The effect of the first GaN monolayer on the nitridation damage of molecular beam epitaxy grown GaN on GaAs(001)

Abstract

The initial molecular beam epitaxy growth of GaN on GaAs(001) was studied by real-time monitoring of the (3×3) surface reconstruction and its transition to an unreconstructed (1×1). Various growth conditions were established by variation of the V/III ratio, i.e., the Ga flux. We characterized the effect of the first two strained GaN monolayers: a N-terminated GaN (3×3) monolayer and a second unreconstructed (1×1) monolayer. A series of samples were grown under N-rich, Ga-rich, and near-stoichiometric growth conditions. The resulting morphology of the interface region was analyzed by high-resolution scanning electron microscopy, Auger-electron spectroscopy, and double crystal x-ray diffractometry. The N-rich and Ga-rich conditions resulted in extensive defect formation due to the nitridation damage of the GaAs substrate. The extent of this was found to be determined by the properties of the first GaN monolayer. The surface roughness under optimum growth conditions could be as low as ∼20 nm, defined by nanocrystalline grains, showing no observable nitridation damage.

New issue of GaN nanoparticles solar cell

“…The phase transformation observed at higher temperatures may be due to thermodynamic stabilization. The mechanisms responsible for the formation of the metastable nature of zinc-blende GaN phase at higher temperature is proposed, in which the impact of the ionic chemical reaction species impinging on the surface of growing nanoparticles plays a key role in phase transition the of GaN[11,37].The latice parameters of a =3.18 A o and c = 5.166A° for hexagonal phase are consistent with the standard values. The crystal grain size (D p ) of the GaN nanoparticles was calculated from the XRD peaks using Scherrer's formula (4)[31].…”

“…On the other hand, low growth temperature led to sufficient accumulation of Ga and atomic stacking faults in the wurtzite which has effect on the surface reconstruction of h-GaN [37,38].…”

As4 overpressure effects on the phase purity of cubic GaN layers grown on GaAs substrates by RF-MBE

“…In this last process was found that the content of c-GaN increases, by increasing the growth temperature at 700 • C, with a flux of arsenic at 2.4 × 10 −7 Torr [14]. The analysis by reflection high-energy electron diffraction (RHEED) for this layer showed, an initial (3 × 3) reconstruction during the growth of the first GaN monolayer [15]. However, is of great importance an understanding of the relaxation process of c-GaN during the nucleating layer, due to the impact on the final crystal quality.…”

Nitrogen–arsenic exchange processes and investigation of the nitrided GaAs surfaces in MOVPE

“…1(b)) in MBE. This reconstruction was monitored during GaN growth [12] and nitridation of GaAs [11] by supplying a GaAs ð2 Â 4Þ reconstruction with purified N 2 . Jung et al demonstrated with auger electron spectroscopy (AES) that the Ga/N ratio decreases strongly after tempering the sample.…”