Structural, electronic, and optical properties of the pressure‐driven novel polymorphs of gallium nitride : first‐principles investigations

Abstract

Summary Exploring new polymorphs of groups III to V compounds of evolved physical properties has recently received substantial interest from researchers. Accordingly, we explored new pressure‐driven polymorphs of gallium nitride (GaN) and investigated their physical properties using density functional theory (DFT)‐based full‐potential (FP) linearized‐augmented‐plus‐local‐orbital (L[APW + lo]) approach. Our analysis shows the transition of ground‐state wurtzite (wz) structure to beryllium oxide (β‐BeO)‐type structure at a tensile stress of ~−6.82 GPa and to silicon carbide (SiC)‐type structure by applying moderate compressive stress of magnitude 0.27 GPa. Similarly, the transition of wz‐GaN to nickle arsenide (NiAs) and titanium arsenide (TiAs)‐type structures has been realized at 43.78 and 45.72 GPa, respectively. These new polymorphs of GaN exhibited comparable cohesive energies with wz‐structure and the phonon dispersions free of imaginary frequencies, which indicate them as stable as the ground‐state wz‐phase. Investigations of the electronic structures show the wz‐, β‐BeO‐, and SiC‐phases of GaN as semiconductors of direct bandgap of energy 3.10, 3.15, and 2.97 eV, whereas the NiAs‐ and TiAs‐ phases of GaN exhibited indirect bandgap of energy 2.59 and 2.82 eV. All the GaN polymorphs demonstrated transparent behavior for the incident light photon of energy less than 13 eV. They exhibited optical absorption as high as 3.02 × 106 cm−1, 2.23 × 106 cm−1, 2.62 × 106 cm−1, 2.67 × 106 cm−1, and 2.67 × 106 cm−1 in the case of wz‐, β‐BeO‐, NiAs‐, SiC‐, and TiAs‐structured GaN, respectively. These interesting features of the novel polymorphs of GaN indicate them promising for electronic and optoelectronic applications.

First-Principles Investigations of the Physical Properties of Experimentally Feasible Novel Aluminum Nitride Polytypes

“…Over the past few decades, semiconductor materials have attracted substantial attention due to their remarkable physical properties, making them adaptable to many modern technological applications. − Of this large family, group III nitrides, particularly AlN, are characterized by a high melting point, high thermal conductivity, good dielectric strength, high degree of hardness, and direct wide band gap. These characteristics make AlN a suitable material for microelectronic substrate applications, short-wavelength light-emitting diodes, laser diodes, and optical detectors, as well as for high-temperature, high-power, and high-frequency devices. − Consequently, extensive research has been conducted to characterize, as precisely as possible, the essential optical and electronic properties of AlN, which are of primary importance, as well as its mechanical and structural response. − In contrast to the zincblende (ZB), wurtzite (WZ), and rock salt (RS) phases, no comprehensive experimental or theoretical investigation has been conducted on the polytypism of AlN.…”