Optimization of sensor materials using physical vapor transport growth method
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A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chiping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.
A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chipping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.
Mass transport rate and composition of the transported material as a function of different process parameters like temperature, undercooling, inert gas pressure, and the source compactness for different PbTe(1-x)Se(x), compositions were studied. With a proper preparation procedures mass transport rates suitable for growth at the rate of 0.5 - 1 mm/h were obtained. Different composition non-uniformities in the deposited material were observed. Due to deviation of the PbTe-PbSe solid solution from ideality, congruent mass transport of the material takes place around X = 0.3. For other compositions an improved and even good uniformity can be achieved when a solid, premelted source material is used.