Analysis of Wide-Bandgap Material OPFET UV Detectors for High Dynamic Range Imaging and Communication Applications

The ultraviolet (UV) photoresponses of Wurtzite GaN, ZnO, and 6H-SiC-based Optical Field Effect Transistor (OPFET) detectors are estimated with an in-depth analysis of the same considering the generalized model and the front-illuminated model for high resolution imaging and UV communication applications. The gate materials considered for the proposed study are gold (Au) and Indium-Tin-Oxide (ITO) for GaN, Au for SiC, and Au and silver dioxide (AgO2) for ZnO. The results indicate significant improvement in the Linear Dynamic Range (LDR) over the previously investigated GaN OPFET (buried-gate, front-illuminated and generalized) models with Au gate. The generalized model has superior dynamic range than the front-illuminated model. In terms of responsivity, all the models including buried-gate OPFET exhibit high and comparable photoresponses. Buried-gate devices on the whole, exhibit faster response than the surface gate models except in the AgO2-ZnO generalized OPFET model wherein the switching time is the lowest. The generalized model enables faster switching than the front-illuminated model. The switching times in all the cases are of the order of nanoseconds to picoseconds. The SiC generalized OPFET model shows the highest 3-dB bandwidths of 11.88 GHz, 36.2 GHz, and 364 GHz, and modest unity-gain cut-off frequencies of 4.62 GHz, 8.71 GHz, and 5.71 GHz at the optical power densities of 0.575 μW/cm2, 0.575 mW/cm2, and 0.575 W/cm2 respectively. These are in overall, the highest detection-cum-amplifi-cation bandwidths among all the investigated devices. The same device exhibits the highest LDR of 73.3 dB. The device performance is superior to most of the other existing detectors along with comparable LDR, thus, emerging as a high performance photodetector for imaging and communication applications. All the detectors show considerably high detectivities owing to the high responsivity values. The results have been analyzed by the photovoltaic and the photoconductive effects, and the series resistance effects and will aid in conducting further research. The results are in line with the experiments and the commercially available software simulations. The devices will greatly contribute towards single photon counting, high resolution imaging, and UV communication applications.

Edge Port Excited Metamaterial Based Patch Antennas for 5G Application

Microstrip Patch Antenna is a narrowband antenna fabricated by etching the antenna element pattern in metal trace of elements like copper bonded to an insulating dielectric substrate with a continuous metal layer on the opposite side of the substrate which forms a ground plane. Electromagnetic Metamaterial is an artificial material that is made up of different types of structural designs on dielectric substrates. In this paper, a broad and elite investigation is being carried out by designing and simulating a single negative metamaterial cell comprising a square split ring resonator. This metamaterial cell depicts negative values of permeability for a specific range of frequencies. These cells show exceptionally great applications in the design of microstrip patch antenna. The substrate of the microstrip patch antenna with a ground plane is loaded with a square split-ring resonator, Conventional and proposed patch antennas are simulated, analyzed, and reported for performance comparison of its parameters. The proposed edge port feed metamaterial based Rectangular microstrip patch antenna and Circular patch antenna designed at 26 GHz resonance frequency useful for 5G applications. Both antennas are designed on RT Duroid 5880 Substrate with 2.2, dielectric constants. The parameters such as bandwidth, gain and return loss of metamaterial loaded rectangular microstrip patch antenna and Circular patch antenna increases considerably compared to conventional antennas. Comparing parameters of both antennas, the performance of the rectangular microstrip patch antenna is found to be better than circular patch antenna.