The effect of hydrogen on defects in AlGaN/GaN high-electron-mobility transistors (HEMTs) was investigated by using low-frequency noise (LFN) method. The results show that drain-to-source current of AlGaN/GaN HEMTs after hydrogen treatment is significantly larger than that of the fresh AlGaN/GaN HEMTs. The maximum variation of drain-to-source current is up to 80 mA at the gate-to-source voltage of 0 V and drain-to-source voltage of 5 V. The suppression of current collapse was also observed, and the gate-lag characteristic becomes better for the AlGaN/GaN HEMTs after hydrogen treatment. Extracted by the LFN method, the trap density decreases by about one order of magnitude in the AlGaN/GaN HEMTs after hydrogen treatment, and this would lead to less depleted electrons in the channel 2-D electron gas. The mechanism for the reduction of trap density could be attributed to H-passivated defects at AlGaN surface, AlGaN barrier layer, and heterostructure interface. The results of this paper may be useful in the design and application of AlGaN/GaN HEMTs.

A sub-wavelength plasmonic Au–Ge grating was used to enhance the responsivity of Ge-based metal–semiconductor–metal photodetectors at infrared communication wavelengths. Furthermore, a finite-difference time-domain simulation was performed to optimize absorption of light by the detectors. Characterizations of the photoelectronic properties of the optimized device revealed high-performance photodetection with a responsivity of 0.38 A/W and an external quantum efficiency of 30% for 1.55 μm wavelength incident light. Moreover, an enhancement peak across three infrared telecommunication bands (C-band, L-band, and U-band) was achieved in the plasmon-enhanced photodetector. According to the simulation results of the optical absorption spectra, the distributions of electric field, and absorbed power, the enhancements of responsivity and quantum efficiency could be ascribed to the surface plasmons at the Au/Ge interface. These plasmons boosted inter-band transition and internal photoemission effect simultaneously, enabling high efficient photodetection around the C-band. The results of the fabricated devices demonstrated the potential of this approach for achieving high-performance Ge-based photodetectors.

Wavelength selective imaging has a wide range of applications in image recognition and other application scenarios, which can effectively improve the recognition rate of objects. However, in the existing technical scenarios, it is usually necessary to use complex optical devices such as filters or gratings to achieve wavelength extraction. These methods inevitably bring about the problems of complex structure and low integration. Therefore, it is necessary to realize the wavelength extraction function at the device level. Here, we realize the wavelength extraction function and wide‐spectrum imaging function in the visible to infrared band based on a visible light absorber/floating gate storage layer/near‐infrared (NIR) photogating layer configuration. Under infrared irradiation, the device exhibits negative photoresponse through the absorption of infrared light by the Ge substrate and the photogating effect, and realizes visible positive light response through the absorption of visible light by MoS₂. Utilizing the memory function of the device, by cleverly changing the gate voltage pulse, the photoresponse state of the output voltage is effectively adjusted to achieve three imaging states: visible light response only, response to both visible and infrared light, and infrared light response only. Active selective imaging of the word “XDU” was achieved at 532 and 1550 nm wavelength. By using the photoresponse data of the device, the passive imaging of the topography of Xi'an, Shaanxi Province was obtained, which effectively improves the recognition rate of mountains and rivers. The proposed reconfigurable visible–infrared wavelength‐selective imaging photodetector can effectively extract image information and improve the image recognition rate while ensuring a simple structure. The single‐chip‐based spectral separation imaging solution lays a good foundation for the further development of visible–infrared vision applications. image