Effect of In/Al ratios on structural and optical properties of InAlN films grown on Si(100) by RF-MOMBE

In( x )Al(1-x )N films were deposited on Si(100) substrate using metal-organic molecular beam epitaxy. We investigated the effect of the trimethylindium/trimethylaluminum (TMIn/TMAl) flow ratios on the structural, morphological, and optical properties of In( x )Al(1-x )N films. Surface morphologies and microstructure of the In( x )Al(1-x )N films were measured by atomic force microscopy, scanning electron microscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM), respectively. Optical properties of all films were evaluated using an ultraviolet/visible/infrared (UV/Vis/IR) reflection spectrophotometer. XRD and TEM results indicated that In( x )Al(1-x )N films were preferentially oriented in the c-axis direction. Besides, the growth rates of In( x )Al(1-x )N films were measured at around 0.6 μm/h in average. Reflection spectrum shows that the optical absorption of the In( x )Al(1-x )N films redshifts with an increase in the In composition.