Luminescence Properties and Morphology of ZnSe:Te Films

High-speed imaging applications, such as time-resolved X-ray diffraction, require detectors with high frame rates ranging from hundreds to thousands of frames per second. New high-resolution CCD imagers capable of operating at the required frame rates have been developed; however, the current X-ray to light converters are the performance limiting factor in such applications. Here we report on the development of a structured ZnSe:Te scintillator that promises to provide extraordinarily high scintillation efficiency, emission at 640 nm (ideally suited for CCD sensors), high density of 5.4 g/cm³, and a fast decay time of ~3 mus to ~50 mus with no afterglow, which permits high speed imaging without the problem of ghosting due to persistence. Furthermore, the non-hygroscopic and non-toxic nature of the ZnSe:Te scintillator, along with its stability of response over a wide range of temperatures and extremely high levels of radiation, makes it an ideal material for radiation detection in general and for synchrotron applications in particular. At RMD, we have fabricated microcolumnar ZnSe:Te films measuring ~25 mum to 85 mum in thickness using co-evaporation of ZnSe and ZnTe on suitable substrates. These films show columnar structure with columns ranging from 0.2 mum to 5 mum in diameter. The scintillation light produced by the radiation interaction is channeled within the microcolumns by the mechanism of total internal reflection, thereby providing very high spatial resolution, even when films are made thick to achieve high X-ray absorption.