Structural, electronic and vibrational properties of InN under high pressure

Abstract

The structural, electronic and vibrational properties of InN under pressures up to 20 GPa have been investigated using the pseudo-potential plane wave method (PP-PW). The generalized-gradient approximation (GGA) in the frame of density functional theory (DFT) approach has been adopted. It is found that the transition from wurtzite (B4) to rocksalt (B1) phase occurs at a pressure of approximately 12.7 GPa. In addition, a change from a direct to an indirect band gap is observed. The mechanism of these changes is discussed. The phonon frequencies and densities of states (DOS) are derived using the linear response approach and density functional perturbation theory (DFPT). The properties of phonons are described by the harmonic approximation method. Our results show that phonons play an important role in the mechanism of phase transition and in the instability of B4 (wurtzite) just before the pressure of transition. At zero pressure our data agree well with recently reported experimental results.

Adsorption and Sensing Behaviors of Pd-Doped InN Monolayer upon CO and NO Molecules: A First-Principles Study

“…A 4 × 4 × 1 supercell of the InN monolayer was established, which contains 16 In atoms and 16 N atoms, with a vacuum region of 15 Å to prevent the interaction between adjacent units. The lattice constant of the InN monolayer calculated in this work was 3.62 Å, consistent with the previous work (3.63 Å [30]).…”

Structural and elastic stabilities of InN in both B4 and B1 phases under high pressure using density-functional perturbation theory

“…Theoretical studies based on total energy calculations clearly predicted the high pressure phase of InN is the rocksalt structure [8][9][10]. This was confirmed experimentally [3,11].…”

“…These constants are important in solid because they are closely related to various fundamental solid-state phenomena such as interatomic bonding, equations of state, and phonon spectra. According to our recent work [8], the phase transition pressure from the B4 to the B1 occurs at 12.7 GPa. For this reason, we have calculated the elastic parameters for B4 and B1 in the pressure range from 0 to 12.5 GPa and from 13 (after phase transition) to 20 GPa, respectively.…”

“…This low-pressure phase undergoes a structural transition to rocksalt phase at 12.1 GPa, as the pressure is increased [8].…”

Effects of NH3 Flow Rate on the Growth Mechanism and Optical Properties of InN Crystallites Fabricated by Chemical Vapor Deposition

“…As compared with the InN nanowires, the intensity of the emission band of the microcrystallites is slightly strengthened, while the maximum of the emission band exhibits a significant blue-shifting from 665 to 570 nm. In recent years, reports about the optical band gap of InN have provoked fierce debate, for they showed different values from 0.6 to 2.2 eV. ,,,, Currently, theoretical calculations and experimental results indicate that the intrinsic band gap of InN is ∼0.65 eV. − The PL properties of InN materials affected by their shape and size, as well as the synthetic process and parameters, have been widely reported. − The quantum confinement effect, oxygen impurities, strain effect, the defects including N antisite (N In ), In antisite (In N ), N vacancy (V N ), In vacancy (V In ), and a complex defect (N In +In N ), or the Moss–Burstein shift induced by high electron concentrations of the InN nanostructures have been proposed as possible reasons for an increased band gap of InN. ,,,,− Recent reports showed that the major reason for the larger band gap of InN is the influence of oxygen inclusion. − Davydov et al showed that an InN sample containing ∼20% of oxygen has a band gap in the region of 1.8–2.1 eV . And Yoshimoto et al reported that, with the values of oxygen molar fractions in a series of polycrystalline InN layers changed from 1% to 6%, the associated band gap increased from 1.55 to 2.27 eV .…”