Near Unity Absorption in Nanocrystal Based Short Wave Infrared Photodetectors using Guided Mode Resonators
Résumé
Nanocrystals appear as versatile building blocks for the design of low-cost optoelectronic devices. The design of infrared sensors based on nanocrystals is currently facing a key limitation: the short carrier diffusion length resulting from hopping transport makes that only a limited part of the incident light is absorbed. In order to enhance the device absorption, we use Guided Mode Resonance (GMR). The method appears to be quite versatile and is applied to both PbS and HgTe nanocrystals presenting respectively cut-off wavelengths at 1.7 and 2.6 µm. The designed electrodes present a large enhancement of the material responsivity around a factor of ≈250, reaching external quantum efficiency of 86% for PbS and 340% for HgTe. This increase of the response can be deconvoluted in a factor of 3 for the enhancement of the absorption and a factor of 80 for the photocurrent gain. The method can also be suited to finely tune the cut-off wavelength of the material thanks to geometrical parameters at the device level. The obtained devices are now only limited by the material noise.
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Chu et al. - 2019 - Near Unity Absorption in Nanocrystal Based Short W.pdf (853.2 Ko)
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