Contact Formation (Hg, CD)Te
Abstract
Ohmic contacts are an important part of (Hg,Cd)Te infrared detectors. To achieve high sensitivity in staring detectors it is important that the noise be low at frequencies above the video frame rate. Low contact resistance is important both for high-frequency heterodyne detectors, where the resistance may determine the RC time constant of the detector, and for lower-frequency photodiodes because the 1/f noise of the diode junction strongly depends on the junction bias. If the contact resistance is too high, the operating bias on the detector shifts with changing photocurrent, so that even if the junction is optimally biased when looking at one scene, it is improperly biased when looking at a different scene, resulting in excess 1/f noise. Surface-sensitive measurements during overlayer growth on many semiconductors have shown that defects in the semiconductor induced by the metal strongly influence the electron transport between the two materials. These defects can be caused by such processes as chemical reactions, indiffusion of the contact metal, and outdiffusion of the semiconductor components and generally involve decomposition of the semiconductor near the interface. They are especially important during interactions between reactive metals and semiconductors with low thermodynamic stability, such as (Hg,Cd)Te.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA217088
Entities
People
- G. D. Davis
- W. Beck
Organizations
- Martin Marietta