Although CuFeS2 is known to be a semiconductor in the bulk with a bandgap of 0.5 eV, nanocrystals of the material exhibit many peculiar properties that were hitherto unforeseen in the bulk. Notably, CuFeS2 nanocrystals exhibit a localized plasmon resonance at ~500 nm, similar to the one observed in gold nanoparticles. As a result, CuFeS2 nanocrystals exhibit a strong resemblance to gold nanoparticles. Despite this, these nanocrystals still exhibit a photoresponse ranging all the way from visible to the NIR. These nanocrystals synthesized via colloidal techniques offer great ease of solution processing thus allowing them to be easily integrated into silicon-based electronics. For instance, forming a heterojunction between CuFeS2 nanocrystals and n-type silicon was found to result in a photodiode that can act as a photodetector with broadband response. Such a detector was found to have a photoresponse ranging from 460 nm to 2200 nm with microsecond response times. These heterojunction photodetectors further possess a slower bolometric response that allows them to sense thermal emitters. Here, I will briefly describe the fabrication, performance and underlying mechanism of CuFeS2 nanocrystal-bulk Silicon heterojunction photodetectors.

Broadband photodetection using CuFeS2 nanocrystals-n type silicon heterojunctions

ACS Spring Meeting 2021

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