Guided-Mode Resonator Coupled with Nanocrystal Intraband Absorption

Abstract

Intraband absorption in doped nanocrystals offers an interesting alternative to narrow band gap materials to explore mid infrared optoelectronic device designs. However, the performance of such device clearly lags behind the ones relying on intrinsic materials. Livache et al. have proposed a dye sensitized approach to overcome the limitations observed from intraband materials (high dark current, slow response, low activation energy), where the intraband absorber is coupled to an undoped material which takes care of the charge conduction. Here, we unveil the coupling between both materials using mid-infrared transient reflectivity (TR) measurement. We show that hybrid material displays a unique feature in the TR signal that we attribute to a charge transfer and for which the dynamic matches the hopping time. We then developed a strategy to enhance the photodetection performances of the hybrid material by coupling for the first time intraband absorption to a light resonator. The latter is used to enhance the absorption by a factor 4 and enables an increase of the operating temperature by 80 K compared to the reference device. The obtained device matches the performance of best devices relying on intraband absorption.

Mid-Infrared Intraband Photodetector via High Carrier Mobility HgSe Colloidal Quantum Dots

“…Efforts have been made on improving the response speed on HgSe CQDs by surface chemical modification, 49 mobility improvement, and modified device design with resonator coupling. 26,50 As discussed above, this high-mobility CQD surface would be well modified with no obvious trapping but controllable doping. The fast response speed is comparable to interband HgTe CQD photoconductors in the mid-IR range (Supporting Information).…”

“…This is also observed by previous research that pure intraband detectors shows the response speed tens of msec, due to uncontrollable doping density, midgap or trap states, − and low-mobility carriers not following similar paths. Efforts have been made on improving the response speed on HgSe CQDs by surface chemical modification, mobility improvement, and modified device design with resonator coupling. , As discussed above, this high-mobility CQD surface would be well modified with no obvious trapping but controllable doping. The fast response speed is comparable to interband HgTe CQD photoconductors in the mid-IR range (Supporting Information).…”

The Historical Development of Infrared Photodetection Based on Intraband Transitions

“…The CdS shells increased the intraband emission intensity. In 2022, Adrien Khalili et al unveiled the coupling between HgSe and HgTe materials by using the mid-infrared transient reflectivity measurement ( Figure 6 c) [ 62 ]. This structure of HgSe and HgTe preserved the intraband absorption of HgSe, reduced the dark current, and boosted the time response.…”

High-operating-temperature mid-infrared photodetectors via quantum dot gradient homojunction

“…Colloidal quantum dot (CQD), taking the advantages of cheap chemical synthesis and solution processability 8 , 9 , could provide an ideal platform for QD photodetector investigations 10 . In the last 10 years, CQDs have been successfully applied for mid-IR photodetection 11 , such as photoconductor 12 , 13 , phototransistor 14 , heterojunction 15 , 16 photovoltaic devices 17 – 19 , optical structures enhanced devices 20 , and dual band photovoltaic devices with multijunction 18 , 21 . The background-limited performance (BLIP) has been achieved for mid-IR CQD photodetectors at cryogenic temperature 18 , 20 .…”