A novel CdTe/CZT epitaxial technology for large area RT 1-100 keV X-ray photon detectors

We report on an innovative vapor phase epitaxial (VPE) technology for the growth of thick (i.e., up to several hundreds micron) CdTe and CdZnTe single crystal layers. The aim of this technology is to achieve the fabrication of large area X-ray detector arrays for operation in the 1-100 keV photon energy range. The new VPE method is a modification of the H₂-transport VPE (H₂T-VPE) technique previously developed in the authors laboratory for CdTe. These early growth experiments, besides showing the potentials of the method, allowed to identify critical parameters of the H₂T-VPE process, and its limitations. The new VPE method proposed here is based on the combination of metalorganic-VPE and H₂ reduction of solid CdTe to obtain the chemical transport of CdTe/CZT constituent elements into a hot-wall VPE reactor. Controlled and reproducible addition of dopant elements to the vapor can be similarly achieved for the in-situ (i.e. during growth) intentional doping/compensation of the epitaxial layers. Such technology is currently under testing using an ad-hoc designed and built reactor prototype, whose main characteristics are also described.