Organic Photodiode Integration on Si Substrates beyond 1000 nm Wavelength

Abstract

Organic photodiode integration on the Si readout circuit offers a solution for extending the sensitivity beyond 1000 nm. In this work, we report the way to integrate organic photodiodes on Si substrates with metals that are complementary metal–oxide–semiconductor process-compatible as bottom electrodes, such as titanium nitride (TiN), tungsten (W), and aluminum (Al). We report on a high-efficiency near-infrared sensor enabled by employing TiN and W as bottom electrodes, with an external quantum efficiency of ∼50% at 940 nm and ∼70% at 1030 nm, a dark leakage current density of 15 nA/cm2, a bandwidth of 15 kHz at −4 V, and a dynamic range of ∼100 dB. Low resistivity and inert properties of TiN make it form a good interface with the organic active layer, leading to an ideal bottom-contact metal for the organic photodiode when integrated on the Si substrate.

Bias switchable narrowband/broadband NIR organic photodetector fabricated with a scalable technique

“…5a). 22 This measurements where performed at 520 nm by illuminating the photodetector with a fast response LED and putting a circuit in series with the OPD with a 50-ohm shunt resistance whose voltage drop is measured by a lock-in amplifier. After scanning from 10 Hz to 100 000 kHz, the voltage values read from the lock-in amplifier are normalized to their maximum.…”

“…Recently, we have shown the possibility of integrating OPDs on Si wafers for the application of visible-to-infrared broadband image sensor, where the photodetector showed external quantum efficiency (EQE) of ∼50% at 940 nm, and ∼61% at 1030 nm, with a dark leakage current density of 15 nA cm −2 , a bandwidth of 15 kHz at −4 V, and a dynamic range (DR) of ∼100 dB. 21,22 However, additional interference-type multi-layer filters are required on the photodetectors to realize narrowband imaging. These multi-layer filters suffer from strong spectral distortion when the incident angle is larger than 30°, limiting large field of view (FOV) application, such as augmented reality (AR) and virtual reality (VR).…”

Suppressing the Dark Current While Improving the Quantum Efficiency in Shortwave Infrared Organic Photodetectors Through Naphthalenediimide‐Based Interlayer

“…This breakthrough technology not only promises to bridge the gap in SWIR sensor availability but also opens doors to innovative applications across various industries, ranging from automotive and surveillance to medical imaging and beyond. [ 9 ] In recent years, remarkable advancements have been made in utilizing organic semiconductors as the photoelectric conversion layer in SWIR photodetectors. In addition to the inherent optoelectronic characteristics of organic semiconductors within the SWIR spectrum, organic photodetectors (OPDs) have garnered significant research attention for photodetection and imaging technologies due to their noteworthy advantages, including high responsivity, a broad dynamic range, and the ease of large‐area fabrication through solution coating.…”

Highly Sensitive Resonance-Enhanced Organic Photodetectors for Shortwave Infrared Sensing

“…Solution-processable organic photodetectors (OPDs) are arising as a cost-effective near-infrared (NIR) and infrared (IR) sensing platform, along with other attractive properties such as light weight, flexible, compatibility with mass-production processes (roll-to-roll, blade coating), etc. − Recent developments of nonfullerene acceptors (NFAs) and extensive efforts on device engineering have enabled high-detectivity NIR OPDs (∼10 13 Jones at λ = 940 nm), − with impressive external quantum efficiency (EQE > 50% at λ = 940 nm), − low dark current density at a reverse bias (sub-nA/cm 2 ), ,− and mega-hertz cutoff bandwidth. − Remarkably, some NFA-based OPDs have demonstrated sizable photoresponse in the SWIR range of 1000 nm ≤ λ < 1100 nm. ,,,,− For instance, by adopting an ultrathick active layer (∼8.2 μm) of PD004:PD-A2 bulk heterojunction (BHJ), Tsai et al realized a self-filtered OPD with EQE = 53%, at −8 V and λ = 1080 nm . Yet, to the best of our knowledge, there are no high-performance NFA-based OPDs with EQE > 20% for λ ≥ 1100 nm.…”