Thallium-Doped Silicon Infrared Detector Material.
Abstract
Thallium-doped silicon crystals were grown by temperature gradient transport from a solution consisting of silicon dissolved in a tin-thallium liquid-metal solvent. Thallium concentrations in excess of 10 to the 17th power/cc were obtained. The highest thallium doping concentration, 1.33 x 10 to the 17th power T1/cc, was obtained in material grown using a solvent of 86% T1 and 14% Sn at a growth temperature of 1370 degrees C. Various amounts of shallow acceptor impurities were observed in all of the material grown during the program. From Hall measurements, boron concentrations as high as 1.9 x 10 to the 16th power/cc were observed. A method for encapsulating thin layers (0.1mm thick) of 50% Sn and 50% Tl metal solvent within a silicon source-substrate assembly was developed. This approach was found to eliminate the boron contamination and produce uniform crystal growth. The samples grown exhibited quantum efficiency values as high as 18% at 3.1 microns. The thallium optical cross section at 3.1 microns was 1.45 x 10 to the 17th power/sq cm. Dislocation density measurements were made on some samples which fell in the 5,000 to 8,000 sq cm range.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1981
- Accession Number
- ADA120720
Entities
People
- D. E. Schafer
Organizations
- Honeywell International, Inc.