Wafer-Scale Fabrication of CMOS-Compatible Trapping-Mode Infrared Imagers with Colloidal Quantum Dots

Abstract

Silicon-based complementary metal oxide semiconductor (CMOS) devices have dominated the technological revolution in the past decades. With increasing demands in machine vision, autonomous driving, and artificial intelligence, silicon CMOS imagers, as the major optical information input devices, face great challenges in spectral sensing ranges. In this paper, we demonstrate the development of CMOS-compatible infrared colloidal quantum-dot (CQD) imagers in the broadband short-wave and mid-wave infrared ranges (SWIR and MWIR, 1.5–5 μm). A new device architecture of trapping-mode detectors is proposed, fabricated, and demonstrated with lowered darkcurrents and improved responsivity. The CMOS-compatible fabrication process is completed with two-step sequential spin-coating processes of intrinsic and doped HgTe CQDs on an 8 in. CMOS readout wafer with photoresponse non-uniformity (PRNU) down to 4%, dead pixel rate of 0%, external quantum efficiency up to 175%, and detectivity as high as 2 × 1011 Jones for extended SWIR at 300 K and 8 × 1010 Jones for MWIR at 80 K. Both SWIR images and MWIR thermal images are demonstrated with great potential for semiconductor inspection, chemical identification, and temperature monitoring.

In Situ Mapping of the Vectorial Electric Field within a Nanocrystal-Based Focal Plane Array Using Photoemission Microscopy

“…A responsivity value above ≈2 A•W −1 corresponds to the EQE above 100%, which is the signature of photogain in this system. 13,28,29 FET measurements (Figure 1c) have shown a ptype behavior for the material, which may seem surprising given the fact that the hole effective mass in HgTe is 25 times heavier than the electron effective mass, 30 prompting further clarification. Under illumination, photo-holes provide charge transport, while electrons with their reduced mobility behave almost as trapped.…”

“…However, high performance and compatibility with technological developments required by focal plane array (FPA) integration are crucial for the widespread adoption of this technology. Several groups and companies − have been exploring the use of NCs as an active layer for infrared FPAs relying either on PbS , or HgTe − NCs, the latter being the only one to cover both the short- and mid-wave infrared …”

Mercury telluride colloidal quantum-dot focal plane array with planar p-n junctions enabled by in situ electric field–activated doping

“…The PbS CQD-based focal plane arrays (FPAs) with spectral response range from 400 to 1300 nm have been reported (4). Mercury telluride (HgTe) CQDs with gap-less characteristics in bulk form have the potential for extending spectral response ranges to SWIR, MWIR, and LWIR and being monolithically integrated with Si ROICs to realize high-resolution infrared imaging (16,17,(29)(30)(31).…”

Bias Reconfigurable Photoresponse of an Infrared Nanocrystal Film Integrated into a Coupled Fabry-Perot Resonator

“…In the infrared, the prospect of bringing cost disruption to a spectral region where detectors and sources are dramatically more expensive than their counterparts operating in the visible range has also spurred interest in colloidal nanomaterials. Some clear successes have been obtained through the design and fabrication of components such as on-chip integrated sensors, , infrared cameras, − spectrometers, and LEDs. , …”