One-dimensional wurtzite InN nanowires and zincblende InN nanorods are prepared by chemical vapour deposition (CVD) method on natural cleavage plane (110) of GaAs. The growth direction of InN nanowires is [100], with wurtzite structure. The stable crystal structure of InN is wurtzite (w-InN), zincblende structure (z-InN) is only reported for 2D InN crystals before. However, in this work, the zincblende InN nanorods [011] are synthesized and characterized. The SEM and TEM images show that every nanorod shapes a conical tip, which can be explained by the anisotropy of growth process and the theory of Ehrlich-Schwoebel barrier.
AlN (aluminium nitride) films were prepared by metalorganic chemical vapor deposition (MOCVD) on c-plane sapphire (α-Al 2 O 3 ) substrates. By means of studying the traces of in-situ optical reflectivity, it was found that the AlN nucleation layer showed a specific (0001) lattice orientation, which differed from the GaN nucleation layer on (0001) sapphire substrates. The AlN buffer suffered the compressive stress at the initial stage of nucleation. And the compressive strain was relaxed gradually along with the thickness of buffer increasing and consequently annealing. Optical transmission spectra revealed that in the process of growing AlN epilayers, higher V/III ratio could improve the crystal quality but reduce the growth rates. In addition, proper doping of silane (SiH 4 ) could improve the surface morphology of AlN film.AlN, MOCVD, optical reflectivity, XRD, optical transmission spectra As a wide band gap semiconductor material, AlN has great potential for applications in ultraviolet (UV) light emitting diodes (LEDs) and laser diodes (LDs), high temperature/frequency electronic devices, and GHz-band surface acoustic wave (SAW) devices. Therefore, a great interest in the preparation of high quality single-crystal AlN film has arisen recently. Today, methods for preparing AlN film include plused-laser deposition (PLD), rf sputtering, molecular beam epitaxy (MBE), and metalorganic chemical vapor deposition (MOCVD). However, high quality of AlN films are hard to obtain due to low diffusion velocity of adsorbed Al atoms and intense parasitic reactions during the high temperature growth [1][2][3] .In this paper, we deposited AlN film on c-plane sapphire substrates using the two-step method by MOCVD. The evolution of nucleation and stress of AlN buffer layer was analyzed. Furthermore, the influences of Si doping and V/III ratio to the quality of AlN film were studied.
Aluminum gallium indium nitride(AlGaInN) quaternary epilayers were prepared by metalorganic chemical vapor deposition (MOCVD) on c-plane sapphire (α-Al2O3) substrates. Three samples were grown under different temperatures of 800 ℃,850 ℃ and 900 ℃. It is found that the In composition monotonically decreases with the increasing growth temperature,while the Al composition is nearly invariable. The V-pits appeared when the growth temperature increases to 850 ℃, and the size and density of V-pits drastically decrease and the nucleation of V-pits is passivated when the growth temperature rises to 900 ℃ due to the desorption enhancement of segregated In atoms.
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