4H-SiC Power Metal–Oxide–Semiconductor Field Effect Transistors and Schottky Barrier Diodes of 1.7 kV Rating

Abstract

We present an atomistic model of interface alloying that presupposes exchange of adatoms with substrate atoms and floating of adatoms on the upper layers during deposition. Due to the existence of a preferred direction (the growth direction), the chemical profile near the interface proves to be asymmetrical. The floating algorithm combined with self-consistent calculations of atomic magnetic moments is used as a model for interpreting Mössbauer data obtained from 57 Fe-enriched interfacial tracer layers in Fe/Cr(001) superlattices. The superlattices were grown at different temperatures in order to modify their interface roughness. A linear correlation between calculated moment peaks and observed distinct magnetic hyperfine fields was found. Our experimental samples exhibit larger intermixing than the simplified theoretical model we used. The experimental giant magnetoresistance ratio was observed to increase with the decreasing fraction of certain 57 Fe atoms located in the interfacial region. Therefore, bulk scattering from impurity atoms appears to provide the main contribution to the giant magnetoresistance in Fe/Cr. Moreover, our theoretical results clarify the dependence of the short-wavelength period of interlayer coupling on the interface roughness in Fe/Cr.

Extremely Low On-Resistance and High Breakdown Voltage Observed in Vertical GaN Schottky Barrier Diodes with High-Mobility Drift Layers on Low-Dislocation-Density GaN Substrates

“…Figure 7 presents the V B -R on A relations 11) for the fabricated SBD together with previous results. 12,13) The figure of merit (V B 2 =R on A) was calculated to be 1.7 GW/cm 2 , which is the highest value among previously reported vertical SBDs for both GaN and SiC. This extremely low specific on-resistance of 0.71 m cm 2 has been realized by utilizing the high electron mobility in the high quality n-GaN layer grown on freestanding GaN substrate.…”

Impacts of surface C/Si ratio on in-wafer uniformity and defect density of 4H-SiC homo-epitaxial films grown by high-speed wafer rotation vertical CVD

“…It is expected that 4H-SiC will be a material for achieving power devices that operate under high current density and high voltage, because of its excellent physical properties such as wide band gap, high thermal conductivity and high breakdown electric field. Schottky barrier diodes [1][2][3] and metal-oxide-semiconductor field-effect transistors [2][3][4][5] based on 4H-SiC, which have high breakdown voltage around 0.6-1.7 kV, have already been put to practical use. In order to realize power devices operated under higher current density and higher voltage, bipolar devices in which lower onresistance can be achieved by conductivity modulation are also studied all over the world.…”

Influence of residual dopants to net doping concentration in N-type 4H-SiC films grown using high-speed wafer rotation vertical CVD method

“…4H-SiC is expected to be used for achieving high-efficiency power devices operating under high current density and high voltage owing to its excellent physical properties such as wide band gap, high thermal conductivity, and high breakdown electric field. Schottky barrier diodes (SBDs) [1][2][3] and metaloxide-semiconductor field-effect transistors (MOSFETs) [2][3][4][5] based on 4H-SiC, which have a high breakdown voltage of approximately 0.6-3.3 kV, have already been put or are close to practical use. To realize power devices operating under ultra-high power density, a drift layer comprising n-type 4H-SiC films with thicknesses greater than 100 μm and doping concentrations lower than 1 × 10 15 cm −3 is required.…”