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Recently, there have been numerous studies on utilizing surface treatments or photosensitizing layers to improve photodetectors based on 2D materials. Meanwhile, avalanche breakdown phenomenon has provided an ultimate high‐gain route toward photodetection in the form of single‐photon detectors. Here, the authors report ultrasensitive avalanche phototransistors based on monolayer MoS2 synthesized by chemical vapor deposition. A lower critical field for the electrical breakdown under illumination shows strong evidence for avalanche breakdown initiated by photogenerated carriers in MoS2 channel. By utilizing the photo‐initiated carrier multiplication, their avalanche photodetectors exhibit the maximum responsivity of ≈3.4 × 107 A W−1 and the detectivity of ≈4.3 × 1016 Jones under a low dark current, which are a few orders of magnitudes higher than the highest values reported previously, despite the absence of any additional chemical treatments or photosensitizing layers. The realization of both the ultrahigh photoresponsivity and detectivity is attributed to the interplay between the carrier multiplication by avalanche breakdown and carrier injection across a Schottky barrier between the channel and metal electrodes. This work presents a simple and powerful method to enhance the performance of photodetectors based on carrier multiplication phenomena in 2D materials and provides the underlying physics of atomically thin avalanche photodetectors. [ABSTRACT FROM AUTHOR]

Decomposition of the positive gate-bias temperature stress (PBTS)-induced instability into contributions of distinct mechanisms is experimentally demonstrated in top-gate self-aligned coplanar amorphous InGaZnO thin-film transistors and validated by reproducing the PBTS time-evolution of I-V characteristics through the TCAD simulation into which the extracted density-of-states and charge trapping are incorporated. [ABSTRACT FROM AUTHOR]

Decomposition of the positive gate-bias temperature stress (PBTS)-induced instability into contributions of distinct mechanisms is experimentally demonstrated at several temperatures in top-gate self-aligned coplanar amorphous InGaZnO thin-film transistors by combining the stress-time-divided measurements and the subgap density-of-states (DOS) extraction. It is found that the PBTS-induced threshold voltage shift (ΔVT) consists of three mechanisms: (1) increase of DOS due to excess oxygen in the active region; (2) shallow; and (3) deep charge trapping in the gate insulator components. Corresponding activation energy is 0.75, 0.4, and 0.9 eV, respectively. The increase of DOS is physically identified as the electron-capture by peroxide. Proposed decomposition is validated by reproducing the PBTS time-evolution of I-V characteristics through the technology computer-aided design simulation into which the extracted DOS and charge trapping are incorporated. It is also found that the quantitative decomposition of PBTS-induce ΔVT accompanied with the multiple stretched-exponential models enables an effective assessment of the complex degradation nature of multiple PBTS physical processes occurring simultaneously. Our results can be easily applied universally to any device with any stress conditions, along with guidelines for process optimization efforts toward ultimate PBTS stability. [ABSTRACT FROM AUTHOR]