Elaboration and characterization of boron doping during SiC growth by VLS mechanism

VLS mechanism was used for growing boron doped homoepitaxial SiC layers on 4H-SiC(0 0 0 1) 8° off substrate. Si-based melts were fed by propane in the temperature range 1450–1500 °C. Two main approaches were studied to incorporate boron during growth: (1) adding elemental B in the initial melt, with two different compositions: Si90B10 and Si27Ge68B5; the growth was performed at 1500 °C; (2) adding B2H6 to the gas phase during growth with a melt composition of Si25Ge75; the growth was performed at 1450 °C. In most cases, the growth time was limited by liquid loss. The longest growth duration (1 h) was obtained when adding B2H6 to the gas phase. In the case of Si90B10 melt, the surface morphology exhibits large and parallel terraces whereas the step front is more undulated when adding Ge. Raman and photoluminescence characterizations performed on these layers confirmed the 4H polytype of the layers in addition to the presence of B, which results in a strong B–N donor–acceptor band. The thickness and the growth rate were determined by micro-Infrared spectroscopy. Particle Induced γ-ray Emission (PIGE) was tentatively used to detect B incorporation inside the grown layers. These results were compared to SIMS measurements from which B concentration was found to vary from 1018 to 1019 at cm−3.

► Boron doped homoepitaxial SiC layers was grow by VLS mechanism.
► Adding B in the melt and in the gas phase is the two approaches to incorporate B.
► The growth times is limited by liquid losses.
► Increasing boron in the melt increasing boron in the layers.