Effect of Scandium Nitride Film Orientation on Growth and Electrical Properties*

Scandium nitride (ScN) is a rock-salt semiconductor with potential as a complimentary material to enhance gallium nitride (GaN) performance in high-power and high-speed electronic applications. Electron mobilities as high as 130 cm²/(V*s) have been reported for (100)-ScN on (100)-magnesium oxide (MgO) substrates. The values reported for (111)-ScN on GaN or sapphire, however, are significantly lower. The mechanism responsible for the poorer transport properties of (111)-ScN has not to date been identified. In this work, we investigate the effect of ScN orientation on film growth, composition and electrical properties. A series of thin ScN films were deposited on (111)-, (110)- and (100)-MgO substrates using reactive magnetron sputtering. X-ray diffraction and atomic force microscopy showed that ScN crystallinity and surface morphology were dependent on the MgO substrate. Secondary ion mass spectroscopy showed negligible differences in oxygen concentration but variation in fluorine and hydrogen concentrations. Temperature-dependent Hall-effect measurements showed that ScN electrical properties were dependent on film orientation.