%0 Journal Article 
%A Fernández de los Reyes, Daniel
%A Braza Blanco, María Verónica
%A Gonzalo, A.
%A Utrilla, A.D.
%A Ulloa, J.M.
%A Ben Fernández, Teresa
%A González Robledo, David
%T Modelling of the Sb and N distribution in type II GaAsSb/GaAsN superlattices for solar cell applications
%D 2018
%@ 01694332
%U http://hdl.handle.net/10498/30848
%X GaAsSbN dilute nitrides are potential candidates for integration in high-performance multi-junction solar cells due to the bandgap tunability in the 1.0–1.15 eV range and the possibility to match the lattice constant to the GaAs substrates. Recently, the use of GaAsSb/GaAsN superlattices (SLs) has been shown as an effective way to enhance photovoltaic efficiency as compared to the quaternary counterparts. Here we apply a combination of HR-XRD and cross-sectional (S)TEM techniques together with theoretical calculations to analyse the compositional distribution in GaAsSb/GaAsN SLs with different periodicity. The measurements of compositional profiles indicate that Sb is strongly segregated into the GaAsN layers while N remains confined where it is deposited. We demonstrate that the Sb profiles run as a shark-fin waveform that can be precisely described with a one-dimensional model where segregation of the supplied Sb is promoted by a three-layer fluid exchange mechanism. Moreover, the role played by the periodicity in the effectiveness of the Sb incorporation adds a new level of complexity. The modelling of Sb segregation in the GaAsSb/GaAsN SLs system could be used to carry out more precise pseudopotential calculations on the band structure in order to understand and predict their electrical and optical behaviour.
%K III–V semiconductors
%K Phase separation and segregation in semiconductors
%K Transmission electron microscopy (TEM)
%~ Universidad de Cádiz