First-principles study of structural phase transformation and dynamical stability of cubic AlN semiconductors

Abstract

Phase transformation and stability of cubic aluminium nitride (AlN) phases such as zinc-blende and rock-salt have been investigated using first-principles calculations based on density functional perturbation theory (DFPT) within quasi-harmonic approximation (QHA). The phonon dispersion relations of both the cubic phases have been calculated at various high-symmetry points of the Brillouin Zone. The pressure and volume dependence of phonon frequencies have been investigated. The application of pressure results in opposite trend of transverse acoustic (TA) phonon frequencies for rock-salt and zinc-blende AlN phases. The TA frequencies found to increase for the former one and decrease for the latter one with the increase in pressure. The dynamical instability results in a volume expansion of rock-salt AlN close to the equilibrium volume of zinc-blende AlN. Phase transformation of these cubic phases is further investigated by computing an equilibrium pressure-temperature phase diagram within QHA. The cubic rock-salt AlN is found to form at high pressures and temperatures than zinc-blende AlN. The temperature dependence of lattice constant and the corresponding volume thermal expansion coefficient of both the cubic phases have been investigated.

Empirical prediction of thermal properties, microhardness and sound velocity of cubic zinc-blende AlN

“…where a is expressed in Å and T m is expressed in K. Replacing in Eq. (8), the lattice parameter (4.38 Å) [6] obtained at room temperature, the value of T m of AlN compound with the zinc-blende structure has been calculated and found to be 2967.4 K. This value agrees very well with the theoretical values 3000 K and 3060 K reported by Yaddanapudi [18] and in our previous work [19], respectively. The deviation of T m between our value (2967.4 K) and the theoretical one (3000 K) reported by Yaddanapudi [18] is only about 1.1%.…”

“…(8), the lattice parameter (4.38 Å) [6] obtained at room temperature, the value of T m of AlN compound with the zinc-blende structure has been calculated and found to be 2967.4 K. This value agrees very well with the theoretical values 3000 K and 3060 K reported by Yaddanapudi [18] and in our previous work [19], respectively. The deviation of T m between our value (2967.4 K) and the theoretical one (3000 K) reported by Yaddanapudi [18] is only about 1.1%. Since both polytypes (zinc-blende and wurtzite) have the same tetrahedral bonding (negligible difference in their chemical bonding) [34], our value of T m agrees also well with the experimental values of 3025 K [35] and 3023 K [36] of the hexagonal w-AlN compound.…”

“…Using the first principles according to density function theory, Yang et al [16] have studied the structural, elastic, thermodynamic, electronic and optical properties of several predicted novel phases of AlN material. Although several physical properties of AlN semiconducting compound were established in some other works [17,18], only limited theoretical investigation [19] has been reported for its thermal conductivity.…”

Thermomechanical, electronic and thermodynamic properties of ZnS cubic polymorphs: anab initioinvestigation on the zinc-blende–rock-salt phase transition

“…Non-acoustic negative frequencies are physically related to the so-called phonon softening, a behaviour that can be associated to different phenomena, e.g. change in ferroelectricity in the mineral as explained and already reported by several authors (Han et al, 2018;Nakanishi et al, 1982;Novoselov et al, 2018;Yaddanapudi, 2018). In the rs-ZnS case, these soft modes are due to a phase transition from an ordered crystal structure (NaCl-like) to a disordered one (zincblende).…”

Synthesis of Cubic Aluminum Nitride (AlN) Coatings through Suspension Plasma Spray (SPS) Technology

“…In addition, AlN has become the key component of semiconductor equipment, which is appropriate in piezoelectric and electronic applications [3]. Some of these amazing properties of AlN are summarized in Table 1, as high thermal conductivity [4], low thermal expansion coefficient [5], and a large band gap, which is a major factor that determines a solid's electrical conductivity [6], and this makes AlN an electrical insulator. Other characteristics include AlN's chemical and physical stability at fairly high temperature regions, high hardness [7], and high resistance to molten metals, wear and corrosion [5].…”