Atomistic origin of compositional pulling effect in wurtzite (B, Al, In)xGa1−xN: A first-principles study

Abstract

Some fluctuations in composition are commonly observed in epitaxial-grown III-V multinary alloys. These fluctuations are attributed to compositional pulling effects, and an insight into their atomistic origin is necessary to improve current epitaxial growth techniques. In addition, the crystallinity of III-V multinary alloys varies widely depending on the constituent atoms. Using first-principles calculations, we then investigated different geometric configurations of gallium nitride (GaN)-based ternary alloy, X 0.125 Ga 0.875 N where X is the minority atom which is boron (B), aluminum (Al), or indium (In). The minority atoms are presented as two atoms in the simulation cell, and the energetics of five geometric configurations are analyzed to estimate the most stable configuration. For the B 0.125 Ga 0.875 N alloy, the most stable configuration is the one where the minority atoms occupy gallium (Ga) sites in a collinear orientation along the c-axis. On the contrary, the configurations along the in-plane direction result in a higher energy state. In 0.125 Ga 0.875 N and Al 0.125 Ga 0.875 N also show the same trend with a small relative energy difference. These preferential sites of minority atoms are consistent with composition pulling effects in wurtzite nitride phases. Moreover, the degree of crystallinity for wurtzite nitride alloys can be well described by the order of calculated relative energy.

Thermodynamic Origin of High Efficiency in Long-Wavelength InGaN-Based LEDs on Si Substrates

“…That is, the composition of the film is close to GaN near the InGaN/GaN interface, and the In content increases with the growth of InGaN, which is called the composition-pulling effect. This phenomenon has been intensively reported in experimental studies and is demonstrated to directly affect the quality of InGaN films. − Several pseudosubstrate techniques are proposed to improve the quality of the InGaN film due to the composition-pulling effect Figure also shows that the formation energies of In Ga in all GaN layers are a monotonically decreasing function of strain from −5% (compressive) to 5% (tensile).…”

Formation energy crossings in Ga2O3-Al2O3 quasibinary system: ordered structures and phase transitions in (Al x Ga1−x )2O3

“…In addition we can also see that due to this stacking configuration, the Al and Ga atoms allow ordered alignments along the c-direction similar to the case of AlGaN in previous works. 42,43) The relatively higher formation energy of segregated Al 2 O 3 -Ga 2 O 3 layers can be associated to the strain between the Al 2 O 3 -Ga 2 O 3, brought about by the lattice mismatch of the pure phases. This strain can be lowered by having more distributed Al atoms as shown by the structure of the lowest energy configuration.…”

Metastable atomic-ordered configurations for Al1/2Ga1/2N predicted by Monte-Carlo method based on first-principles calculations

“…In our FPCs [28], density functional theory (DFT)-based total energy calculations were implemented [42]. Vienna ab initio Simulation Package was used to perform the total energy calculations [43,44] using projector augmented wave formalism and a plane wave basis set, with a cutoff energy of 700 eV [45,46].…”

“…The metastability of AlGaN is associated with the atomic ordering as observed by x-ray diffraction (XRD) and selected area electron beam diffraction (SAED) [15][16][17][18][19][20][21][22][23][24][25]. On the other hand, theoretical investigations have predicted the ordered configurations of AlGaN [12,[26][27][28].…”