The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202105485.Human behavior (e.g., the response to any incoming information) has very complex forms and is based on the response to consecutive external stimuli entering varied sensory receptors. Sensory adaptation is an elementary form of the sensory nervous system known to filter out irrelevant information for efficient information transfer from consecutive stimuli. As bioinspired neuromorphic electronic system is developed, the functionality of organs shall be emulated at a higher level than the cell. Because it is important for electronic devices to possess sensory adaptation in spiking neural networks, the authors demonstrate a dynamic, real-time, photoadaptation process to optical irradiation when repeated light stimuli are presented to the artificial photoreceptor. The filtered electrical signal generated by the light and the adapting signal produces a specific range of postsynaptic states through the neurotransistor, demonstrating changes in the response according to the environment, as normally perceived by the human brain. This successfully demonstrates plausible biological sensory adaptation. Further, the ability of this circuit design to accommodate changes in the intensity of bright or dark light by adjusting the sensitivity of the artificial photoreceptor is demonstrated. Thus, the proposed artificial photoreceptor circuits have the potential to advance neuromorphic device technology by providing sensory adaptation capabilities.

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We optimized Ni/Ag-based p-type reflectors for the improvement of efficiency of 273 nm deep ultraviolet (DUV) AlGaN-based flip-chip light emitting diodes (FCLEDs). The Ni(3 nm)/Ag(5–15 nm)/Al/Ni and Ni(25–50 nm)/Ag/Ni contacts exhibited higher reflectance (36.4–39.5%) at 273 nm than reference Ni(5 nm)/Au(5 nm)/Al/Ni contact (26.1%). The Ni(3 nm)/Ag/Al(200 nm)/Ni(20 nm) and Ni/Ag(200 nm)/Ni(20 nm)-based FCLEDs gave forward voltages in the rage of 6.93–7.11 V and 5.5–6.28 V at 20 mA, respectively, whereas the Ni/Au-based sample showed 6.35 V. Further, the Ni(3 nm)/Ag(10 nm)/Al/Ni-based and Ni(50 nm)/Ag(200 nm)/Ni-based samples exhibited 4.85% and 13.4% larger output power at 1.2 W than the reference sample. The Ni(3 nm)/Ag(10 nm)-based and Ni(50 nm)/Ag(200 nm)/Ni-based samples produced 5.6% and 8.5% higher peak external quantum efficiency than the reference sample. It was further shown that the Ni(3 nm)/Ag(10 nm)/Al/Ni-based and Ni(50 nm)/Ag(200 nm)/Ni-based samples experienced less efficiency droop (namely, 27.9 and 26.4%, respectively) than the reference sample (31.4%). Based on the scanning transmission electron microscopy and X-ray photoemission spectroscopy results, the ohmic formation mechanism is described and discussed.

We investigated the output performance of UV LEDs with Ag-Pd-Cu (APC) and Ag-only reflectors. After annealing at 600°C, the Ag-only layer surface was seriously roughened, while the APC sample revealed a smooth surface with hillocks. The 600 °C-annealed APC and Ag samples gave reflectance of 84.9% and 70.9%at 385 nm. The contact resistivities of the Ag and APC contacts annealed at 500 °C were measured to be 2.59×10– 4 and 1.85×10– 4 Ωcm2, respectively. For the annealed APC sample, the Ga 2p core level was shifted towards the lower binding-energies by 0.67 eV as compared to that of the as-deposited sample. The UV LEDs with the annealed APC reflector yielded 9.04% higher output at 100 mA than those with the Ag reflector. Based on the XRD pole figure and SEM results, the better thermal property of the APC sample is described in terms of thermal stress and surface energy.

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