Indium antimonide deposition

This type of detector is constituted, for the mid-IR region, of a ternary alloy of mercury-cadmium telluride (MCT) or indium antimonide (InSb) deposited upon an inert support and for the near-IR of lead sulfide (PbS) or an other ternary alloy of indium/gallium/arsenic (InGaAs). Sensitivity is improved when these detectors are cooled down to liquid nitrogen temperature of (77 K). 

Photon detectors consist of a thin film of semiconductor material, such as lead sulfide, lead telluride, indium antimonide, or germanium doped with copper or mercury, deposited on a nonconducting glass and sealed into an evacuated envelope. Photon flux impinging on the semiconductor increases its conductivity. Lead-sulfide detectors are sensitive to radiation below about 3 fj.m in wavelength and have a response time of about 10 /nsec. Doped germanium detectors cooled to liquid-helium temperatures are sensitive to radiation up to about 120 jitm in wavelength, and have a response time of approximately 1 nsec. 

Tlie detector consists of a 256 X 256 array of indium antimonide mesa photodiodes. These detectors are made by diffusing a sheet junction into a wafer of indium antimonide material. Afterwards, the diodes are delineated with a deep mesa trench, and then passivated. The wafer is attadied to a substrate and thinned to the correct thickness. The individual diodes receive a contact metallization, followed by an indium bump deposition. The die are then sawn from the wafer, screened, and are then ready to be naated to multiplexers. 

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