Room temperature infrared detectors made of PbTe/CdTe multilayer composite

We report on fabrication and characterization of infrared detectors made of a composite material-PbTe/CdTe multilayer (ML). The multilayer consists of 10 repetitions of 35nm thick PbTe layers and 75nm thick CdTe layers grown by molecular beam epitaxy on GaAs (100) semi-insulating substrates. Simple technological methods were used to manufacture photoresistors from the structure containing the PbTe/CdTe composite. The front-side illuminated photodetectors show a cut-off wavelength of 3.57 mu m and a peak current responsivity of 127mA/W at a bias voltage of 10V, a frequency of 730Hz, and a temperature of 300K. The specific detectivity of photoresistors at the peak wavelength of 2.9 mu m equals 2.7x10(10)cm.Hz(1/2)/W and 6.1x10(9)cm.Hz(1/2)/W for 77 and 300K, respectively. Although the ML photoresistors were not optimized, neither antireflection coated nor lithographically defined, their detectivity, especially at room temperature, is highly comparable to that of photoconducting infrared detectors available in the market. Possible mechanisms causing the relatively high performance of PbTe/CdTe ML detectors have been discussed in detail. These are a decrease in the electron concentration in the conducting PbTe layers caused by capturing some mobile electrons by dangling bonds present at the PbTe/CdTe interfaces and the effective suppression of the Auger recombination in nanostructures made of narrow and wide bandgap semiconductors.