Lead iodide films for X-ray imaging

This paper discusses the X-ray detection and imaging characteristics of a new semiconductor material, lead iodide (Pbl(2)), when prepared in form of a vapor deposited film for use in digital imaging. Lead iodide is a wide bandgap semiconductor (E-g = 2.3 eV) and provides direct conversion of X-ray energy into electrical charges. This provides higher signal amplitude than conventional systems using scintillation or phosphor screens since only about 5 eV is required to form a charge pair in lead iodide as opposed to more than 30 eV in case of phosphors to produce optical photons. Furthermore due to very little lateral diffusion of charge pairs, high spatial resolution can be obtained with such direct conversion films. Finally, due to low dark current in these films, the electronic noise in the films is also very low. In this paper we discuss the lead iodide film preparation procedure, its electronic properties such as resistivity and charge transport, its signal amplitude, and its X-ray imaging performance.