Molecular dynamics studies of defect formation during heteroepitaxial growth of InGaN alloys on (0001) GaN surfaces

Abstract

We investigate the formation of extended defects during molecular-dynamics (MD) simulations of GaN and InGaN growth on (0001) and ([Formula: see text]) wurtzite-GaN surfaces. The simulated growths are conducted on an atypically large scale by sequentially injecting nearly a million individual vapor-phase atoms towards a fixed GaN surface; we apply time-and-position-dependent boundary constraints that vary the ensemble treatments of the vapor-phase, the near-surface solid-phase, and the bulk-like regions of the growing layer. The simulations employ newly optimized Stillinger-Weber In-Ga-N-system potentials, wherein multiple binary and ternary structures are included in the underlying density-functional-theory training sets, allowing improved treatment of In-Ga-related atomic interactions. To examine the effect of growth conditions, we study a matrix of >30 different MD-growth simulations for a range of In Ga N-alloy compositions (0 ≤ ≤ 0.4) and homologous growth temperatures [0.50 ≤ () ≤ 0.90], where () is the simulated melting point. Growths conducted on polar (0001) GaN substrates exhibit the formation of various extended defects including stacking faults/polymorphism, associated domain boundaries, surface roughness, dislocations, and voids. In contrast, selected growths conducted on semi-polar ([Formula: see text]) GaN, where the wurtzite-phase stacking sequence is revealed at the surface, exhibit the formation of far fewer stacking faults. We discuss variations in the defect formation with the MD growth conditions, and we compare the resulting simulated films to existing experimental observations in InGaN/GaN. While the palette of defects observed by MD closely resembles those observed in the past experiments, further work is needed to achieve truly predictive large-scale simulations of InGaN/GaN crystal growth using MD methodologies.

Dependence of defect structure on In concentration in InGaN epilayers grown on AlN/Si(111) substrate

“…Furthermore, there are several types of defects such as V-type defects, trench defects and sub-interfacial extended type defects could be appeared due to higher indium content and biaxial compressive strain in the material. But recent studies suggest that V types of defects are mostly kinetically driven, and it cannot be related with higher indium content and with biaxial compressive strain 15,[41][42][43] . On the other hand, it has been suggested that trench types of defects and subinterfacial extended types of defects can be related with higher indium content and as well as with biaxial compressive strain 15,41,42,44 .…”

Effect of Substrate Surface on Deposition of AlGaN: A Molecular Dynamics Simulation

“…It can accurately characterize the elastic, structural and dynamical properties of AlN and GaN, and can well describe the interatomic interaction between Al-Ga. Similar SW potentials have already been successfully applied to investigate InGaN film grown on GaN surface [20,21]. The parameters of Al-Ga-N SW potential are shown in Table 1.…”

“…(0001) Al-terminated surface substantially improves the surface roughness and crystal quality of deposited AlGaN film. Similarly, J. Gruber et al chose (0001) Ga-terminated GaN template for the growth of InGaN [20]. Ponce et al [40] examined smooth MOCVD films grown on sapphire with a low-temperature GaN buffer layer and reported them to be (0001) Ga-polar.…”

“…Recently, MD simulation has been extensively employed to systematically investigate the growth of III-V binary [18,19] and ternary compounds [20,21]. The growth of GaN on polar surfaces [18] and AlN on non-polar surfaces [19] were investigated; additionally, the growth of ternary InGaN film on polar [20] and non-polar [21] GaN surfaces was also discussed. The formation of defects on these planes was explored.…”

Horizons of modern molecular dynamics simulation in digitalized solid freeform fabrication with advanced materials

“…They provide an effective means to guide experiments to reduce these defects. and [112 ̅ 0] directions respectively [58,59] where the initial substrate, wurtzite, zinc-blende, and defective (i.e., undefinable) regions are shown in black, orange, blue, and white colours respectively. Almost defect-free structures can be grown in the [112 ̅ 0] growth direction (except for the surface which is coloured white), but significant defects (including alteration of wurtzite and zinc-blende regions) exist in the [0001] growth direction.…”