Abstract:

Two-inch semi-insulating SiC bulk crystals with resistivity higher than 1×10⁶ ­Ωcm were achieved by vanadium doping during sublimation. Secondary-ion-mass-spectrometry (SIMS) was employed to determine the concen- tration of impurities in the crystals, such as B, Al, V and N. These results indicated that the concentration of nitrogen and aluminum kept on decreasing and the concentration of B and V was almost constant during the whole growth. An inner crucible was used to control the exhausting of vanadium, which made the uniformity of the high resistivity (>1×10⁶ ­Ωcm) in the wafer up to 80%. High-performance AlGaN/GaN high-electron- mobility-transistor (HEMT) materials and devices were grown and fabricated on semi-insulating 6H-SiC sub- strates. The two-dimensional electron gas (2DEG) mobility at room-temperature was 1795 cm²/V•s. The charge carrier concentration of the substrate determined by capacitance-voltage (C-V) test was 7.3×10¹⁵ Ωcm⁻³. The device with a gate width of 1 mm exhibits a maximum output power of 5.5 W at 8 GHz, which proves the semi-insulating property of the substrates indirectly.

Key words: Silicon Carbide, Semi-insulating, Vanadium-doped, AlGaN/GaN HEMT