SPLTRAK Abstract Submission
Cathodoluminescence characterization of GaAsSbN‑based materials for 1 eV multi-junction solar cell
Alicia Gonzalo1, Elisa García-Tabarés1, Lazar Stanojević2, J. M. Ulloa2, Juan Jiménez3, Beatriz Galiana1
1Departamento de Física, Universidad Carlos III de Madrid, Leganés, Madrid, Spain
/2Institute for Systems based on Optoelectronics and Microtechnology (ISOM), Universidad Politécnica de Madrid, Madrid, Spain
/3GdS-Optronlab Group, Dpto. Física de la Materia Condensada, Universidad de Valladolid, Valladolid, Spain

In the field of multi-junction solar cells (MJSCs), a good candidate for the 1 eV bandgap subcell is the GaAsSbN dilute nitride. GaAsSb/GaAsN superlattices (SLs) with type-II band alignment and few nanometer period thicknesses have been demonstrated to have better material homogeneity and subsequently improved solar cell performance than the GaAsSbN bulk counterpart.
Different GaAs(Sb)(N)-based structures have already been structurally and optically characterized by several techniques (e.g. TEM, XRD, PL), but the less common cathodoluminescence (CL) has the advantage of providing spatial resolution of the luminescence and therefore can be used to obtain, through optical measurements, insight into crystal quality at different points of the material.
In this work, a set of preliminary CL measurements has been performed over 1 eV bandgap samples: a GaAsSbN bulk and two type-II SLs with 6 and 3 nm-period thicknesses, to further investigate the crystal quality and the carrier diffusion properties of the material. Different energy beams have been employed to collect CL spectra at different positions along the epitaxial direction.
The first CL results agree with the conclusions reached through other techniques but also provide supplementary information, pointing towards the existence of small variations of composition along the growth direction in the GaAsSb/GaAsSbN SL structures. Therefore, the CL technique has been tested as a powerful tool with great potential for the characterization of dilute nitride SL structures.