ON Semiconductor (Taiwan)

Abstract Silicon photonics is increasingly important for advancing optical communication networks. The reliability testing of silicon photonics is a critical issue. This study demonstrates damp heat and temperature cycling reliability tests for silicon photonics, followed by failure analysis (FA).

This paper presents two PZT piezoelectric micromachined ultrasonic transducer (PMUT) designs for distance sensing applications, fabricated using a foundry-compatible multi-project wafer (MPW) process. By leveraging distinct PZT mode shapes within identical suspended membrane areas, the PMUTs achieve enhanced operating frequencies and sensitivity. The single-mode and differential-mode PMUTs operate at resonant frequencies of 849 kHz and 2.39 MHz, which correspond to maximum sensing distances of 2.5 cm and 2 cm, respectively. The measured sensitivities are 226.7 nm/V and 9.6 nm/V for actuation and 0.18 mV/nm and 1.07 mV/nm for sensing. At ~0.5 cm, the differential-mode PMUT offers 1.78 times the sensitivity of the single-mode. Furthermore, at ~ 1.5 cm, ultrasonic signal attenuation caused by biological obstacle (e.g., a finger) remains minimal at approximately 5%.

Halide perovskites are promising in the development of multijunction solar cells with enhanced power conversion efficiency (PCE) compared to that of single-junction solar cells. Besides the optimal design limitation for mitigating optical and electrical losses, amalgamating different perovskite absorber layers with optimized bandgap and thickness for a multijunction cell is a topic of concern. Herein, we demonstrate a facile and cost-effective technique called a double-sided sandwich evaporation technique for fabricating a pure and mixed-halide-based perovskite absorbing layer. By tuning the halide ratio and B-site doping, we successfully fabricated MAPbIxBr3–x, MAPbIxCl3–x, and MAPbxSn1–xI3, formulating a triple-junction tandem solar cell. The solar cell configuration MAPbIxBr3–x (1.96 eV)/MAPbIxCl3–x (1.593 eV)/Si (1.12 eV) exhibited a higher PCE of 25.84% as compared with the original bandgap combination of MAPbIxBr3–x (1.96 eV)/MAPbxSn1–xI3 (1.31 eV)/Si (1.12 eV), showing a PCE of 24.62%. Moreover, theoretical insight for the optimal perovskite thickness was gained using SETFOS by taking into account the reflection of the bottom cell, so the thickness of the top layers could be reduced. The result shows that in the thinner upper and middle perovskite cells, the light absorption ratio of each subcell can be effectively distributed, resulting in a triple-junction tandem solar cell with a PCE of 26.40%.

Graphene-on-silicon photodetectors exhibit broadband detection capabilities with high responsivities, surpassing those of their counterpart semiconductors fabricated purely using graphene or Si. In these studies, graphene channels were considered electrically neutral, and signal amplification was typically attributed to the photogating effect. By contrast, herein, we show graphene channels to exhibit p-type characteristics using a structure wherein a thin oxide layer insulated the graphene from Si. The p-type carrier concentration is higher (six-times) than the photoaging-induced carrier concentration and dominates the photocurrent. Additionally, we demonstrate photocurrent tunability in the channel. By operating this device under a back-gated bias, photocurrent tuning is realized with not only amplification but also attenuation. Gate amplification produces a current equal to the photogating current at a low bias (0.2 V), and it is approximately two orders of magnitude larger at a bias of 2 V, indicating the operation effectiveness. Meanwhile, photocurrent attenuation enables adjustments in the detector output for compatibility with read-out circuits. A quantification model of gate-dependent currents is further established based on the simulation model used for metal–oxide–semiconductor devices. Thus, this study addresses fundamental issues concerning graphene channels and highlights the potential of such devices as gate-tunable photodetectors in high-performance optoelectronics.

Population expansion of the black‐winged kite Elanus caeruleus has been a global trend in recent decades. Since first recorded in Taiwan in 2001, they rapidly occupied plains areas of this subtropical island which has led to interspecific competition with the wintering Eurasian kestrel Falco tinnunculus . In this study, we analyzed historical surveys to estimate the population trends of both species in Taiwan. We then used Pianka's index to quantify the degree of niche overlap based on diet composition and foraging peaks. Finally, we designed an experiment to test the aggressiveness of the two raptors when facing conspecific or heterospecific intruders. Airport avifauna survey (2002–2017) data from eight different airports and eBird data (2000–2019) from 21 hotspot grids both showed population turnover between the two raptors, with a decline in the wintering Eurasian kestrel and an expansion of the black‐winged kite. Rodents were the largest share of prey for both species, indicating that the two raptors have a high degree of niche overlap (an overlap index of 0.74 by prey frequency, 0.97 by prey biomass and 0.89 by foraging time). The black‐winged kite exhibited higher boldness and aggressiveness toward intruders, with its aggressiveness toward kestrel specimens (2.9 ± 2.4 strikes) significantly higher than that toward kite specimens (1.1 ± 1.8 strikes). Attacks by the black‐winged kite may have prompted the Eurasian kestrel to choose other wintering grounds. As a result, the number of wintering kestrels decreased, leading to opposing population trends of the two species.