ROOM-TEMPERATURE MIDWAVELENGTH 2-COLOR INFRARED DETECTORS WITH HGCDTE/CDTE MULTILAYER STRUCTURES BY METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION

Two-color photoconductive detectors in the 3-5 mu m wavelength range using multilayer undoped n-type Hg1-xCdxTe heterostructures have been demonstrated at room temperature. These heterostructures, consisting of three or four Hg1-xCdxTe layers separated with CdTe layers, were grown by the metal-organic chemical-vapor-deposition (MOCVD) technique. The quality of MOCVD films was verified by near-theoretical values of the minority-carrier lifetime at 300 K, ranging from 0.8 to 4.7 mu s depending on the x value. The Hg1-xCdxTe layers are either detectors or filters, and the CdTe layers serve as insulating separators. The concept of using the exponential absorption tails of two Hg1-xCdxTe layers with different band gaps to form an absorption band was verified by the difference in the photoconductive spectral responses between backside and frontside illumination. Two different multilayer heterostructures with two-color peaks at 3.2/3.8 mu m and 3.7/4.6 mu m, respectively, were studied. (C) 1995 American Institute of Physics.