Fig shows the thicknesses of three

Experimental
Film growth was performed in a custom built MBE chamber. This chamber exhibited a background pressure of 3.1×10−9 Torr during the time prior to sample growth. Samples are thermally heated by radiative transfer from a pyrolytic boron nitride (PBN) heater plate 5 mm offset from the back of the wafer. Samples are rotated during growth at 5 rpm to promote film uniformity.