Characterization and Optimization of Hg sub 1-x Cd sub x Te Infrared Detector Materials.
Final rept. 1 Jun 72-31 Dec 74,
SOUTHERN METHODIST UNIV DALLAS TEX INST OF TECH
Pagination or Media Count:
The objective of this contract was to characterize the ternary compound Hg1-xCdxTe. Emphasis was primarily placed on the 0.1 eV composition because of its utility as an intrinsic infrared photoconductor. A distinct advantage of these materials as a photoconductor operating at the longer wavelengths is their high absorption coefficient which allows operation at higher temperatures and also thinner samples. It has been well established that HgCdTe can be fabricated with the necessary composition to yield suitable detectors with the desired wavelength response and meeting the basic criteria for intrinsic photoconductors. However, as in the development of any solid state system, the metallurgical surfaces can degrade performance. In the case of HgCdTe detectors, the various surface treatments used during fabrication can greatly influence detector performance by changing the electrical and photoconductive properties. For example, treatment wity H2O2 is known to accumulate the surface whereas, methonalbromine depletes the surface of electrons. Since the noise voltage is greater for a depleted surface than for an accumulated surface, it appears than an accumulated surface is more desirable for photoconductors. In order to better understand the surface and its influence on the bulk properties, the technical effort in this program was divided into three parts 1 measurement of bulk transport properties utilizing galvano-thermomagnetic measurements 2 determination of surface state distributions from capacitance-voltage C-V and capacitive derivative-voltage C-V measurements on metal-insulator-semiconductor MIS structures, and 3 low frequency lf noise measurement.
- Infrared Detection and Detectors
- Solid State Physics