SiC 4H: December 2018

Dec 24, 2018

Fully implanted vertical p–i–n diodes using high-purity semi-insulating 4H–SiC wafers

The fabrication of a fully ion-implanted vertical p–i–n diode using high-purity semi-insulating 4H–SiC substrate has been demonstrated for the first time. The intrinsic region is the wafer itself with a thickness of 350 µm. The anode and cathode are obtained by doping the front and back wafer surfaces with implanted Al+ and P+ ions, respectively, with concentrations of about 1020 cm−3. The electrical activation of the implanted dopants is obtained by microwave heating the samples up to 2100 °C for 30 s. At ±100 V the on and off state current ratio is in the order of 104. Forward saturation current is five orders larger than it would be if controlled by the series resistance of the thick HPSI 4H–SiC intrinsic region.

Source:IOPscience

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Dec 10, 2018

Determination of the transport properties in 4H-SiC wafers by Raman scattering measurement

The free carrier density and mobility in n-type 4H-SiC substrates and epilayers were determined by accurately analysing the frequency shift and the full-shape of the longitudinal optic phonon—plasmon coupled (LOPC) modes, and compared with those determined by Hall-effect measurement and that provided by the vendors. The transport properties of thick and thin 4H-SiC epilayers grown in both vertical and horizontal reactors were also studied. The free carrier density ranges between 2×1018 cm−3 and 8×1018 cm−3 with a carrier mobility of 30–55 cm2/(Vcenterdots) for n-type 4H-SiC substrates and 1× 1016−3×1016 cm−3 with mobility of 290–490 cm2/(Vcenterdots) for both thick and thin 4H-SiC epilayers grown in a horizontal reactor, while thick 4H-SiC epilayers grown in vertical reactor have a slightly higher carrier concentration of around 8.1×1016 cm−3 with mobility of 380 cm2/(Vcenterdots). It was shown that Raman spectroscopy is a potential technique for determining the transport properties of 4H-SiC wafers with the advantage of being able to probe very small volumes and also being non-destructive. This is especially useful for future mass production of 4H-SiC epi-wafers.