Thin Film CdZnTe Detector Arrays for Digital Mammography
Abstract
The objective of this program has been to develop large-area, flat-panel detectors for digital mammography using CdTe or CdZnTe deposited directly on thin-film transistor (TFT) active matrix arrays for image readout. CdTe and CdZnTe have the potential to meet the requirements for digital mammography because they have high X-ray absorption, large bandgap, and high resistivity. Activities during the second year were directed principally toward the optimization of physical and electrical properties of MOCVD-deposited CdTe and CdZnTe, and improved understanding of the CdS/Cd(Zn)Te heterojunctions used to reduce the leakage currents. By planarizing the growth susceptor, improved film morphology was realized. Studies of growth rate vs. temperature showed that reasonable growth rates could be obtained at temperatures as low as 250 deg C using readily-available precursors. Films of CdZnTe were obtained by incorporation of a Zn precursor into the growth chamber. Electrical characterization of the films continued; however, leakage currents are still too high in spite of a CdS-based heterostructure. It is not certain whether these currents are due to film purity or grain boundary effects, but it is imperative that this problem be solved before the program embarks on deposition of films onto active device structures. Film improvement will therefore be the primary focus for the coming year.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1998
- Accession Number
- ADA366608
Entities
People
- Harvey B. Serreze