High Performance of Zero-Power-Consumption MOCVD-Grown ß-Ga2O3-Based Solar-Blind Photodetectors with Ultralow Dark Current and High-Temperature Functionalities.

In this article, we report on high-performance deep ultraviolet photodetectors (DUV PDs) fabricated on metal-organic chemical vapor deposition (MOCVD)-grown ß-Ga2O3 heteroepitaxy that exhibit stable operation up to 125 °C. The fabricated DUV PDs exhibit self-powered behavior with an ultralow dark current of 1.75 fA and a very high photo-to-dark-current ratio (PDCR) of the order of 105 at zero bias and >105 at higher biases of 5 and 10 V, which remains almost constant up to 125 °C. The high responsivity of 6.62 A/W is obtained at 10 V at room temperature (RT) under the weak illumination of 42.86 µW/cm2 of 260 nm wavelength. The detector shows very low noise equivalent power (NEP) of 5.74 × 10-14 and 1.03 × 10-16 W/Hz1/2 and ultrahigh detectivity of 5.51 × 1011 and 3.10 × 1014 Jones at 0 and 5 V, respectively, which shows its high detection sensitivity. The RT UV-visible (260:500 nm) rejection ratios of the order of 103 at zero bias and 105 at 5 V are obtained. These results demonstrate the potential of Ga2O3-based DUV PDs for solar-blind detection applications that require high-temperature robustness.

A GaSe/Si-based vertical 2D/3D heterojunction for high-performance self-driven photodetectors.

We report on the fabrication of a vertical 2D/3D heterojunction diode between gallium selenide (GaSe) and silicon (Si), and describe its photoresponse properties. Kelvin probe force microscopy (KPFM) has been employed to investigate the surface potentials of the GaSe/Si heterostructure, leading to the evaluation of the value of the conduction band offset at the heterostructure interface. The current-voltage measurements on the heterojunction device display a diode-like nature. This diode-like nature is attributed to the type-II band alignment that exists at the p-n interface. The key parameters of a photodetector, such as photoresponsivity, detectivity, and external quantum efficiency, have been calculated for the fabricated device and compared with those of other similar devices. The photodetection measurements of the GaSe/Si heterojunction diode show excellent performance of the device, with high photoresponsivity, detectivity, and EQE values of ∼2.8 × 103 A W-1, 6.2 × 1012 Jones, and 6011, respectively, at a biasing of -5 V. Even at zero biasing, a high photoresponsivity of 6 A W-1 was obtained, making it a self-powered device. Therefore, the GaSe/Si self-driven heterojunction diode has promising potential in the field of efficient optoelectronic devices.

Localized surface plasmon resonance-enhanced solar-blind Al0.4Ga0.6N MSM photodetectors exhibiting high-temperature robustness.

The appealing properties of tunable direct wide bandgap, high-temperature robustness and chemical hardness, make AlxGa1-xN a promising candidate for fabricating robust solar-blind photodetectors (PDs). In this work, we have utilized the optical phenomenon of localized surface plasmon resonance (LSPR) in metal nanoparticles (NPs) to significantly enhance the performance of solar-blind Al0.4Ga0.6N metal-semiconductor-metal PDs that exhibit high-temperature robustness. We demonstrate that the presence of palladium (Pd) NPs leads to a remarkable enhancement by nearly 600, 300, and 462%, respectively, in the photo-to-dark current ratio (PDCR), responsivity, and specific detectivity of the Al0.4Ga0.6N PD at the wavelength of 280 nm. Using the optical power density of only 32µW cm-2at -10 V, maximum values of ∼3 × 103, 2.7 AW-1, and 2.4 × 1013Jones are found for the PDCR, responsivity and specific detectivity, respectively. The experimental observations are supported by finite difference time domain simulations, which clearly indicate the presence of LSPR in Pd NPs decorated on the surface of Al0.4Ga0.6N. The mechanism behind the enhancement is investigated in detail, and is ascribed to the LSPR induced effects, namely, improved optical absorption, enhanced local electric field and LSPR sensitization effect. Moreover, the PD exhibits a stable operation up to 400 K, thereby exhibiting the high-temperature robustness desirable for commercial applications.

Effective Antimicrobial Activity of Green ZnO Nano Particles of Catharanthus roseus.

In the present study, zinc oxide nanoparticles (ZnO NPs) were synthesized using leaf extract of Catharanthus roseus (C. roseus) under different physical parameters. Biosynthesis of ZnO NPs was confirmed by UV-Visible spectrophotometer and further, characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray spectroscopy (EDX), Atomic Force Microscopy (AFM), Photoluminescence study and Dynamic Light Scattering (DLS). We have also confirmed that several physical parameters such as pH, temperature, concentration of metal ions and reaction time were able to regulate shape and size of synthesized ZnO NPs. XRD and TEM analysis provided the information about the average size and hexagonal morphology of ZnO NPs. FTIR spectra analysis suggested that phenolic compounds played crucial role in the biosynthesis of ZnO NPs. The significant antibacterial activity of ZnO NPs was observed against Staphylococcus aureus MTCC 9760 (S. aureus), Streptococcus pyogenes MTCC 1926 (S. pyogenes), Bacillus cereus MTCC 430 (B. cereus), Pseudomonas aeruginosa MTCC 424 (P. aeruginosa), Proteus mirabilis MTCC 3310 (P. mirabilis) and Escherichia coli MTCC 40 (E. coli). The synthesized ZnO NPs have shown antibacterial efficacy against both Gram-positive and Gram-negative pathogens. Synergistic effects of ZnO NPs and streptomycin showed increased efficacy as indicated by the increased zone of clearance in comparison to their individual effects (either ZnO NPs or streptomycin). Overall, the results elucidated a rapid, cost-effective, environmentally friendly and convenient method for ZnO NPs synthesis, which could be used as a potential antimicrobial agent against drug resistant microbes.

Microbiological study of khoa sold in Chambal region (Madhya Pradesh): A case study.

Present study was conducted to analyze bacterial contaminants /pathogens in Khoa samples sold in Chambal region of Madhya Pradesh. Total Fifty samples of Khoa were brought from different localities of Chambal region at random and processed. Bacterial colony counts were also performed. Staphylococcus species and Streptococcus species were the predominant isolates. The viable counts obtained ranged from 1.3sX10(4) to 2.1sX10(6) CFU/g. Contamination of Khoa by pathogenic bacteria could be an important factor of gastrointestinal infections including food poisoning and food borne illness. Adequate consumer protection can be achieved by measuring the microbiological data of product.