Fabrication of AlN single crystal particles by a chemical vapor method using aluminum chloride

Abstract

The synthesis of single crystal AlN particles has been carried out by the chemical vapor method using AlCl3 and NH3 as sources at 1450 °C. The x‐ray diffraction (XRD) measurement reveals that the samples are AlN in the wurtzite structure. The XRD line width had its minimum around partial pressure of NH3 (P (NH3)) of 0.25 atm, indicating the highest crystal quality among the samples synthesized in this study. The powders prepared at P (NH3) between 0.13 and 0.38 atm consisted mostly of particles with sizes ranging between approximately 100 and 500 nm. The particles in these samples had specific shapes with a sixfold symmetry reflecting the wurtzite crystal structure of AlN. The observation of particle morphology has also suggested that the particles composed of two crystal grains are included in the samples. The mechanism of particle formation was discussed based on the dependence of particle morphology on P (NH3). Comparison with the synthesis using vaporized Al as an Al source leads us to conclude that the use of AlCl3 is essential to the efficient formation of single crystal particles. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Low-Temperature Synthesis of Aluminum Nitride by Addition of Ammonium Chloride

“…However, although the addition of boric acid is suitable for the synthesis of AlN for refractory applications, it is unsuitable for synthesizing a sealing material for use in electronic and optical devices because boron nitride remains in the prepared AlN. In the CVD method, AlCl 3 is nitrided with nitrogen gas or ammonia gas at 650–750 °C to obtain AlN, but precise control is required, such as vacuum conditions. − On the other hand, in the direct nitridation method, a sample prepared by adding alkali fluoride, alkali chloride, or sodium nitrite to Al powder is heated at 650 °C, which is slightly lower than the melting point of aluminum, and then the nitridation of aluminum is conducted by increasing the heating temperature. − Selvaduray and Sheet performed the latter heating stage at 1600 °C for stabilization. Qiu and Gao , reported that the addition of KCl and NH 4 Cl lowered the nitridation temperature, and the diffusion of NH 3 gas into the solid was accelerated by the generation of voids formed by the volatilization of KCl.…”

Strong light coupling effect for a glancing-deposited silver nanorod array in the Kretschmann configuration

“…For a metal nanostructure, some of the energy of incident light is used in extinction, including absorption and scattering, and some is used in transmission and reflection. Recently, optical scattering from metallic nanoparticles has been applied in bio-sensing, such as in surface-enhanced Raman scattering (SERS) [ 4 , 5 ] and surface-enhanced fluorescence [ 6 , 7 ]. Many efforts have been made to strengthen the local electric field via local surface plasmonic resonance.…”