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Dielectric REduced SURface Field (RESURF) is a promising concept to enhance the breakdown voltage of power semiconductor devices. This letter reports a set of simple and unified analytical equations to calculate the breakdown voltage, critical electric field, and depletion widths for dielectric RESURF p-n junctions. These analytical models are derived from the basic power law relationship between the p-n junction breakdown voltage and doping concentration, and use the material and structural information of the dielectric RESURF p-n junction as variables to accurately predict reverse bias performance. The analytically calculated results are compared with 2D TCAD simulation results for Si, GaN, and SiC in combination with dielectrics, such as SiO2 and Si3N4, and show reasonable agreement well within 10% of error.

A comprehensive description of a procedure to form dense locally ordered 2D arrays of vertically aligned hexagonal in section GaN nanocolumns (NCs) without height deviations will be presented. Particular focus will be given for the preparation of silica nanosphere hard masks, dry etching to form GaN NCs, wet etching to modify NC shape, thermal annealing and regrowth to recover non-polar m-plane facets, improve NC crystal quality and array fill factor.

Design considerations for vertical Gallium Nitride (GaN) nanowire Schottky barrier diodes (NWSBDs) for high voltage applications is discussed in this paper. Preliminary quasi-vertical NWSBDs fabricated on a Sapphire substrate show rectifying properties with breakdown voltage of 100 V. The principle of dielectric Reduced SURface Field (RESURF) which is naturally compatible with the NW structure, is utilized to block high voltages (> 600 V) within the fabrication constraints of nano-pillar height and drift doping concentration. Design considerations for the NWSBD is explored through 3D TCAD simulations. TCAD simulations show the NWSBDs can block voltages upward of 700 V with very low on-resistance with optimal design. The measured and simulated results are compared with state of the art GaN devices to provide an understanding of the true potential of the GaN NW architecture as power devices offering high breakdown voltages and low on-state resistance and a reliable device operation, all on a vertical architecture and a non-native substrate.

A new concept of vertical gallium nitride (GaN) Schottky barrier diode based on nanowire (NW) structures and the principle of dielectric REduced SURface Field (RESURF) is proposed in this paper. High-threading dislocation density in GaN epitaxy grown on foreign substrates has hindered the development and commercialization of vertical GaN power devices. The proposed NW structure, previously explored for LEDs offers an opportunity to reduce defect density and fabricate low cost vertical GaN power devices on silicon (Si) substrates. In this paper, we investigate the static characteristics of high-voltage GaN NW Schottky diodes using 3-D TCAD device simulation. The NW architecture theoretically achieves blocking voltages upward of 700 V with very low specific on-resistance. Two different methods of device fabrication are discussed. Preliminary experimental results are reported on device samples fabricated using one of the proposed methods. The fabricated Schottky diodes exhibit a breakdown voltage of around 100 V and no signs of current collapse. Although more work is needed to further explore the nano-GaN concept, the preliminary results indicate that superior tradeoff between the breakdown voltage and specific on-resistance can be achieved, all on a vertical architecture and a foreign substrate. The proposed NW approach has the potential to deliver low cost reliable GaN power devices, circumventing the limitations of today's high electron mobility transistors (HEMTs) technology and vertical GaN on GaN devices.

Bulk gallium nitride (GaN) power semiconductor devices are gaining significant interest in recent years, creating the need for technology computer aided design (TCAD) simulation to accurately model and optimize these devices. This paper comprehensively reviews and compares different GaN physical models and model parameters in the literature, and discusses the appropriate selection of these models and parameters for TCAD simulation. 2-D drift-diffusion semi-classical simulation is carried out for 2.6 kV and 3.7 kV bulk GaN vertical PN diodes. The simulated forward current-voltage and reverse breakdown characteristics are in good agreement with the measurement data even over a wide temperature range.