Growth modes and chemical-phase separation in GaP1−xNx layers grown by chemical beam epitaxy on GaP/Si(001)

• Published in: Journal of applied physics Vol. 134; no. 17
• Main Authors: Ben Saddik, K., Fernández-Garrido, S., Volkov, R., Grandal, J., Borgardt, N., García, B. J.
• Format: Journal Article
• Language: English
• Published: 07.11.2023
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0173748

We investigated the chemical beam epitaxy of GaP 1 − xN x grown on nominally ( 001 )-oriented Si substrates, as desired for the lattice-matched integration of optoelectronic devices with the standard Si technology. The growth mode and the chemical, morphological, and structural properties of samples prepared using different growth temperatures and N precursor fluxes were analyzed by several techniques. Our results show that, up to x ≈ 0.04, it is possible to synthesize smooth and chemically homogeneous GaP 1 − xN x layers with a high structural quality. As the flux of the N precursor is increased at a given temperature to enhance N incorporation, the quality of the layers degrades upon exceeding a temperature-dependent threshold; above this threshold, the growing layer experiences a growth mode transition from 2D to 3D after reaching a critical thickness of a few nm. Following that transition, the morphology and the chemical composition become modulated along the [ 110 ] direction with a period of several tens of nm. The surface morphology is then characterized by the formation of { 113 }-faceted wires, while the N concentration is enhanced at the troughs formed in between adjacent ( 113 ) and ( 1 ¯ 1 ¯ 3 ). On the basis of this study, we conclude on the feasibility of fabricating homogeneous thick GaP 1 − xN x layers lattice matched to Si ( x = 0.021) or even with N content up to x = 0.04. The possibility of exceeding a N mole fraction of 0.04 without inducing coupled morphological–compositional modulations has also been demonstrated when the layer thickness is kept below the critical value for the 2D–3D growth mode transition.