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Deep-ultraviolet (DUV) phototransistors have shown great potential applications in UV imaging, artificial intelligence, and wearable optoelectronics. Among a large number of wide bandgap semiconductors, the quasi-two-dimensional β-Ga2O3 is considered as an ideal candidate for DUV photodetector applications. Herein, we report a high responsivity (R) and fully flexible Ta-doped β-Ga2O3 DUV phototransistor which exhibits outstanding optoelectrical properties with a high R of 1.32 × 106 A/W, a large detectivity of 5.68 × 1014 Jones, a great photo-to-dark current ratio of 1.10 × 1010%, a high external quantum efficiency of 6.60 × 108%, and an ultra-fast response time of ~3.50 ms. Besides, the flexible Ta-doped β-Ga2O3 device also displays high reliability and mechanical flexibility that can sustain well after over 1 × 104 bending cycles. Moreover, high-contrast imaging of UV light was obtained on the flexible DUV detector arrays, which can be efficiently trained and recognized by an artificial neural network. Our findings offer a perspective to develop wearable optoelectronics and UV imaging based on high-performance flexible β-Ga2O3 DUV phototransistors, providing an inspiration for the future work in artificial intelligence and bionic robot fields. [ABSTRACT FROM AUTHOR]

We present a computational study of the plasmon resonances in a periodic square coaxial hole array in a graphene sheet, which consists of a square hole array and a square strip array. According to charge oscillation picture, we find that a new plasmon mode, which locates on the edges of square hole along the polarization direction of incident light, emerges in our proposed structure. Two hybridized plasmon resonance modes (i.e., symmetric and asymmetric plasmon resonance modes) are formed due to two different manners of coupling between the new plasmon mode of square hole and the plasmon mode of square strip. The two plasmon resonance modes can be tuned over a wide wavelength range by a small change in the chemical potential of graphene. Furthermore, the two plasmon resonances can also be controlled by changing L and L (which are the strip offsets from the hole center perpendicular and parallel to the polarization direction of incident light, respectively), originating from the change in the strength of electromagnetic coupling between square hole and square strip. Our study gives an insight into the physical mechanism of plasmon resonances in square graphene coaxial hole array, and our findings will be useful for designing graphene-based plasmonic devices and metamaterials. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the plasmon resonances in a stacked pair of periodic graphene hole arrays by using charge oscillation picture. It is found that the plasmon resonances can be controlled by changing the longitudinal interval G between two arrays, and the lateral displacements L and L, which are parallel and perpendicular to the polarization direction of the incident light, respectively. The plasmon resonance can be tuned over a wide wavelength range by a small change of G due to its influence on the strength of electromagnetic coupling between two arrays. The lateral displacement L causes new plasmon resonance modes, originating from the appearance of new electromagnetic coupling manners, while the lateral displacement L leads to the splitting of plasmon resonance mode, which results from two different electromagnetic coupling manners. Our study gives an insight into the physical mechanism of plasmon resonances in two graphene hole arrays, and our findings may hold great promise in designing graphene-based plasmonic devices and metamaterials. [ABSTRACT FROM AUTHOR]

The optoelectronic performance of the mid-wavelength HgCdTe infrared focal plane array (IRFPA) with refractive microlenses integrated on its CdZnTe substrate has been numerically simulated. A reduced light-distribution model based on scalar Kirchhoff diffraction theory was adopted to reveal the true behavior of IRFPAs operating in an optical system under imaging conditions. The pixel crosstalk obtained and the energy-gathering characteristics demonstrated that the microlenses can delay the rise in crosstalk when the image point shifts toward pixel boundaries, and can restrict the major optical absorption process in any case within a narrow region around the pixel center. The dependence of the microlenses' effects on the system's properties was also analyzed; this showed that intermediate relative aperture and small microlens radius are required for optimized device performance. Simulation results also indicated that for detectors farther from the center of the field of view, the efficacy of microlenses in crosstalk suppression and energy gathering is still maintained, except for a negligible difference in the lateral magnification from an ordinary array without microlenses. [ABSTRACT FROM AUTHOR]

The current study investigates GaN-based light-emitting diodes (LEDs) with InGaN/GaN/InGaN multi-layer barrier (MLB). Simulation results show that GaN-based LEDs with MLB have better performance than conventional GaN-based LEDs with only one GaN barrier because of the enhancement in hole injection into the quantum well and decrease in electron leakage current. [ABSTRACT FROM AUTHOR]