Christopher Pashartis1 Oleg Rubel1

1, McMaster University, Hamilton, Ontario, Canada

The recent progress in formation of two-dimensional (2D) GaN by a migration-enhanced encapsulated technique [1] opens up new possibilities for group III-V 2D semiconductors with a band gap within the visible energy spectrum. The drawback of the planar monolayer GaN is its indirect band gap. Using first-principles calculations we explored alloying of 2D-GaN to achieve an optically active material with a tuneable band gap [2]. The effect of isoelectronic III-V substitutional elements on the band gaps, band offsets, and spatial electron localization is studied using a set of first-principle assays [3,4]. In addition to optoelectronic properties, the formability of alloys is evaluated using impurity formation energies. A dilute highly-mismatched solid solution 2D-GaN:P features an efficient band gap reduction in combination with a moderate energy penalty associated with incorporation of phosphorous in 2D-GaN. The energy penalty is substantially lower than in the case of the bulk GaN. The group-V alloying elements also introduce significant disorder and localization at the valence band edge that facilitates direct band gap optical transitions thus implying the feasibility of using III-V alloys of 2D-GaN in light-emitting devices.

[1] Z. Y. Al Balushi, K. Wang, R. K. Ghosh, R. A. Vilá, S. M. Eichfeld, J. D. Caldwell, X. Qin, Y.-C. Lin, P. A. DeSario, G. Stone, S. Subramanian, D. F. Paul, R. M. Wallace, S. Datta, J. M. Redwing, and J. A. Robinson, Nat. Mater. 15, 1166 (2016).
[2] C. Pashartis and O. Rubel, Phys. Rev. B 96, 155209 (2017).
[3] C. Pashartis and O. Rubel, Phys. Rev. Appl. 7, 64011 (2017).
[4] O. Rubel, A. Bokhanchuk, S. J. Ahmed, and E. Assmann, Phys. Rev. B 90, 115202 (2014).