Mid-infrared (MIR) photodetection has been dominated by state-of-the-art molecular beam-processed materials such as HgCdTe and InAs. However, the cost of materials and processing restricts the utility of these detector technologies to research and defense applications. In the MIR, HgTe colloidal quantum dots (CQD) are a cheap, solution-processed, and MIR tunable semiconductor nanomaterial, which has demonstrated the potential for next generation infrared photodetection.
We will show that HgTe CQD MIR photodetectors have improved more than 10-fold with respect to previous reports. We will discuss the influence of interfacial layers for device performance with characterization by current-voltage-temperature measurements, FTIR, photoluminescence, EDX, and XPS. When operating under zero bias, we achieve a specific detectivity (D*) of 1x1011 Jones at 90K with Background Limited Infrared Photodetection (BLIP) and cutoff wavelength between 3-5 μm. HgTe CQD MIR photodetectors achieve D* above 109 Jones at 230K and 4.2μm cutoff, approaching the performance of epitaxial HgTe.