Improvement of X-ray response of CZT films by post-annealing

CdZnTe (CZT) epitaxial films are promising for X-ray flat panel detectors due to their ability for large area fabrication, high absorption efficiency, and excellent detective quantum efficiency (DQE). However, challenges like image lag, ghosting, and reduced DQE due to long response times and high dark currents persist. This study introduces a novel post-in-situ annealing technique to enhance CZT film sensitivity and transient response. Results show that a brief 20 s annealing treatment increased surface Zn content, raising detector resistivity from 3.5 x 109 Omega<middle dot>cm to 3.3 x 1010 Omega<middle dot>cm while reducing leakage current at high voltages. This treatment also significantly reduced surface defects, improving CZT film detectors' X-ray response time. Moreover, the electrons mobility-lifetime product (mu tau)e improved from 2.30 x 10-5 cm2/V to 2.17 x 10-4 cm2/V, indicating enhanced charge carrier dynamics crucial for high-speed X-ray detection. Notably, the X-ray response sensitivity achieved a commendable 126 mu C G-1<middle dot> cm-2 a bias of 30 V. In conclusion, in-situ annealing represents a remarkable step forward in the development of CZT technology for X-ray flat panel imaging, addressing critical issues and potentially broadening its applications in medical and industrial imaging systems.