Effect of thermal annealing on the defects and electrical properties of semi-insulating 6H-SiC

Abstract Vanadium-doped 6H-SiC wafers were annealed at 950°C, 1350°C and 1650°C in argon atmosphere for 1h in order to investigate the thermal annealing effect on the defects and electrical properties. It was experimentally observed that the electrical and crystalline property of vanadium-doped 6H-SiC didn’t obviously change after annealing at 950°C and 1350°C. However, the resistivity of vanadium-doped 6H-SiC dropped by 5-6 orders of magnitude after annealing at 1650°C. The glow discharge mass spectrometry (GDMS), electron paramagnetic resonance (EPR), high resolution x-ray diffraction (HRXRD) and resistivity mapping measurements implied that both vanadium dopants and intrinsic defects were responsible for the semi-insulating property of the as-grown single crystal SiC. After annealing at high temperature (≥1650°C), the doped vanadium in single crystal SiC would partially evaporate and the left vanadium dopants might be not enough to compensate the unintentional donors/acceptors with the disappearance of silicon vacancy defects.