Jiwoon Lee

Quantum dots (QDs) have been explored for many photonic applications, both as emitters and absorbers. Thanks to the bandgap tunability and ease of processing, they are prominent candidates to disrupt the field of imaging. This review article illustrates the state of technology for infrared image sensors based on colloidal QD absorbers. Up to now, this wavelength range has been dominated by III–V and II–VI imagers realized using flip-chip bonding. Monolithic integration of QDs with the readout ch

In this letter, we present a small pixel pitch image sensor optimized for high external quantum efficiency in short-wavelength infrared (SWIR). Thin-film photodiodes based on PbS colloidal quantum dot (CQD) absorber allow us to exceed the spectral limitations of silicon’s absorption while maintaining the benefits of CMOS technology. By monolithically integrating PbS CDQ thin films with CMOS readout arrays, high-pixel density SWIR image sensors can be achieved. To overcome the remaining disadvant

Thin-film-based image sensors feature a thin-film photodiode (PD) monolithically integrated on CMOS readout circuitry. They are getting significant attention as an imaging platform for wavelengths beyond the reach of Si PDs, i.e., for photon energies lower than 1.12 eV. Among the promising candidates for converting low-energy photons to electric charge carriers, lead sulfide (PbS) colloidal quantum dot (CQD) photodetectors are particularly well suited. However, despite the dynamic research activ

A backside-illuminated (BSI) near-infrared (NIR)-enhanced silicon single-photon avalanche diode (SPAD) for time-of-flight (ToF) light detection and ranging applications is presented. The detector contains a 2- <inline-formula> <tex-math notation="LaTeX">$\boldsymbol {\mu }\text{m}$ </tex-math></inline-formula>-wide multiplication region with a spherically uniform electric field peak enforced by field-line crowding. A charge-focusing electric field extends into a 10- <inline-formula> <tex-math no

Damage to lower limb muscles requires accurate analysis of the muscular condition via objective microscopic diagnosis. However, microscopic tissue analysis may cause deformation of the tissue structure due to injury induced by external factors during tissue sectioning. To substantiate these muscle injuries, we used synchrotron X-ray imaging technology to project extremely small objects, provide three-dimensional microstructural analysis as extracted samples. In this study, we used mice as experi

Thin film photodiodes (TFPD) can supplement complementary metal-oxide-semiconductor (CMOS) image sensor vision by their exotic optoelectronic properties assisted by their monolithic processability. Halide perovskites are known to show outstanding optoelectronic properties, such as large absorption coefficient, long carrier diffusion lengths, and high carrier mobility, leading to high external quantum efficiency (EQE) and fast charge transport in photodiodes (PDs), especially compared with other

This brief presents offset and gain FPN calibrated linear-logarithmic image sensor. Offset FPN originated from threshold voltage variation of the logarithmic conversion transistor is calibrated with Two-step charge transfer operation. Remaining gain FPN is analyzed and its root cause is investigated. The subthreshold slope difference of the logarithmic conversion transistors in the shared pixel architecture is found to be responsible for the increasing FPN in the logarithmic operation region and

All-silicon highly-doped PN junction-based photodetectors, for photonic integrated circuit (PIC) calibration and power monitoring, are designed and fabricated in the C-band. The photodetector response is measured for different doping conditions. The photodetectors are integrated with an interferometric based phase-interrogator structure for a test calibration circuit. The measured devices show high responsivity (12 A/W) obtained under avalanche condition at 5.7 V reverse bias and reasonable dark

Abstract High‐performance, low‐cost, and energy‐efficient infrared (IR) photodetectors are central to next‐generation sensing technologies, but their advancement is constrained by the intrinsic limitations of conventional materials and band structure design. Here, a semimetal‐in‐oxide tellurium composite (Te‐in‐TeO x ) with an in situ‐formed gradient band structure is introduced, realized by a simple one‐step thermal evaporation process that utilizes the redox dynamics and distinct melting point

Electrical impedance tomography (EIT) has been studied to monitor lung ventilation because it is the only real-time lung imaging method without large equipment [1–2]. However, previous EIT systems just provided 2D cross-sectional image with limited spatial information of the lung and unneglectable volume detection error depending on the location of 2D EIT belt relative to the patient's lung. In spite of its importance, the 3D-EIT has not been realized in lung monitoring because it has many desig

In this article, the X-ray radiation effects on colloidal quantum dot photodiode (QDPD)-based short-wave infrared (SWIR) complementary metal-oxide semiconductor image sensors (QD-CISs) are studied. Individual QDPD, silicon readout IC (Si-ROIC), and QD-CIS are evaluated together for a comprehensive analysis. The dark current, activation energy, and external quantum efficiency (EQE) of samples are investigated before and after irradiating with 58.2 keV of X-ray radiation, which has a different tot

Quantum dot (QD) thin-film photodiodes (TFPDs) are studied extensively in the image sensor field as they can pave the way toward the cost-efficient implementation of short-wave infrared (SWIR) cameras. Interestingly, the QD TFPD image sensors can be operated in the global shutter (GS) mode by turning on the photodiode (PD) only during integration time and subsequently turning it off during the readout. This offers the substantial advantage of reducing the pixel size as it eliminates the need for

Functional magnetic resonance imaging (fMRI) leverages the blood-oxygen-level-dependent (BOLD) signals to gauge functional brain activation. Specifically, task-fMRI has become a predominant tool to investigate specific cerebral regions associated with diverse cognitive processes. A myriad of studies employing task-fMRI have harnessed both static functional connectivity (FC) and dynamic functional connectivity (dFC) to identify task-related biomarkers. However, while FC and dFC have proven their

Thin-film photodiodes (TFPD) monolithically integrated on the Si Read-Out Integrated Circuitry (ROIC) are promising imaging platforms when beyond-silicon optoelectronic properties are required. Although TFPD device performance has improved significantly, the pixel development has been limited in terms of noise characteristics compared to the Si-based image sensors. Here, a thin-film-based pinned photodiode (TF-PPD) structure is presented, showing reduced kTC noise and dark current, accompanied w