Structural and Raman properties of compositionally tunable Al_xGa_(1-x)N (0.66 ≤ x≤ 1) nanowires

摘要

In this work, we describe compositionally tunable Al_xGa_(1-x)N nanowires (0.66 ≤ x ≤ 1) grown on Si (100) substrates using a chemical vapor deposition (CVD) process. The composition of Al_xGa_(1-x)N nanowires may be tuned by adjusting the vapor temperature of the AlCl_3 and GaCl_3 used in its production. The structural, chemical and optical properties of the Al_xGa_(1-x)N nanowires are investigated using X-ray diffractometry (XRD),field emission scanningelectron microscopy (FESEM),X-ray energy-dispersive spectroscopy(EDS), transmission electron microscopy (TEM) and Raman spectroscopy. All the Al_xGa_(1-x)N nanowires exhibit a preferred c-axis orientation. Raman analysis shows that the E_2~2 phonon exhibits two-mode behavior. The positions of the AIN-like E_2~2, GaN-like E_2~2 and A_1 (TO) modes shift toward higher frequencies as the amount of Al increases. The growth of these Al_xGa_(1-x)N nanowires has been proposed to follow a vapor-solid-solid (VSS) mechanism.