HgCdTe mid-Infrared photo response enhanced by monolithically integrated meta-lenses

Abstract

for S m = 5 μm × 5 μm or S m = 10 μm × 10 μm. Further, the meta-lens exhibits a good dispersion tolerance over the wavelength range from 3.3 μm to 5 μm. The averaged detectivity enhancement over this spectrum range is around 3 times for S m = 5 μm × 5 μm and 2 times for S m = 10 μm × 10 μm. The angular response of the meta-lens integrated detector depends on the focal length. For a focal length of 73 μm, the AOV for a 5 μm × 5 μm photosensitive area is 4.0°. When the focal length is reduced to 38 μm, the AOV for a 5 μm × 5 μm photosensitive area increases to 7.7° and it reaches 15.4° for a 10 μm × 10 μm photosensitive area. For the inter-pillar distance to be 2 μm in our design, the influence of the coupling effect between the nano-pillars on the performance of the meta-lens is little. Therefore, the monolithic integration of a meta-lens provides us a promising way to enhance the performance of infrared photodetectors and even focal plane arrays.

Simulation of Monolithically Integrated Meta-Lens with Colloidal Quantum Dot Infrared Detectors for Enhanced Absorption

“…For a meta-lens with diameter of 200 µm, the diameter of the focused region is around 10-20 µm, depending on the NA (Figure 3b). Overall, the enhancement ratio of light intensity in the focused region is ~20, which is similar to previously reported experimental values [26].…”

“…Therefore, the employment of meta-lenses as optical concentrators could improve the detectivity by a factor of 32. Previous experimental studies of HgCdTe with meta-lenses reported an enhancement ratio of ~5.5, demonstrating that the concept of integration of meta-lenses with infrared detectors should work [26]. The current study mainly focuses on simulation and theoretical calculation, and experimental tests would be conducted to verify such an enhancement factor in the future.…”

Engineering sensitivity and spectral range of photodetection in van der Waals materials and hybrids

“…Graphene/HgCdTe heterostructure infrared photodetectors shows responsivity of 2.60 A W −1 working upto mid-infrared wavelength region of 5.2 μm [151]. The state-of-the-art research in HgCdTe alloys has shown enhancement in MIR photoresponse as well as detectivity by integrating monolithically with meta lenses [152]. Ge/perovskite heterostructure photodetector, operating at 1550 nm shows responsivity of 1.4 A W −1 at a low bias of 1 V. The perovskite coating gives the lowest reflection at 1550 nm wavelength and along with type 1 band alignment, aids charge transport from perovskite to Ge [153].…”

Recent Progress in Improving the Performance of Infrared Photodetectors via Optical Field Manipulations

“…Ndao et al [128] achieved polarization-insensitive, ultrawideband achromatic focusing at visible-near infrared wavelengths by numerical optimization algorithms, and the focusing efficiency exceeded 70%. Li et al [155] reported on monolithically integrating a dielectric polarization-independent metalens into a HgCdTe infrared photodetector, as shown in Figure 7q. The metalens can enormously improve the absorptance, meanwhile reducing the photosensitive area and enhancing the detectivity.…”