Enhancing nitrogen solubility in GaAs and InAs by surface kinetics: Anab initiostudy

Abstract

Nitrogen solubility at GaAs and InAs ͑001͒ surfaces has been studied employing density-functional theory calculations. The effect of the surface reconstruction and the reconstruction-induced surface strain on N solubility was analyzed in detail, considering the various surface layers and sites. The stability phase diagrams for the considered systems were constructed, and based on them an estimate of the N concentration has been deduced for the thermodynamically accessible and relevant range of chemical potentials in the various surface layers and at a typical growth temperature of 500°C. Our results show that the solubility of N at the surface is unexpectedly rich and a complex function of the surface reconstructions. We discuss the possible N incorporation mechanisms and the conditions that allow for an enhanced solubility which can be in GaAs up to five orders of magnitude higher than the equilibrium bulk solubility. In addition, we find that the solubility of N at the GaAs͑001͒ surface is one to four orders of magnitude higher than that at the InAs͑001͒ surface.

Theoretical modeling of growth processes, extended defects, and electronic properties of III‐nitride semiconductor nanostructures

“…Indeed, as demonstrated in Ref. 14 under these extreme N rich growth conditions N concentrations up to few percents can be easily achieved consistent with experimental observations 80, 81.…”

“…In addition, the determination of the kinetic barriers is essential to identify the incorporation mechanism that is operational and dominant for a given growth environment (fluxes, temperature). By employing a comprehensive set of ab initio calculations and combining them with surface thermodynamics 14 and adatom incorporation kinetics 84, we were able to accomplish a complete understanding of the factors that control the incorporation of N in dilute nitride alloys 14, 13. To discuss the ideas and possibilities offered by this approach we give in the following a brief review on the solubility phase diagrams of N at GaAs(001) surface and show how they can be applied to study the various incorporation mechanisms.…”

“…Moreover, the results obtained from the ab initio computed phase diagrams show that the highest N solubility can be achieved by subsurface incorporation: in this layer, concentrations of up to 12.5% can be easily achieved under moderate‐poor As and N rich conditions. A detailed analysis 14 showed that the origin of this behavior is the creation of local compressive strain due to the formation of surface dimers. Therefore, the magnitude of the strain enhancement strongly depends on the specific surface reconstruction.…”

“…In this progress, theoretical tools and calculations have been and still are an indispensable tool in the research of this materials system. Just to mention a few cases, they have been extensively used to study a wide range of properties and various systems such as defects 2 and alloys 3–5, the mechanism of acceptor activation 6, 7, identification of equilibrium surface structures 8–11, surfactant and self‐surfactant effects 12, as well as kinetic stabilization of thermodynamically not‐accessible structures 13, 14.…”

Effects of plasma species on the N incorporation of GaAsSbN grown by plasma-assisted gas-source molecular-beam epitaxy

“…Zhang and Wei [18] suggested that potential energy of N species can increase the solubility of N in the host lattice up to 8 orders of magnitude. Abu-Farsakh and Nargebauer [19] further suggested that substitutional N atom solubility can be enhanced by surface kinetics. Their calculation showed that the incorporation of adatom in the second anion layer needs the lowest formation energy and is responsible for the high N atom solubility.…”