Electron-beam-induced carbon deposition on high-indium-content AlInN thin films grown on Si by sputtering at elevated temperature

We report on unintentional carbon depositions induced by electron-beam irradiation on the surface of high-indium-content AlInN thin films in a scanning-electron microscope (SEM) chamber. With a beam voltage of 10 kV and a probe current of 160 µA, a nano-scale dot evolves during a 5-min irradiation. By increasing the irradiation time, the dot grows in diameter and height. The dot size when compared with that grown on a Si substrate under the same conditions is much smaller. Energy-dispersive X-ray spectroscopy reveals a linear increase in carbon deposition as a function of irradiation time and the rate of increase is larger on AlInN than that on Si. These observations, together with the remarkable morphology evolutions around the dot on AlInN rather than on Si, provide evidence that the surface mobility of the adsorbed molecules is larger on Si than that on AlInN. The reduced surface mobility on AlInN is attributed to surface roughness, the existence of an electron accumulation layer, and columnar grain structures of the AlInN layer. These properties can be used to benefit the fabrication of small structures on the AlInN surface without affecting the surroundings.