of CdZnTe at 1200V.