Abstract
We have studied the effect of AlN buffer layers, having variable thicknesses in situ grown by rf-magnetron sputtering, on the structural and vibration dynamic properties of AlInN thin films grown by dc-magnetron sputtering on Si(0 0 1) substrates at 700 °C. X-ray diffraction patterns reveal that an increase in thickness of the AlN buffer layer can significantly promote the textured growth orientation of AlInN(0 0 0 2)//Si(0 0 1) and improve the grain sizes of AlInN. They also reveal that the Al composition in the resultant AlInN thin film increases with the thickness of AlN; however, phase separations, which are usually observed in metal-organic chemical vapour deposition (MOCVD) growth of AlInN with similar Al compositions, are not detectable. Instead, uniform element distribution profiles along the growth direction of AlInN are detected by secondary ion-mass spectroscopy. Micro-Raman scattering spectra collected at room temperature exhibit three optical phonon features from the AlInN thin films, which, in terms of their evolutions with Al composition, can be assigned to AlInN , InN-like A1(LO), and AlN-like A1(LO), respectively, consistent with that recently observed in MOCVD grown In-rich AlInN. The solar cell based on n-AlInN/AlN/p-Si exhibits a typical diode-like dark I-V curve; however, its photocarrier collection is apparently suppressed due to the polarization charges at the junction interfaces.