Composition dependent growth dynamics in molecular beam epitaxy of GaInNAs solar cells

• Published in: Solar energy materials and solar cells 2014-05, Vol.124, p.150-158
• Main Authors: Aho, Arto, Polojärvi, Ville, Korpijärvi, Ville-Markus, Salmi, Joel, Tukiainen, Antti, Laukkanen, Pekka, Guina, Mircea
• Format: Article
• Language: English
• Subjects: Applied sciences; Concentrated photovoltaics; Current density; Dilute nitrides; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Exact sciences and technology; GaInNAs; Gallium arsenide; Gallium arsenides; Illumination; Molecular beam epitaxy; Multi-junction solar cells; Natural energy; Photoelectric conversion; Photovoltaic cells; Photovoltaic conversion; Plasma-assisted molecular beam epitaxy; Reconstruction; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2014.01.044

We have investigated the role of the nitrogen content, the growth parameters, and the annealing processes involved in molecular beam epitaxy of GaInNAs solar cells lattice-matched to GaAs. The nitrogen composition was varied between 1% and 5%. The influence of the growth temperature was assessed by performing photoluminescence, atomic force microscopy, X-ray diffraction, reflection high-energy electron diffraction, quantum efficiency and light-biased current–voltage measurements. The growth temperature ensuring the best cell parameters was found to be 440°C. At this temperature we were able to incorporate up to 4% of nitrogen and achieve a good material quality. Further increase of the N composition to 5% led to phase separation. For the lattice matched samples grown within the optimal temperature range, we have identified a clear (1×3) surface reconstruction. Using the optimized growth we have demonstrated a GaInNAs p-i-n solar cell structure containing 4% nitrogen, that exhibited a short-circuit current density as high as 33.8mA/cm2 in respect to effective area illuminated. These measurements have been performed under real sun AM1.5 (~1000W/m2) illumination. •Optimization of growth parameters for GaInNAs high efficiency solar cells.•High quality GaInNAs hetersotructures with different N content.•Generation of 33.8mA/cm2 from a GaInNAs solar cell (AM1.5).