Design and Implementation of a High Resolution CMOS X-Ray Imager with Amorphous Selenium Sensor

Abstract

This thesis presents a novel system for high resolution X-ray imaging in medical and industrial applications. Complementary metal-oxide-semiconductor (CMOS) technology is a standard technology used in most state of the art electronic systems including imagers. In addition, amorphous selenium (a-Se) is a photoconductor that is sensitive to a wide range of X-ray photon energies.

Increasing the e ective spatial resolution is one the primary goals of state of the art imaging systems. The objective of this thesis is to integrate the a-Se sensor and CMOS readout to make an ultra high resolution X-ray imager. Other features of the imager like noise, dynamic range, imaging speed, and ll factor are competitive with existing X-ray imaging systems. All of the signal reading circuitry is implemented on a custom CMOS chip and the a-Se sensor is deposited on top of it through post processing. This thesis also describe the design of external hardware and software needed to properly operate the imager.

We demonstrate our imager with a 64 × 64 pixel array prototype containing 5.6 × 6.25 μm2 and 11.2 × 6.25 μm2 pixel. Our results include characterization of the electronic and X-ray imaging performance of our system. We also show X-ray images with e ective resolution down to 14 μm.