Intraband Transition of HgTe Nanocrystals for Long-Wave Infrared Detection at 12 μm.
basic_science · Level V
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- Record sourced from PubMed, PMID 37027314.
- Also identified by DOI 10.1021/acsnano.2c12636.
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Abstract
The synthesis of n-doped HgTe colloidal quantum dots was optimized to produce samples with a 1S<sub>e</sub>-1P<sub>e</sub> intraband transition in the long-wave infrared (8-12 μm). The spin-orbit splitting of 1P<sub>e</sub> states places the 1S<sub>e</sub>-1P<sub>e1/2</sub> transition around 10 μm. The narrow line width of 130 cm<sup>-1</sup> at 300 K is limited by the size distribution. This narrowing leads to an absorption coefficient about 5 times stronger than is possible with the HgTe CQD interband transition at similar energies. From 300 to 80 K, the intraband transition blueshifts by 90 cm<sup>-1</sup>, while the interband transition redshifts by 350 cm<sup>-1</sup>. These shifts are assigned to the temperature dependence of the band structure. With ∼2 electrons/dot doping at 80 K, a photoconductive film of 80 nm thickness on a quarter wave reflector substrate showed a detectivity (<i>D</i>*) of ∼10<sup>7</sup> Jones at 500 Hz in the 8-12 μm range.