Inorganic Semiconductor Films
High Z, dense, wide band gap, inorganic semiconductor films are important for high resolution x-ray imaging systems. The films convert incident x-ray flux into an electronic image. Advantages of this “direct conversion” approach include high spatial resolution and high gain. RMD is actively developing films for next generation imaging systems for medical and materials science applications. Films have been deposited by physical vapor transport and screen printing methods. Materials include mercuric iodide (HgI2), lead iodide (PbI2).and thallium bromide (TlBr).Imaging devices have been fabricated by depositing films on readout devices such as amorphous silicon thin film transistor (a-Si TFT) arrays and vidicon tube targets.
Scanning electron micrograph of a TlBr film deposited by physical vapor deposition method.
The above image shows a scanning electron micrograph of a TlBr film deposited by physical vapor deposition. Figure 8 shows a HgI2 film deposited on an ITO-coated glass substrate (left) and an x-ray imaging device consisting of an amorphous silicon thin film transistor array coated with HgI2 (right). Images recorded with this device are shown below.
Screen printed HgI2 film on ITO-coated glass substrate (left) and HgI2 – coated a-Si TFT array (right).
Image of line pair phantom (left) and section of foot phantom (right) acquired with a HgI2 -coated a-Si TFT array.