High-performance uncooled PbSe/CdSe nanostructured mid-infrared photodetector with tunable cutoff wavelength

Room-temperature (RT) high-performance mid-wavelength infrared (MWIR) Lead Selenide (PbSe)/Cadmium Selenide (CdSe) heterostructure nanocrystal photoconductors are designed and fabricated on commercial silicon dioxide on silicon (SiO2/Si) wafer via vapor phase deposition. Tunable absorption edges at 3.75 and 4.0 μm are demonstrated with different sizes of the nanostructure. The devices are annealed in oxygen to make the thin film much more sensitive to MWIR light. The detectors are etched by the reactive ion etching method to define an active area of 17.5 × 20 μm2. All devices exhibit external quantum efficiencies exceeding 100%, a clear indication of photoconductive gain. 1/f noise is the dominating noise source, and it follows Hooge's empirical relation for a homogeneous semiconductor. RT peak specific detectivity (D*) of 2.17 × 1010 and 1.61 × 1010 Jones is achieved for pixels with absorption edge at 3.75 and 4 μm, respectively.