During our research, we explored a novel way to represent subwavelength imaging and derived a transmission equation to explicate the FP (Fabry–Pérot) resonance phenomena. Subsequently, using analysis and observation, we performed deep-subwavelength imaging. Both numerically and experimentally, imaging with super-resolution was achieved at deep subwavelength scale of λ/56.53 with a lens thickness 212 mm. Our results also showed that by increasing lens thickness, higher resolution can be achieved. Moreover, via a single source study, we showed the full width at half maximum range and predicted the size of smallest detectable object. We also observed that with a greater lens thickness, finer features could be detected. These findings may open a new route in near-field imaging for practical applications such as biometric sensors, ultrasonic medical equipment, and non-destructive testing.

Efficient beam steering using elements in the subwavelength scale is an exciting field, which can significantly miniaturize the existing acoustic systems and may lead to promising applications of sonic devices. In this study, we build an acoustic metasurface, which functions as a holographic leaky wave antenna and achieves effective beam steering in the designed direction. It is demonstrated that carefully designing the depth of the cylindrically grooved elements, arranged in a hexagonal pattern, allows the refractive index and surface admittance to be manipulated and can be used to generate acoustic surface modes below the cutoff frequency. The hologram principle, originally used for holographic reactance surfaces in the electromagnetic regime, is used to introduce admittance patterns, which allow effective beam steering results. We present a detailed construction methodology of the holographic acoustic admittance surface and verify its beam steering effectiveness both experimentally and numerically. The present work presents an effective method for acoustic beam steering and brings us one step closer in achieving freely steering wave beams.

We report new frequency bands for subwavelength imaging by using the resonant tunneling method which have not been explored previously. As per the existing theory of resonant tunneling, imaging frequency is limited for a certain number of crystals. However, after conducting an analytical analysis over a wide range of frequencies, we observed that higher frequencies do exist for subwavelength imaging. We verified this observation both numerically and experimentally. We extended our study to observe the effect of lattice periodicity on image resolution. By reducing periodicity during experiment, we achieved a resolution of λ/9.5 at the conventional region and λ/2.45 at the higher band region.

Organic materials are now being used in a wide range of microelectronic applications in parallel with inorganic materials, because of their superior properties, environmental safety, and low cost. This paper describes the characterization of Aloe vera gel (AVG), a new organic dielectric material. The surface morphology, spatial distribution of elements, and structural characteristics of an AVG layer were examined using scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD), respectively. The resistance of the AVG layer, determined using a four-probe station, was 640 Ω. EDX showed that the elements contained in the layer were carbon, oxygen, aluminum, silicon, calcium, potassium, and copper. The XRD results suggested that the sample primarily consisted of bornite (Cu 5 FeS 4 ), geerite (Cu 8 S 5 ), sal ammoniac (NH 4 Cl), and carobbite (KF).

The parameters of crystalline semiconductor such as types of semiconductor, uniformity of impurity concentration of doped wafer, majority charge carrier concentration, sheet resistivity of doped wafer surface play an important role in solar cell fabrication process during emitter diffusion, that is the most critical step. In this paper, we have used a low cost in house made hot probe measurement setup. A hot plate was used to heat up the wafer up to 100°C. Two k-type thermocouples were placed simultaneously in contact with the hot and cold surface of the wafer to measure the temperature in situ for both hot and cold probe. We have used two copper probes with a voltmeter connected to measure the potential difference (thermoelectric voltage) between two probes for various temperatures up to 100°C with an interval of 10°C. We have taken measurement for commercial silicon wafer (thickness 200 µm) and one side polished 4 inch diameter Si wafer (thickness 660 µm) to determine the wafer type (n-type or p-type). We also calculated thermopower or Seebeck coefficient from the voltage vs. time curve, that is constant for particular substrate. As a process monitoring tool for solar cell fabrication process, after n-type diffusion using POCl3 on p-type silicon wafer of thickness 200 µm, we have done wafer mapping that gives us the information of doping uniformity over the whole surface of wafer both front and back side

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Utilizing acoustic metasurfaces consisting of subwavelength resonant textures, we design an artificial impedance surface by creating a new boundary condition. We demonstrate a circular artificial impedance surface with surface impedance modulation for directional sound beamforming in three-dimensional space. This artificial impedance surface is implemented by revolving two-dimensional Helmholtz resonators with varying internal coiled path. Physically, the textured surface has inductive surface impedance on its inner circular patterns and capacitive surface impedance on its outer circular patterns. Directional receive beamforming can be achieved using an omnidirectional microphone located at the focal point formed by the gradient-impeding surface. In addition, the uniaxial surface impedance patterning inside the circular aperture can be used for steering the direction of the main lobe of the radiation pattern.