Quantum well width and barrier thickness effects on the perpendicular transport in polar and non-polar oriented AlGaN/GaN Resonant Tunneling Diodes

International audienceIn this study, we theoretically investigated the electronic properties of resonant tunneling diodes (RTDs) grown along the polar and non-polar orientations by using the self-consistent solution of the coupled Schrödinger and Poisson equations. Based on the transfer matrix formalism, the effects of the geometrical parameters on the current-voltage characteristics of Al0.2Ga0.8N/GaN RTDs we analyzed by varying GaN well width and Al0.2Ga0.8N/GaN barrier thicknesses. The results show that the characteristics of polar and nonpolar Al0.2Ga0.8 N/GaN RTD strongly depend on the barrier and well size; showing a strong decrease in peak and valley current density and a large PVR enhancement when increasing well and barrier thickness. To bring interesting RTD electrical characteristics, a comparison between the polar and non-polar Al0.2 Ga0.8N/GaN RTD was performed. non-polar oriented RTDs show better electronic characteristics, including higher peak current density (Jpeak), smaller peak voltage (Vpeak), and greater pic-to-valley ratio (PVR), than polar ones

Design of elliptical photonic crystal fiber (E-PCF) for the transmission of 116 OAM channels across the S, C, L and U bands

Orbital angular momentum (OAM) modes over photonic crystal fibers (PCFs) have shown great capability in unleashing the available data rates in optical communication systems. In this paper, we propose and numerically design a novel elliptical photonic crystal fiber (E-PCF) using assisted Germania-doped silica as a material background and elliptical air holes. Using a systematic scanning methodology, we adjusted the E-PCF key parameters with the aim to explore appropriate designs that support large number of OAM channels featuring low confinement loss (CL). Numerical simulations using finite element method (FEM) show the supports of large number of independent/separate OAM channels (116 OAM with Δneff≥ 10−4). A detailed numerical modal analysis has been carried out over the S + C + L + U communication bands show that the designed E-PCF handles robust OAM modes. This includes low chromatic dispersion (CD = 92 ps/km/nm), low differential group delay (<60 ps/km), high effective mode area (max Aeff = 124 µm2), low nonlinearity coefficient (γ < 2.6 /W/m) and low confinement loss (Max CL = 2.07 × 10−4 dB/m). The obtained results and the comparisons with those recently reported in literature shows that the designed E-PCF could find applications in next-generation optical communication systems that uses OAM modes as data carriers