Growth of aluminium nitride whiskers by sublimation-recrystallization method

Abstract

Aluminium nitride (AlN) with various morphologies was fabricated through a sublimation-recrystallization method. The influences of type of reactor and temperature gradient were explored, as well as the orientations and growth mechanism of the obtained AlN whiskers. In the early stage of preparation, a vapour-liquid-solid (VLS) mechanism dominated, producing AlN pillars, whiskers and noncrystalline fibres. In the later stage, as the catalyst liquid was removed by volatilization, the pillars and noncrystalline fibres stopped growing, but the growth of AlN whiskers continued through a vapour-solid (VS) mechanism. By Laue method and rotating-crystal method of x-ray diffraction, together with electron diffraction, most of the AlN whiskers were discovered to grow on planes $\left\{ {2\bar 1\bar 10} \right\},\left\{ {0001} \right\}$, or $\left\{ {10\bar 1|} \right\}$, where l = 0, 1, 2, 3, along crystal axes $\left\{ {2\bar 1\bar 10} \right\},\left\{ {0001} \right\}$, or $\left[ {10\bar 1w} \right]$, where w = 0, 1, 2, 3. Oblique grown whiskers also appeared, with a growth direction at an angle of about 54° to the growth plane, $\left\langle {10\bar 12} \right\rangle$.