The r-B4C films investigated in this study were deposited for 180 minutes at 1300 °C, temperature ramped in H2 atmosphere. The temperature was monitored by a pyrometer (Heitronics KT81R), calibrated by a silicon melt test. The process pressure was maintained at 7000 Pa, controlled by a throttle valve on the process pump. The n-type doped, double-side polished 4H-SiC wafers with an offcut of +/-0.5° relative to the c-axis, were 500 µm thick and obtained from Wolfspeed Inc. The 4H-SiC (0001) side is chemical mechanical polished (CMP) while the 4H-SiC (0001 ̅ ) is mechanically polished. 10x10 mm² pieces were cut from the wafers. Before deposition, the substrates were cleaned in an ultrasonic bath with acetone and ethanol for 5 minutes each, followed by an oxidizing alkaline solution (25% ammonia solution, 48% hydrogen peroxide solution, and water in a 1:1:5 ratio, at 80°C for 5 minutes) followed by rinsing in deionized water and an oxidizing acidic solution (37% hydrochloric acid solution, 48% hydrogen peroxide, and water in a 1:1:6 ratio, at 80°C for 5 minutes), and a final rinse in deionized water. The two substrates were placed next to each other in the middle of the susceptor during the CVD experiment.