SiC nanowires are grown by a novel catalyst-assisted sublimation-sandwich method. This involves microwave heating-assisted physical vapor transport from a "source" 4H-SiC wafer to a closely positioned "substrate" 4H-SiC wafer. The "substrate wafer" is coated with a group VIII (Fe, Ni, Pd, Pt) metal catalyst film about 5 nm thick. The nanowire growth is performed in a nitrogen atmosphere, in the temperature range of 1650-1750 °C for 40 s durations. The nanowires grow by the vapor-liquid-solid (VLS) mechanism facilitated by metal catalyst islands that form on the substrate wafer surface at the growth temperatures used in this work. The nanowires are 10-30 µm long. Electron backscatter diffraction (EBSD) and selected area electron diffraction analyses confirm the nanowires to crystallize with a cubic 3C structure of 3C-SiC. EBSD from the nanowire caps are indexed as Fe 2 Si, Ni 3 Si, Pd 2 Si, and PtSi phases for the nanowires grown using Fe, Ni, Pd, and Pt as the metal catalysts, respectively. The nanowires are found to grow along the 〈112〉 directions, as opposed to the commonly observed 〈111〉 directions. The micro-Raman spectra from single nanowires indicate regions with varying compressive strain in the nanowires and also show modes not arising from the Brillouin zone center, which may indicate the presence of defects in the nanowire.

An ultrafast microwave annealing method, different from conventional thermal annealing, is used to activate Mg-implants in GaN layer. The x-ray diffraction measurements indicated complete disappearance of the defect sublattice peak, introduced by the implantation process for single-energy Mg-implantation, when the annealing was performed at Ն1400°C for 15 s. An increase in the intensity of Mg-acceptor related luminescence peak ͑at 3.26 eV͒ in the photoluminescence spectra confirms the Mg-acceptor activation in single-energy Mg-implanted GaN. In case of multiple-energy implantation, the implant generated defects persisted even after 1500°C / 15 s annealing, resulting in no net Mg-acceptor activation of the Mg-implant. The Mg-implant is relatively thermally stable and the sample surface roughness is 6 nm after 1500°C / 15 s annealing, using a 600 nm thick AlN cap. In situ Be-doped GaN films, after 1300°C / 5 s annealing have shown Be out-diffusion into the AlN layer and also in-diffusion toward the GaN/SiC interface. The in-diffusion and out-diffusion of the Be increased with increasing annealing temperature. In fact, after 1500°C / 5 s annealing, only a small fraction of in situ doped Be remained in the GaN layer, revealing the inadequateness of using Be-implantation for forming p-type doped layers in the GaN.

In this work, an ultrafast solid-state microwave annealing has been performed, in the temperature range of 1700–2120°C on Al+- and P+-implanted 4H-SiC. The solid-state microwave system used in this study is capable of raising the SiC sample temperatures to extremely high values, at heating rates of ∼600°C∕s. The samples were annealed for 5–60s in a pure nitrogen ambient. Atomic force microscopy performed on the annealed samples indicated a smooth surface with a rms roughness of 1.4nm for 5×5μm2 scans even for microwave annealing at 2050°C for 30s. Auger sputter profiling revealed a <7nm thick surface layer composed primarily of silicon, oxygen, and nitrogen for the samples annealed in N2, at annealing temperatures up to 2100°C. X-ray photoelectron spectroscopy revealed that this surface layer is mainly composed of silicon oxide and silicon nitride. Secondary ion mass spectrometry depth profiling confirmed almost no dopant in diffusion after microwave annealing at 2100°C for 15s. However, a sublimation of ∼100nm of the surface SiC layer was observed for 15s annealing at 2100°C. Rutherford backscattering spectra revealed a lattice damage-free SiC material after microwave annealing at 2050°C for 15s, with scattering yields near the virgin SiC material. Van der Pauw–Hall measurements have revealed sheet resistance values as low as 2.4kΩ∕◻ for Al+-implanted material annealed at 2100°C for 15s and 14Ω∕◻ for the P+-implanted material annealed at 1950°C for 30s. The highest electron and hole mobilities measured in this work were 100 and 6.8cm2∕Vs, respectively, for the P+- and Al+-implanted materials.

A microwave heating technique has been used for the electrical activation of Al+ ions implanted in semi-insulating 4H-SiC. Annealing temperatures in the range of 2000–2100 °C and annealing time of 30 s have been used. The implanted Al concentration has been varied from 5×1019 to 8×1020 cm-3. A minimum resistivity of 2×10-2 Ω·cm and about 70% electrical activation of the implanted Al have been measured at room temperature for an implanted Al concentration of 8×1020 cm-3 and microwave annealing at 2100 °C for 30 s