Charge transport performance of high resistivity CdZnTe crystals doped with In/Al

To evaluate the charge transport properties of as-grown high resistivity CdZnTe crystals doped with In/Al, the α particle spectroscopic response was measured using an un-collimated ²⁴¹Am (5.48 MeV) radioactive source at room temperature. The electron mobility lifetime products (μτ)_e of the CdZnTe crystals were predicted by fitting plots of photo-peak position versus electrical field strength using the single carrier Hecht equation. A TOF technique was employed to evaluate the electron mobility for CdZnTe crystals. The mobility was obtained by fitting the electron drift velocities as a function of the electrical field strengths, where the drift velocities were achieved by analyzing the rise-time distributions of the voltage pulses formed by a preamplifier. A fabricated CdZnTe planar detector based on a low In concentration doped CdZnTe crystal with (μτ)_e 2.3 × 10^-3 cm²/V and μ_e 1000 cm ²/(V s), respectively, exhibits an excellent γ-ray spectral resolution of 6.4% (FWHM 3.8 keV) for an un-collimated ²⁴¹Am @ 59.54 keV isotope.